| 1. |
- Abujrais, Sandy, et al.
(author)
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Analysis of tryptophan metabolites and related compounds in human and murine tissue : development and validation of a quantitative and semi-quantitative method using high resolution mass spectrometry
- 2024
-
In: Analytical Methods. - : Royal Society of Chemistry. - 1759-9660 .- 1759-9679. ; 16:7, s. 1074-1082
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Journal article (peer-reviewed)abstract
- This study explores the metabolic differences between human and murine plasma in addition to differences between murine subcutaneous and visceral white adipose tissue. A quantitative and semi-quantitative targeted method was developed and validated for this purpose. The quantitative method includes tryptophan and its metabolites in addition to tyrosine, phenylalanine, taurine, B vitamins, neopterin, cystathionine and hypoxanthine. While the semi-quantitative method includes; 3-indoleacetic acid, 5-hydroxyindoleacetic acid, acetylcholine, asymmetric dimethylarginine, citrulline and methionine. Sample preparation was based on protein precipitation, while quantification was conducted using ultrahigh-performance liquid chromatography coupled to a quadrupole Orbitrap tandem mass spectrometer with electrospray ionization in the parallel reaction monitoring (PRM) mode. The low limit of quantification for all metabolites ranged from 1 to 200 ng mL-1. Matrix effects and recoveries for stable isotope labelled internal standards were evaluated, with most having a coefficient of variation (CV) of less than 15%. Results showed that a majority of the analytes passed both the intra- and interday precision and accuracy criteria. The comparative analysis of human and murine plasma metabolites reveals species-specific variations within the tryptophan metabolic pathway. Notably, murine plasma generally exhibits elevated concentrations of most compounds in this pathway, with the exceptions of kynurenine and quinolinic acid. Moreover, the investigation uncovers noteworthy metabolic disparities between murine visceral and subcutaneous white adipose tissues, with the subcutaneous tissue demonstrating significantly higher concentrations of tryptophan, phenylalanine, tyrosine, and serotonin. The findings also show that even a semi-quantitative method can provide comparable results to quantitative methods from other studies and be effective for assessing metabolites in a complex sample. Overall, this study provides a robust platform to compare human and murine metabolism, providing a valuable insight to future investigations. A validated HRMS method for measuring tryptophan metabolites and related compounds has been developed, with simple sample preparation, successfully applied in human and murine plasma, as well as murine white adipose tissue.
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| 2. |
- Amin, Sidra, et al.
(author)
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A sensitive enzyme-free lactic acid sensor based on NiO nanoparticles for practical applications
- 2019
-
In: Analytical Methods. - : Royal Society of Chemistry. - 1759-9660 .- 1759-9679. ; 11, s. 3578-3583
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Journal article (peer-reviewed)abstract
- A facile and efficient electrochemical sensing platform has been successfully exploited for the first time for the determination of lactic acid using a nickel oxide (NiO) nanoparticle-modified glassy carbon electrode (GCE). Nickel oxide nanoparticles were prepared by a chemical growth method using different quantities of arginine as a soft template. The structural and morphological properties of NiO nanoparticles were characterized by Raman spectroscopy, scanning electron microscopy (SEM) and X-ray diffraction (XRD). Cyclic voltammetry (CV) was used to study the electrochemical properties of various samples. The modified electrode is highly sensitive and presents a linear response over a wide range (0.005–5 mM) of lactic acid concentrations in 0.1 M NaOH. The detection limit for the sensor was found to be 5.7 μM, and it exhibits good stability. Furthermore, the sensor shows excellent selectivity in the presence of common interfering species. The lactic acid sensor showed good viability for lactic acid analysis in real samples (milk, yogurt and red wine) and demonstrated significant advancement in sensor technology for practical applications.
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| 3. |
- Amini, Ahmad, et al.
(author)
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A protocol for the quality assessment of illegally distributed human growth hormones with respect to identity, purity, endotoxin level and microorganism content
- 2015
-
In: Analytical Methods. - 1759-9660 .- 1759-9679. ; 7:20, s. 8857-8864
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Journal article (peer-reviewed)abstract
- Different methods based on MALDI-TOF-MS and double injection capillary zone electrophoresis (DICZE) were used for the identification and purity determination of somatropin in illegally distributed products. During the past few years, more than 200 products suspected to contain somatropin have been analysed. Some of the samples were also subjected to control microorganisms and endotoxins. The identification of somatropin was carried out by peptide mapping using trypsin as the proteolytic enzyme. A double chain peptide cross-linked via a disulfide bond was used as the signature peptide. Capillary electrophoresis in double injection mode was applied to both identification and purity determination of the samples. The identification was based on the comparison between the observed migration time of the reference standard and the calculated migration time of the analyte, being present in the second injection plug. The DICZE provides electrophoretic fingerprints of intact somatropin and the related proteins which facilitate the identification. In addition, some of these samples revealed the presence of microorganisms as well as a high level of endotoxins. Taken together, the doubtful quality of the analysed samples and the microbiological findings represent a serious threat for the consumers and public health.
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| 4. |
- Aminlashgari, Nina, et al.
(author)
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Nanocomposites as novel surfaces for laser desorption ionization mass spectrometry
- 2011
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In: Analytical Methods. - : Royal Society of Chemistry (RSC). - 1759-9660 .- 1759-9679. ; 3:1, s. 192-197
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Journal article (peer-reviewed)abstract
- The possibility to utilize nanocomposite films as easy-to-handle surfaces for surface assisted laser desorption ionization-mass spectrometry (SALDI-MS) of small molecules, such as pharmaceutical compounds, was evaluated. The signal-to-noise values of acebutolol, propranolol and carbamazepine obtained on the nanocomposite surfaces were higher than the values obtained on plain PLA surface showing that the nanoparticles participate in the ionization/desorption process even when they are immobilized in the polymer matrix. The advantages of nanocomposite films compared to the free nanoparticles used in earlier studies are the ease of handling and reduction of instrument contamination since the particles are immobilized into the polymer matrix. Eight inorganic nanoparticles, titanium dioxide, silicon dioxide, magnesium oxide, hydroxyapatite, montmorillonite nanoclay, halloysite nanoclay, silicon nitride and graphitized carbon black at different concentrations were solution casted to films with polylactide (PLA). There were large differences in signal intensities depending on the type of drug, type of nanoparticle and the concentration of nanoparticles. Polylactide with 10% titanium oxide or 10% silicon nitride functioned best as SALDI-MS surfaces. The limit of detection (LOD) for the study was ranging from 1.7 ppm up to 56.3 ppm and the signal to noise relative standard deviations for the surface containing 10% silicon nitride was approximately 20-30%. Scanning electron microscopy demonstrated in most cases a good distribution of the nanoparticles in the polymer matrix and contact angle measurements showed increasing hydrophobicity when the nanoparticle concentration was increased, which could influence the desorption and ionization. Overall, the results show that nanocomposite films have potential as surfaces for SALDI-MS analysis of small molecules.
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| 5. |
- Antonio Lopez-Lopez, Jose, et al.
(author)
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Simple hollow fiber liquid membrane based pre-concentration of silver for atomic absorption spectrometry
- 2014
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In: Analytical Methods. - : Royal Society of Chemistry (RSC). - 1759-9660. ; 6:5, s. 1462-1467
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Journal article (peer-reviewed)abstract
- Silver pollution has gained attention in the last few years because silver is being massively used as a bactericide in self-care, medical and textile products. Difficulties of Ag determination are associated with the very low concentrations in which it is normally found (ng L-1) and the nature of the sample matrix. Standard methods such as liquid-liquid extraction (LLE) are regularly used. Alternatively, liquid phase micro-extraction (LPME) appears to be an environmentally friendly tool for sample treatment that offers higher pre-concentration factors. This allows the determination of ultra-trace levels of silver using standard instrumental techniques such as atomic absorption spectrometry. In this work, a hollow fiber LPME is proposed. Silver pre-concentration has been conducted using tri-isobutylphosphine sulphide (TIBPS) as a carrier from the sample to an acceptor solution through a solvent placed in the fiber pores. Accurel-PP 50/280 fibers with an internal volume of 20 mu L were used for 50 mL samples. After optimization, 0.1 M KNO3 in the sample, 0.1 M TIBPS in dihexyl ether as the organic phase and 1 M Na2S2O3 in the acceptor solution were established. The system offers enrichment factors of 1053 times, a limit of detection of 1.16 ng L-1. This method improves the limit of detection of the most recent liquid micro-extraction methods for silver pre-concentration coupled with GFAAS, being in this case comparable to ICP-MS detection based techniques.
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| 6. |
- Beal, Alexandra, et al.
(author)
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A new analytical method for lead determination in atmospheric particulate matter by a combination of ultrasound-assisted extraction and supramolecular solvent preconcentration
- 2018
-
In: Analytical Methods. - : Royal Society of Chemistry (RSC). - 1759-9660 .- 1759-9679. ; 10:30, s. 3745-3753
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Journal article (peer-reviewed)abstract
- Air pollution by lead, even in small concentrations, can cause serious health effects. In the atmosphere this element can generally be found in particulate matter (PM), and in general in small concentrations. This work proposes the development of an analytical method for lead determination in inhaled PM based on ultrasound-assisted extraction with subsequent supramolecular solvent based dispersive liquid-liquid microextraction (SM-DLLME), using reverse micelles of dodecanoic acid as an extractor dispersed in a continuous phase of tetrahydrofuran (THF)/water. The rich phase was then analyzed by thermospray flame furnace atomic absorption spectrometry (TS-FF-AAS) coupled on-line to a flow injection analysis (FIA). An analytical curve in the range of 15.0-200.0 μg L-1 (R2 = 0.999), an enrichment factor of 18.1 times and the limits of detection (LOD) and quantification (LOQ) equal to 3.7 and 11.3 μg L-1, respectively, were obtained. The accuracy of the method was successfully attested by comparing with EDX analysis through the paired t-test at a confidence level of 95%. The amount of lead determined in the samples of PM collected in different environments varied from 19.3 to 94.8 ng m-3.
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| 7. |
- Bergman, Nina, et al.
(author)
-
Quantitative determination of the Ru(bpy)(3)(2+) cation in photochemical reactions by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry
- 2014
-
In: Analytical Methods. - : Royal Society of Chemistry (RSC). - 1759-9660 .- 1759-9679. ; 6:21, s. 8513-8518
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Journal article (peer-reviewed)abstract
- The coordination compound of Ru(II) with three 2,2'-bipyridine ligands possesses a potent photosensitization capacity for electron- and energy-transfer processes. In combination with salts of peroxydisulfate acid as sacrificial electron acceptors, Ru(bpy)(3)(2+) is widely used for photocatalytic oxidative transformations in organic synthesis and water splitting. The drawback of this system is that bipyridine degrades under the resulting strongly oxidative conditions, the concentration of Ru(bpy)(3)(2+) diminishes, and the photocatalytic reaction eventually stops. A commonly employed assay for the determination of Ru(bpy)(3)(2+), UV-Vis spectroscopy, has low selectivity and does not distinguish between the intact complex and its decayed forms. Here, we report a matrix assisted laser desorption/ionisation mass spectrometric method for the quantitative analysis of Ru(bpy)(3)(2+) in photochemical reaction mixtures. The developed method was successfully used for the determination of intact Ru(bpy)(3)(2+) during the course of the water photooxidation reaction. The significant difference between the results of MALDI MS and UV-Vis analyses was observed.
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| 8. |
- Boström, Marja L., et al.
(author)
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A specific, highly enriching and "green" method for hollow fiber liquid phase microextraction of ionizable pharmaceuticals from fish tissue
- 2014
-
In: Analytical Methods. - : Royal Society of Chemistry (RSC). - 1759-9660. ; 6:15, s. 6031-6037
-
Journal article (peer-reviewed)abstract
- Ionizable pharmaceuticals are a class of emerging contaminants that pose a challenge to analytical chemistry due to their low environmental concentrations. To measure such low concentrations in organism tissue, e.g. fish muscle, specific extraction techniques minimizing co-extraction and interference alongside providing high enrichment of the compounds are needed. In this study we present a technique using hollow fiber liquid phase microextraction which is selective and highly enriching due to a pH gradient across a selective membrane, trapping ions in the extract. Microextraction minimizes the use of organic solvents, thereby making the technique "green". We used high volume pharmaceuticals for method development, specifically, the weak acids ketoprofen, naproxen, diclofenac and ibuprofen, and the weak bases fluoxetine and sertraline. Lyophilized tissue extraction gave higher enrichment than fresh tissue extraction and concentration enrichment factors ranged from 1900 to 3000 times. Method detection limits with the analysis instruments used in this study were for ketoprofen, 0.23 ng g(-1) fish tissue; naproxen, 0.32 ng g(-1) fish tissue; diclofenac, 0.12 ng g(-1) fish tissue; ibuprofen, 0.34 ng g-1 fish tissue; fluoxetine, 13 ng g-1. fish tissue and sertraline, 23 ng g(-1) fish tissue. All analytes were successfully detected in tissue from fish exposed live via spiked water. The resulting extraction parameters shown in this study suggest the developed technique to be a useful work up method for extensive environmental data collection as well as for toxicokinetic studies.
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| 9. |
- Chen, Changer Long, et al.
(author)
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Determination of fragrance ingredients in fish by ultrasound-assisted extraction followed by purge & trap
- 2017
-
In: Analytical Methods. - : Royal Society of Chemistry (RSC). - 1759-9660 .- 1759-9679. ; 9:15, s. 2237-2245
-
Journal article (peer-reviewed)abstract
- Fragrance materials are widely used in household and personal care products in applications that can lead to emissions into the aquatic environment. Assessing the potential of fragrance materials to bioaccumulate in fish in in vivo laboratory studies requires a reliable analytical method for determining the concentrations of chemical substances in fish tissue. Here, we present an analytical method for simultaneously measuring a group of model chemicals that are representative of chemicals found in fragrance materials in rainbow trout. This method involves ultrasound-assisted extraction (UAE) followed by enrichment of the fragrance ingredients using a purge & trap system. Nine fragrance ingredients including semi-volatile and volatile compounds were selected as model substances for method development. Homogenised whole rainbow trout subsamples were spiked with these nine model fragrance ingredients, hexachlorobenzene (HCB) and 2,2',5,5'-tetrachlorobiphenyl (PCB52). The targeted chemicals were extracted from the fish tissue using acetonitrile in an ultrasonic bath; after solvent exchange to hexane, they were extracted into the gas phase by heating the samples and purging with nitrogen and trapped on a solid-phase extraction (SPE) cartridge. Finally, these chemicals were eluted with hexane from the SPE column and analysed using gas chromatography-mass spectrometry (GC-MS). The proposed method has been evaluated for blanks, spiked recoveries and precision, which are all acceptable. We believe that the method presented here is generally applicable for analysis of acid-sensitive volatile and semi-volatile organic chemicals in fish and provides the basis to conduct in vivo bioaccumulation studies of fragrance materials.
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| 10. |
- Comina, German, et al.
(author)
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A 3D printed device for quantitative enzymatic detection using cell phones
- 2016
-
In: Analytical Methods. - : Royal Society of Chemistry. - 1759-9660 .- 1759-9679. ; 8:32, s. 6135-6142
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Journal article (peer-reviewed)abstract
- A disposable device for quantitative enzymatic detection capable of coupling illumination and image readouts from cell phones is demonstrated. The device integrates a calibration range for glutamate detection, utilizes the phone screen as a light source, and provides the necessary actuation for autonomous operation. Custom made optics required to couple to the cell phone camera is accomplished using affordable stereolithography (SLA) 3D printers. The described method does not involve polishing, requires only two steps from design to implementation, and can be locally applied to 3D printed lab-on-a-chip (LOC) prototypes, using the same materials. Optical finishing and dimensional variability within 2% were achieved, supporting entirely arbitrary geometries for elements larger than 400 mm in radius. Representative fabrication times and costs were 20 min and $0.50 USD per prototype.
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| 11. |
- Decker, Daniel, et al.
(author)
-
A luminescence-based assay of UDP-sugar producing pyrophosphorylases
- 2014
-
In: Analytical Methods. - 1759-9660 .- 1759-9679. ; 6:1, s. 57-61
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Journal article (peer-reviewed)abstract
- A coupled luminescence assay was applied to monitor pyrophosphate (PPi) production by either purified barley UDP-glucose pyrophosphorylase (UGPase) or purified Leishmania UDP-sugar pyrophosphorylase (USPase). In the assay, the PPi produced by the pyrophosphorylases was converted to ATP by ATP-sulfurylase, and the ATP produced was linked to luminescent light formation through the action of firefly luciferase. The assay allowed for a quantitative measurement of UGPase and USPase activities, down to a pmol per min level. The activities were linear with time and proportional to the amount of the enzyme added, and were neither affected by Pi nor by DTT. For UGPase, K-m values with UTP and Glc-1-P were 0.14 and 0.26 mM, respectively, whereas for USPase the respective K-m values with UTP, Glc-1-P and Gal-1-P were 0.4, 2.9 and 3.9 mM. Possible applications of the luminescence-based assay for not only UDP-sugar producing pyrophosphorylases, but also other types of pyrophosphorylases are discussed.
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| 12. |
- Do, Lan, et al.
(author)
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Modular pressurized liquid extraction for simultaneous extraction, clean-up and fractionation of PCDD/Fs in soil, sediment and sludge samples
- 2013
-
In: Analytical Methods. - : RSC Publishing. - 1759-9660 .- 1759-9679. ; :5, s. 1231-1237
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Journal article (peer-reviewed)abstract
- Modular pressurized liquid extraction (M-PLE) procedures were developed for simultaneous extraction, clean-up and fractionation of polychlorinated dioxins and furans (PCDD/Fs) in soil, sediment and sludge samples. The procedures utilize two coupled extraction cells: an upstream cell filled with the sample and layers of silica and acid- and base-modified silica, and a downstream cell filled with activated carbon. The silica layers were added to remove polar or hydrolysable matrix components, and the carbon to perform planarity-based fractionation. Two solvent systems (dichloromethane–heptane, DCM–Hp and diethyl ether–heptane, DEE–Hp) and two activated carbon loads (1% and 3% carbon on Celite) were evaluated using certified reference materials (CRM-529 and WMS-01) and materials from previous inter-calibration studies. Using any of the four procedures, data statistically equivalent to the certified or reference values were obtained. The M-PLE procedure using DCM–Hp and 1% carbon sometimes extracted the reference materials more efficiently than the reference methods, while the DEE–Hp procedure extracted them equally efficient, offering an alternative with less environmental impact. The methods with 1% carbon on Celite produced sufficiently pure extracts for sample loads up to one gram, but for greater sample loads the higher carbon load (3% carbon on Celite) was required to avoid breakthrough of target analytes. The new streamlined procedures are fast, cost-efficient, involve relatively low environmental impact (in the case of DEE–Hp) and are well suited for high-throughput analysis of solid samples, e.g. in connection with environmental monitoring campaigns and major soil remediation efforts.
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| 13. |
- Durgaryan, Andranik, et al.
(author)
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Identification of human chorionic gonadotropin hormone in illegally distributed products by MALDI-TOF mass spectrometry and double-injection capillary zone electrophoresis
- 2016
-
In: Analytical Methods. - : Royal Society of Chemistry (RSC). - 1759-9660 .- 1759-9679. ; 8:21, s. 4188-4196
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Journal article (peer-reviewed)abstract
- This paper describes two complementary methods, based on peptide-mass fingerprinting (PMF) using MALDI-TOF mass spectrometry and double injection capillary zone electrophoresis for identification of human chorionic gonadotropin (hCG). The identification was performed by determining the amino acid composition and comparing measured mass spectra with those predicted in silico. Capillary zone electrophoresis in double injection mode (DICZE) was used to confirm the identity of the protein. In DICZE, the identification was performed by analyzing illegal samples together with the corresponding reference standard during a double injection capillary zone electrophoretic run. The identification was based on the closeness of agreement between the calculated migration time (t(mig(c))) and the observed migration time (tmig) of the reference standard. Furthermore, the DICZE method provides the possibility to compare the electrophoretic separation patterns of the native reference standard and the target analyte. The inner surface of the capillary was dynamically coated with putrescine, present in the BGE at 8.2 mM, to improve the separation. The CZE analyses revealed that the protein consisted of at least ten glycosylated isoforms.
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| 14. |
- Ghaani, Masoud, et al.
(author)
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A bionanocomposite- modified glassy carbon electrode for the determination of 4,4 0-methylene diphenyl diamine
- 2018
-
In: Analytical Methods. - : Royal Society of Chemistry. - 1759-9660 .- 1759-9679. ; 10:34
-
Journal article (peer-reviewed)abstract
- A nanosensor based on a glassy carbon electrode modified with the biopolymer chitosan, multi-wall carbon nanotubes, and gold nanoparticles (MWCNTs-CS-AuNPs/GCE) was developed for the determination of 4,4-diaminodiphenyl diamine (MDA). Cyclic voltammetry (CV) was used to investigate the electrochemical behavior of the sensor in the presence of MDA. MDA displayed a well-expressed oxidation peak at 0.54 V (versus Ag/AgCl) in Britton-Robinson (B-R) universal buffer solution (pH = 10). The transfer coefficient, , and the overall number of electrons (n) involved in the catalytic oxidation of MDA at the MWCNTs-CS-AuNPs/GCE surface were also determined by CV. The reactivity of spiked MDA was strongly dependent on the pH of the supporting electrolyte, with the pH dependence of the MDA oxidation quantified as 27.576 mV pH(-1). Through chronoamperometry, the diffusion coefficient (D) of MDA was calculated to be 9.49 x 10(-5) cm(2) s(-1). The limit of detection of MDA was estimated to be approximate to 20 nM through amperometry experiments, while three linear ranges were found for MDA, i.e., 0.49-10.14 M, 10.14-94.9 M, and 94.9-261.18 M. Real sample tests enabled us to emphasize the potential of this nanocomposite-modified electrode as a new analytical tool for the determination of MDA.
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| 15. |
- Giesecke, Marianne, et al.
(author)
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The protonation state and binding mode in a metal coordination complex from the charge measured in solution by electrophoretic NMR
- 2013
-
In: Analytical Methods. - : Royal Society of Chemistry (RSC). - 1759-9660 .- 1759-9679. ; 5:7, s. 1648-1651
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Journal article (peer-reviewed)abstract
- We measured with high accuracy the effective charge of a uranium (VI)-AMP complex by electrophoretic NMR (eNMR). Using the same method, the degree of counterion association is also assessed which leads to a quantitative determination of the nominal charge which then provides the degree of ligand deprotonation in the complex. This demonstrates a new application of eNMR for resolving structural details of supramolecular complexes.
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| 16. |
- Groeneveld, Marloes M., et al.
(author)
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The influence of pH on dissolved organic matter fluorescence in inland waters
- 2022
-
In: Analytical Methods. - : Royal Society of Chemistry. - 1759-9660 .- 1759-9679. ; 14:13, s. 1351-1360
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Journal article (peer-reviewed)abstract
- Fluorescence is an easily available analytical technique used to assess the optical characteristics of dissolved organic matter (DOM). Despite widespread use, there has been some confusion about how robust fluorescence spectroscopy is to differences in solution pH. Here we assess fluorescence characteristics of three natural water samples and one commercially available standard (Nordic Reservoir) by modifying the pH across a range from 3.5 to 9.0 at 0.5 pH increments. We used two statistical approaches to assess if fluorescence intensity shifted significantly across this pH range. We identified that humic-like and protein-like fluorescence was largely stable within the pH range of 5.5 to 7.5, which represents 80% of Swedish lakes and streams. Likewise, we found that the three commonly used fluorescence indices were robust across the full pH range tested with the exception of the humification index, which had a narrower range of stability. The commerical humic substance sample was highly unstable with changes to pH in the regions of protein-like fluorescence being particularly sensitive. One of our conclusions is that differences in fluorescence intensity in the pH range of 5.5 to 7.5, typical for most inland waters, are generally minor. We recommend adjusting the pH when samples fall outside this region and to be especially careful in interpreting results from commercial humic substances.
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| 17. |
- Guo, Zhiming, et al.
(author)
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Determination of perchlorate in tea using SERS with a superhydrophobically treated cysteine modified silver film/polydimethylsiloxane substrate
- 2021
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In: Analytical Methods. - : Royal Society of Chemistry. - 1759-9660 .- 1759-9679. ; 13:13, s. 1625-1634
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Journal article (peer-reviewed)abstract
- Perchlorate is a new type of persistent pollutant, which interferes with the synthesis and secretion of thyroxine and affects human health. The EU's limit for perchlorate in tea is 750 mu g kg(-1). The surface-enhanced Raman scattering (SERS) technique has the characteristics of a simple pretreatment method, rapid detection, high sensitivity, high specificity and great stability in the detection of perchlorate. This study proposed a novel superhydrophobic SERS substrate, which can be used to detect perchlorate in tea. Firstly, a chemical deposition method was used to deposit a silver film on the surface of a thin layer of polydimethylsiloxane. After drying, the substrate was immersed in 1H,1H,2H,2H-perfluorodecyltriethoxysilane aqueous solution for 15 hours to make the surface of the substrate superhydrophobic. Then cysteine molecules were deposited on the surface of the silver film/polydimethylsiloxane by incubation. The superhydrophobic surface has a unique enrichment effect on the highly diluted solution, and perchlorate has a strong affinity for the amino group of cysteine. We collected the Raman spectra of 9 gradient concentrations (1-100 mu mol L-1) of perchlorate-spiked tea samples on the hydrophobic substrate, and a linear model of the relationship between the SERS spectral intensity and the concentrations of perchlorate in tea was established. This method reached a good limit of detection of 0.0067 mu mol L-1 (0.82 mu g kg(-1)) in tea, which showed that the developed sensor has high sensitivity and could be used as a fast and simple technique for quantitative detection of perchlorate based on SERS technology.
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| 18. |
- Harris, L. F., et al.
(author)
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A fully integrated microfluidic device for point of care monitoring of antithrombotics
- 2016
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In: Analytical Methods. - : ROYAL SOC CHEMISTRY. - 1759-9660 .- 1759-9679. ; 8:35, s. 6500-6505
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Journal article (peer-reviewed)abstract
- The simplicity and efficiency of point of care diagnostics have revolutionised patient care. Current methods for measuring hypercoagulability often require trained technicians, large blood volumes, and result in long turnaround times. Standard testing for hypercoagulable disorders is performed in the central laboratory using automated coagulation analysers. However the trend is moving towards the development and implementation of point of care testing, as a result of the ever increasing number of patients on antithrombotic therapy. We present a novel microfluidic device and assay for monitoring the effect of two anticoagulants, unfractionated heparin (UFH) and low molecular weight heparin (LMWH). The assay is based on the anti-Xa assay principle but uses fluorescence detection. Our device is a disposable laminate microfluidic strip, fabricated from the cyclic polyolefin (COP), Zeonor (R), which is extremely suitable for application to fluorescent device platforms. We present data on the execution of the anti-Xa assay in this microfluidic format, demonstrating that the assay can be used to measure both UFH and LMWH in human plasma samples from 0 to 1 U mL(-1), with a rapid result obtained within 30-60 seconds.
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| 19. |
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| 20. |
- Hellwig, Johannes, et al.
(author)
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Measuring elasticity of wet cellulose beads with an AFM colloidal probe using a linearized DMT model
- 2017
-
In: Analytical Methods. - : Royal Society of Chemistry. - 1759-9660 .- 1759-9679. ; 9:27, s. 4019-4022
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Journal article (peer-reviewed)abstract
- The mechanical properties of wet cellulose are investigated using an atomic force microscope AFM and calculated using a linearized DMT model. Measurements were performed using a model system of gel beads made of cellulose with different charge densities, which show a high impact on the mechanical properties of the cellulose in wet state.
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| 21. |
- Hellwig, Johannes, et al.
(author)
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Measuring elasticity of wet cellulose fibres with AFM using indentation and a linearized Hertz model
- 2018
-
In: Analytical Methods. - : Royal Society of Chemistry. - 1759-9660 .- 1759-9679. ; 10:31
-
Journal article (peer-reviewed)abstract
- The mechanical properties of different pulp fibres in liquid were measured using an atomic force microscope. Specifically a custom-made sample holder was used to indent the fibre surface, without causing any motion, and the Young's modulus was calculated from the indentation using a linearized Hertz model.
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| 22. |
- Hodek, Ondrej, et al.
(author)
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Mixed-mode chromatography-mass spectrometry enables targeted and untargeted screening of carboxylic acids in biological samples
- 2022
-
In: Analytical Methods. - : Royal Society of Chemistry (RSC). - 1759-9660 .- 1759-9679. ; 14, s. 1015-1022
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Journal article (peer-reviewed)abstract
- Carboxylic acids are crucial metabolites in the tricarboxylic acid (TCA) cycle and thus participate in central carbon metabolism (CCM). Research dependent on the analysis of metabolites involved in central carbon metabolism requires fast separation and sensitive detection of carboxylic acids using liquid chromatography-mass spectrometry (LC-MS). However, successful separation of all carboxylic acids from the TCA cycle by liquid chromatography remains a challenging task because of their high polarity and thus low retention on the conventional reversed-phase columns. In this study, we tested a reversed-phase/anion exchange mixed-mode stationary phase (Waters BEH C-18 AX) using liquid chromatography-tandem mass spectrometry (LC-MS/MS). We developed and optimized a method that enables a 10 minute separation of all carboxylic acids from the TCA cycle and lactic acid without prior derivatization or addition of ion-pair reagents in the mobile phase. The developed method was validated for quantification of 8 acids in murine brown preadipocytes, 5 acids in human plasma and 6 acids in Arabidopsis thaliana leaves with limits of quantification ranging from 0.1 mu M for malic acid to 10 mu M for isocitric acid. Moreover, the mixed-mode chromatography enabled untargeted screening of medium- to long-chain fatty acids in murine brown preadipocytes, Arabidopsis thaliana, and human plasma, where 23 fatty acids were identified by using liquid chromatography with high-resolution mass spectrometry (HRMS).
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| 23. |
- Holm, S. H., et al.
(author)
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Simplifying microfluidic separation devices towards field-detection of blood parasites
- 2016
-
In: Analytical Methods. - : Royal Society of Chemistry (RSC). - 1759-9660 .- 1759-9679. ; 8:16, s. 3291-3300
-
Journal article (peer-reviewed)abstract
- With our sights set on a simple and inexpensive diagnostics device based on extraction and enrichment of parasites from human blood, we present a device design that relies on a combination of multiple different deterministic lateral displacement arrays. Our end goal is a microfluidic device that will be easy to use in the rural, resource-deprived areas where simple-to-use medical tools are crucially needed for rapid and accurate diagnosis. Here, we exemplify this in the application of blood parasite enrichment from a sample of blood. With trypanosomes as a model system we show a combination of functionalities designed into a single device based on several deterministic lateral displacement arrays of different depths arranged in series. With only one inlet and no expensive or complicated pumping mechanisms to run separations we ensure the level of simplicity necessary for field use.
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| 24. |
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| 25. |
- Kumar, Keshav, et al.
(author)
-
Chromatographic analysis of peptidoglycan samples with the aid of a chemometric technique : introducing a novel analytical procedure to classify bacterial cell wall collection
- 2019
-
In: Analytical Methods. - : Royal Society of Chemistry (RSC). - 1759-9660 .- 1759-9679. ; 11:12, s. 1671-1679
-
Journal article (peer-reviewed)abstract
- The technical development of liquid chromatography has provided the necessary sensitivity to characterise peptidoglycan samples. However, the analysis of large numbers of complex chromatographic data sets without the aid of a proper chemometric technique is a laborious task, carrying a high risk of losing important biochemical information. The present work describes the development of a simple analytical procedure using self-organising map (SOM) analysis to analyse the large number of complex chromatographic data sets from bacterial peptidoglycan samples. SOM analysis essentially maps the samples to a hexagonal sheet based on their compositional similarity, and thus provides an approach to classify the bacterial cell wall collection in an unsupervised manner. The utility of the proposed approach was successfully validated by analysing peptidoglycan samples belonging to the Alphaproteobacterium class. The classification results achieved with SOM analysis were found to correlate well with their relative similarity in peptidoglycan compositions. In summary, the SOM analysis-based analytical procedure is shown to be useful towards automatising the analyses of chromatographic data sets of peptidoglycan samples from bacterial collections.
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| 26. |
- Kumar, Keshav
(author)
-
Discrete wavelet assisted correlation optimised warping of chromatograms : optimizing the computational time for correcting the drifts in peak positions
- 2017
-
In: Analytical Methods. - : Royal Society of Chemistry (RSC). - 1759-9660 .- 1759-9679. ; 9:13, s. 2049-2058
-
Journal article (peer-reviewed)abstract
- Correlation optimised warping (COW) has been the most favourite chromatographic peak alignment approach in recent years. After optimization of the two parameters, slack and segment length, COW works well in aligning the chromatograms. However, one of the serious disadvantages of COW is that it is computationally time consuming. Often several segment lengths and slack parameters need to be tested to find the optimum combination for achieving the alignment that makes the whole analysis take several hours. In the present work, it has been shown that with the application of wavelet analysis prior to alignment it is possible to provide the necessary computational economy to the COW algorithm.
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| 27. |
- Kumar, Keshav, et al.
(author)
-
Integrating network analysis with chromatography : introducing a novel chemometry-chromatography based analytical procedure to classify the bacterial cell wall collection
- 2018
-
In: Analytical Methods. - : Royal Society of Chemistry. - 1759-9660 .- 1759-9679. ; 10:10, s. 1172-1180
-
Journal article (peer-reviewed)abstract
- The present work integrates network analysis with chromatography and proposes a novel analytical procedure to classify the bacterial cell wall collection. The network analysis model can capture the heterogeneity present in the datasets and hence can provide unsupervised classification. The proposed approach is successfully applied for classifying the peptidoglycan samples of certain bacterial collections belonging to the class of Alphaproteobacteria. The obtained classification results are found to correlate well with their relative similarity in the peptidoglycan compositions. In summary, the proposed network analysis approach can be helpful in automatizing the bacterial cell wall analysis. The proposed approach can be useful to accelerate the research related to understanding the morphology of bacterial cell walls, host-pathogen interaction and development of effective antibiotics.
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| 28. |
- Larsson, Niklas, et al.
(author)
-
Continuous flow hollow fiber liquid-phase microextraction and monitoring of NSAID pharmaceuticals in a sewage treatment plant effluent
- 2009
-
In: Analytical Methods. - : Royal Society of Chemistry (RSC). - 1759-9660 .- 1759-9679. ; 1:1, s. 59-67
-
Journal article (peer-reviewed)abstract
- A method for simultaneous extraction and quantification Of four non-steroidal anti-inflammatory drugs (NSAIDs) based on continuous flow hollow fiber liquid-phase microextraction (CFHF-LPME) was developed. The effect of sample flow rate, acceptor flow rate, type of acceptor flow (continuous, semi-continuous or forward-backward), type of supported liquid membrane and sample volume was studied. The extraction of the final method was linear over an environmentally relevant concentration range and yielded high enrichment factors (720-940 times) in reagent water and (270-800 times) in sewage water for all analytes within 45 min. Repeatability was best (RSD 6-15%) during the first 30 min of extraction. The optimised method was used to monitor the occurrence and fate of the four NSAIDs in a Swedish sewage treatment plant (STP) effluent, which is discharged into a system of ponds before release into a river, during the period May-September 2008. All four analytes were detected at concentrations up to 0.92 mu g L-1 ketoprofen, 0.08 mu g L-1 naproxen, 0.43 mu g L-1 diclofenac and 0.25 mu g L-1 ibuprofen. A concentration drop during the summer was observed. For diclofenac and ketoprofen significant removal in the primary recipient pond system was observed. The presence of the studied pharmaceuticals in STP effluent together with concern about their environmental effects makes monitoring of their occurrence and knowledge of their environmental fate important. The proposed method provides a basis for automation of extraction towards on-site extraction using CFHF-LPME.
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| 29. |
- Li, Shuai, et al.
(author)
-
Response strategies and biological applications of organic fluorescent thermometry: cell- and mitochondrion-level detection
- 2024
-
In: Analytical Methods. - : ROYAL SOC CHEMISTRY. - 1759-9660 .- 1759-9679.
-
Research review (peer-reviewed)abstract
- Temperature homeostasis is critical for cells to perform their physiological functions. Among the diverse methods for temperature detection, fluorescent temperature probes stand out as a proven and effective tool, especially for monitoring temperature in cells and suborganelles, with a specific emphasis on mitochondria. The utilization of these probes provides a new opportunity to enhance our understanding of the mechanisms and interconnections underlying various physiological activities related to temperature homeostasis. However, the complexity and variability of cells and suborganelles necessitate fluorescent temperature probes with high resolution and sensitivity. To meet the demanding requirements for intracellular/subcellular temperature detection, several strategies have been developed, offering a range of options to address this challenge. This review examines four fundamental temperature-response strategies employed by small molecule and polymer probes, including intramolecular rotation, polarity sensitivity, Forster resonance energy transfer, and structural changes. The primary emphasis was placed on elucidating molecular design and biological applications specific to each type of probe. Furthermore, this review provides an insightful discussion on factors that may affect fluorescent thermometry, providing valuable perspectives for future development in the field. Finally, the review concludes by presenting cutting-edge response strategies and research insights for mitigating biases in temperature sensing. In this review, we primarily summarized four temperature-response strategies. Then, we further analyzed the chemical modifications and biological applications of the probes. Finally, we have provided a prospective on the future development of probes.
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| 30. |
- Makaraviciute, Asta, et al.
(author)
-
Antibody fragment immobilization on planar gold and gold nanoparticle modified quartz crystal microbalance with dissipation sensor surfaces for immunosensor applications
- 2014
-
In: Analytical Methods. - : Royal Society of Chemistry. - 1759-9660 .- 1759-9679. ; 6:7, s. 2134-2140
-
Journal article (peer-reviewed)abstract
- Immunosensors are bioaffinity sensors incorporating immune system molecules that are utilized for analyte recognition and signal transduction yielding a measurable signal upon analyte detection. A lot of effort has been made to optimize the immobilization matrix on the sensor surface since the outcome of the ligand immobilization procedure determines sensitivity, specificity and longevity of the developed immunosensor. In this work, antibodies against bovine leukemia virus antigen gp51 were chemically reduced to "half" antibody fragments that were later employed as recognition ligands. Antibody fragments at different concentrations were immobilized via thiolate bonds on planar gold and gold nanoparticle modified surfaces of a quartz crystal microbalance with dissipation sensor. Antibody fragment immobilization and interaction with antigen were investigated. Antibody fragment surface mass densities after the immobilization on planar gold and gold nanoparticle modified sensor surfaces were directly dependent on the initial antibody concentration. The highest analytical response was exhibited by antibody fragments immobilized at the smallest surface mass density on planar gold and gold nanoparticle modified surfaces. Bovine leukemia virus antigen gp51 interaction with antibody fragments was compared with non-specific gp51 interaction with bovine serum albumin on planar gold and gold nanoparticle modified surfaces by employing Delta D/Delta f plots.
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| 31. |
- Malinovskiy, Dmitry, et al.
(author)
-
Vanadium isotope ratio measurements in fruit-bodies of Amanita muscaria
- 2016
-
In: Analytical Methods. - : Royal Society of Chemistry (RSC). - 1759-9660 .- 1759-9679. ; 8:30, s. 5921-5929
-
Journal article (peer-reviewed)abstract
- A new method has been developed for precise vanadium isotope ratio measurements by multi-collector inductively coupled plasma mass spectrometry (MC-ICPMS) in Amanita muscaria - a widespread toxic and hallucinogenic mushroom which is also known for its ability to bio-accumulate vanadium. Prior to isotope ratio measurements vanadium was separated from the sample matrix by anion-exchange chromatography with a single run of a sample solution through the anion-exchange column sufficient for the purification of vanadium. V-51/V-50 isotope ratio measurements were carried out in the high resolution mode of MC-ICPMS which allowed the separation of V-50(+) and V-51(+) ions from polyatomic interfering species, including sulphur-based ions. Iron was employed as an admixed internal standard and was found effective in correcting for the drift of instrumental mass bias. An important feature of the method was the use of a regression model in data reduction. The Plackett-Burman factorial design was used for ruggedness testing and showed that normalisation to the Fe-56/Fe-54 isotope ratio of the internal standard significantly improved the repeatability of the results. The combined standard uncertainties of delta V-51 values determined for samples of the mushroom ranged from 0.28 parts per thousand to 0.42 parts per thousand. delta V-51 values for the samples collected in geographically different locations varied from -0.7 parts per thousand to 1.7 parts per thousand, suggesting V-51/V-50 isotope ratio measurements as a useful tool for identifying the origin of Amanita muscaria in tasks concerned with counteracting the abuse of hallucinogenic mushrooms and in studies on the biochemistry of vanadium.
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| 32. |
- Malinovsky, Dmitry N., et al.
(author)
-
Molybdenum isotope fractionation in plants measured by MC-ICPMS
- 2018
-
In: Analytical Methods. - : Royal Society of Chemistry. - 1759-9660 .- 1759-9679. ; 10:1, s. 131-137
-
Journal article (peer-reviewed)abstract
- A new method was developed for precise and accurate Mo isotope ratio measurements in plant materials by multi-collector inductively coupled plasma mass spectrometry (MC-ICPMS). It is based on the use of anion-exchange chromatography to isolate Mo from concomitant matrix elements in sample digests, a desolvating Apex-Q sample inlet system as a means of Mo signal enhancement and on-line normalisation to an admixed internal standard (Pd) to correct for instrumental mass bias. Mo isotope ratios were determined in sample solutions with Mo concentrations as low as 10 ng g-1. The developed method was successfully applied to the determination of natural variations in the isotopic composition of Mo in different anatomical parts of plants. We show for the first time that Mo isotope fractionation can occur during long-distance transport of Mo in plants. Our data also show that the magnitude of Mo isotope fractionation during translocation of Mo is different for different plant species. Mo isotope ratio data obtained by MC-ICPMS can therefore be used as a sensitive probe of processes controlling transport and distribution of molybdenum in plants.
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| 33. |
- Manaprasertsak, Auraya, et al.
(author)
-
Imaging the distribution of DMPBD and terpinen-4-ol inclusion complexes with 2-hydroxypropyl-beta-cyclodextrin by using TOF-SIMS
- 2021
-
In: Analytical Methods. - : Royal Society of Chemistry (RSC). - 1759-9679 .- 1759-9660. ; 13:1, s. 84-89
-
Journal article (peer-reviewed)abstract
- The distribution of terpinen-4-ol (TP4ol) and DMPBD inclusion complexes with 2-hydroxypropyl-beta-cyclodextrin (HPbCD) in human skin has been investigated using the TOF-SIMS technique. TP4ol and DMPBD have been found to be major components of Zingiber cassumunar Roxb. (Plai) oil extracted by steam distillation. The results mainly show accumulation of TP4ol and DMPBD inclusion complexes with HPbCD in the epidermis and dermis whereas these two compounds without cyclodextrin cannot penetrate into the epidermis. This approach can be expanded for investigation of anti-inflammatory action and relief of muscle pain.
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| 34. |
- Masala, Silvia, et al.
(author)
-
Pressurized liquid extraction as an alternative to the Soxhlet extraction procedure stated in the US EPA method TO-13A for the recovery of polycyclic aromatic hydrocarbons adsorbed on polyurethane foam plugs
- 2014
-
In: Analytical Methods. - : Royal Society of Chemistry (RSC). - 1759-9660 .- 1759-9679. ; 6:20, s. 8420-8425
-
Journal article (peer-reviewed)abstract
- The aim of the present study was to develop a pressurized liquid extraction (PLE) method as an alternative to the relatively time consuming Soxhlet extraction procedure described in the United States Environmental Protection Agency (US EPA) method TO-13A for the extraction of PAHs adsorbed onto polyurethane foam plugs (PUFs). For this purpose PUF air samples were collected and split into two parts: one part extracted using PLE and the other one using Soxhlet extraction. Comparable PAH concentrations were obtained upon analysis of the extracts showing that the PLE method developed in this work is a more convenient choice than the commonly used Soxhlet extraction technique proposed by US EPA for the determination of PAHs in air samples. In fact, the developed PLE method required shorter assay times (minutes versus hours), less solvent consumption and simpler operational methods. The exhaustiveness of the developed PLE method was evaluated using repeat static extraction cycles, demonstrating an extraction efficiency for the PAHs of greater than 99%. The PLE method was then applied to diesel exhaust and wood smoke PUF samples showing an extraction efficiency for the PAHs of greater than 93% and 96%, respectively. Furthermore, a PLE method for PUF cleaning was developed as well and employed as an alternative to Soxhlet extraction. The PLE methods developed for cleaning and extracting PUFs presented in this work are suitable to be used in mutagenicity studies using the Ames Salmonella assay as no mutagenicity was found in the PLE generated blanks
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| 35. |
- Mullin, Lauren, 1984-, et al.
(author)
-
Rapid separation of hexabromocyclododecane diastereomers using a novel method combining convergence chromatography and tandem mass spectrometry
- 2015
-
In: Analytical Methods. - : Royal Society of Chemistry. - 1759-9660 .- 1759-9679. ; 7:7, s. 2950-2958
-
Journal article (peer-reviewed)abstract
- Analysis of the brominated flame retardant hexabromocyclododecane (HBCDD) is characterized by the separation of its three predominant diastereomers. This analysis is typically performed using reversed phase liquid chromatography (RPLC) coupled with mass spectrometric (MS) detection with analysis times in the order of 10 minutes or greater. Here we describe a rapid method using supercritical CO2 and methanol to baseline separate the three most abundant HBCDD diastereomers within a three minute run time using a High Strength Silica (HSS) C18 1.8 mu m particle size column. A unique elution order of the alpha-, beta- and gamma-HBCDD diastereomers using supercritical CO2 was observed, and can be used as an orthogonal separation for further confidence in diastereomer identification when used in conjuction with RPLC. A tandem quadrupole mass spectrometer with negative mode electrospray ionization was used for detection, operating in multiple reaction monitoring (MRM) mode. Ionization was enhanced by the addition of a make-up flow, which was introduced to the post-column effluent. Method limit of detection (LOD) and limit of quantification (LOQ) for alpha-, beta- and gamma-HBCDD were based on peak-to-peak signal to noise ratios of greater than 3 or 10, respectively. The LOD for all HBCDD diastereomers as solvent standards was 100 fg on-column, and LOQs 500 fg on-column for alpha- and gamma-HBCDD and 250 fg on-column for beta-HBCDD. In order to test the efficiency of this method, small subsets of complex human serum and whale blubber extracts were analyzed using this method, resulting in positive detections in samples of alpha-HBCDD.
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| 36. |
- Murphy, Kathleen, 1972, et al.
(author)
-
Fluorescence spectroscopy and multi-way techniques. PARAFAC
- 2013
-
In: Analytical Methods. - : Royal Society of Chemistry (RSC). - 1759-9679 .- 1759-9660. ; 5:23, s. 6557-6566
-
Journal article (peer-reviewed)abstract
- PARAllel FACtor analysis (PARAFAC) is increasingly used to decompose fluorescence excitation emission matrices (EEMs) into their underlying chemical components. In the ideal case where fluorescence conforms to Beers Law, this process can lead to the mathematical identification and quantification of independently varying fluorophores. However, many practical and analytical hurdles stand between EEM datasets and their chemical interpretation. This article provides a tutorial in the practical application of PARAFAC to fluorescence datasets, demonstrated using a dissolved organic matter (DOM) fluorescence dataset. A new toolbox for MATLAB is presented to support improved visualisation and sensitivity analyses of PARAFAC models in fluorescence spectroscopy. © 2013 The Royal Society of Chemistry.
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| 37. |
- Murphy, Kathleen, 1972, et al.
(author)
-
OpenFluor- an online spectral library of auto-fluorescence by organic compounds in the environment
- 2014
-
In: Analytical Methods. - : Royal Society of Chemistry (RSC). - 1759-9679 .- 1759-9660. ; 6:3, s. 658-661
-
Journal article (peer-reviewed)abstract
- An online repository of published organic fluorescence spectra has been developed, which can be searched for quantitative matches with any set of unknown spectra. It fills a critical gap by increasing access to measured and modelled (PARAFAC) spectra, and linking across studies and systems to reveal "global" fluorescence trends.
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| 38. |
- Nasef, Hany, et al.
(author)
-
Labelless electrochemical melting curve analysis for rapid mutation detection
- 2010
-
In: Analytical Methods. - : Royal Society of Chemistry. - 1759-9660 .- 1759-9679. ; 2:10, s. 1461-1466
-
Journal article (peer-reviewed)abstract
- In the post-genome era there is an increasing demand for cost effective and rapid methods for thedetection of specific mutations and single nucleotide polymorphisms. Here we describe a method forthe rapid detection of mutations exploiting labelless electrochemical melting curve analysis, using thedetection of the cystic fibrosis associated DF508 mutant as a model. A 21-base long thiolated probe,complementary to the region of Exon 10 of the cystic fibrosis transmembrane regulatory gene where theDF508 mutation lies, was immobilised on a gold electrode and hybridised to a synthetic analogue ofsingle stranded PCR products for each of the mutant (85 bases) and wild type (82 bases) targets.Experimental conditions were optimised to exploit the guanine-specific interaction of the electroactiveindicator, methylene blue. Upon hybridisation of the immobilised probe to the target, the number ofguanine bases present in close proximity with the sensor surface increased from 3 to 14, resulting ina significant increase in signal. Ramping of the temperature caused denaturation of the on-surfaceimmobilised duplex and a concomitant reduction in signal. From the first derivative of the meltingcurves a clear differentiation between the mutant and wild-type target could be observed. The proposedapproach can be extended to array based melting curve analysis, allowing the simultaneous detection ofmultiple mutations and SNPs, and moreover the melting properties observed can also be used to designgenosensors for single target detection.
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| 39. |
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| 40. |
- Onoshima, Daisuke, et al.
(author)
-
A deep microfluidic absorbance detection cell replicated from a thickly stacked SU-8 dry film resist mold
- 2012
-
In: Analytical Methods. - : Royal Society of Chemistry (RSC). - 1759-9660 .- 1759-9679. ; 4, s. 4368-4372
-
Journal article (peer-reviewed)abstract
- Dry film resist SU-8 was used to make a thick mold for soft lithography of a poly(dimethylsiloxane) (PDMS) microfluidic chip with deep channels. The stacking of the SU-8 film enabled an ultra-thick (up to 500 μm) resist process on Si wafer. This process was fast and highly reproducible compared with the conventional liquid SU-8 process. The deep channel in the PDMS chip was utilized as a micro-flow cell for sensitive absorbance measurement. Sunset Yellow FCF dye was used to demonstrate absorption spectroscopy in the deep channel. Since the channel depth was proportional to the optical path length, which was proportional to the absorbance value, the PDMS chip achieved a detection limit (15.9 μM) comparable to U- or Z-shaped microfabricated absorbance detection cells in glass. Calibration curves for different solution concentrations were obtained with good R2 values (∼1). © 2012 The Royal Society of Chemistry.
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| 41. |
- Oppong Bekoe, Samuel, et al.
(author)
-
Determination of thirteen antibiotics in drug products : a new LC-MS/MS tool for screening drug product quality
- 2014
-
In: Analytical Methods. - 1759-9660 .- 1759-9679. ; 6, s. 5847-5855
-
Journal article (peer-reviewed)abstract
- Poor quality antibiotic medicines in circulation in Sub-Saharan Africa continue to be a burden. Pharmaceutical trade in substandard and counterfeit medicines is on the rise. The chemical quality of antibiotics dispensed in health facilities and recognised drug outlets in Ghana, when compromised, could be a major drawback to efforts made in fighting antibiotic resistance globally. To improve on antibiotic drug quality monitoring, a liquid chromatography-tandem mass spectrometry (LC-MS/MS) methodology, which is capable of quantifying thirteen antibiotics in drug products, was developed and validated in present work. The methodology was applied to various drug products including tablets, capsules, suspensions, syrups, intravenous and injection solutions as well as ear and eye droplets used as essential medicines in a Sub-Saharan country, Ghana.
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| 42. |
- Oppong Bekoe, Samuel, et al.
(author)
-
Determination of thirteen antibiotics in drug products : a new LC-MS/MS tool for screening drug product quality
- 2014
-
In: Analytical Methods. - : Royal Society of Chemistry. - 1759-9660 .- 1759-9679. ; 6, s. 5847-5855
-
Journal article (peer-reviewed)abstract
- Poor quality antibiotic medicines in circulation in Sub-Saharan Africa continue to be a burden. Pharmaceutical trade in substandard and counterfeit medicines is on the rise. The chemical quality of antibiotics dispensed in health facilities and recognised drug outlets in Ghana, when compromised, could be a major drawback to efforts made in fighting antibiotic resistance globally. To improve on antibiotic drug quality monitoring, a liquid chromatography-tandem mass spectrometry (LC-MS/MS) methodology, which is capable of quantifying thirteen antibiotics in drug products, was developed and validated in present work. The methodology was applied to various drug products including tablets, capsules, suspensions, syrups, intravenous and injection solutions as well as ear and eye droplets used as essential medicines in a Sub-Saharan country, Ghana.
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| 43. |
- Petra, Majer, et al.
(author)
-
Evaluation of procedures for assessing anti- and pro-oxidants in plant samples
- 2016
-
In: Analytical Methods. - Cambridge, United Kingdom : Royal Society of Chemistry. - 1759-9660 .- 1759-9679. ; 8:28, s. 5569-5580
-
Research review (peer-reviewed)abstract
- Plants as well as other aerobic organisms constantly produce reactive oxygen species (ROS). At regulatedlow concentrations ROS may serve as signal molecules, while in excessive amounts these may causeoxidative damage to biomolecules. Actual cellular concentrations are controlled by a network of variousantioxidants, and acclimation to stress conditions is achieved by a dynamic balance of ROS productionand neutralization. Accordingly, plant stress physiology studies generally include an array of methodstesting the occurrence of ROS as well as evaluating antioxidant capacities. The aim of the present workis to provide an overview of these methods, with special emphasis on avoiding errors that can possiblylead to either inaccurate data or misinterpretations of otherwise correct measurements.
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| 44. |
- Quaranta, Alessandro, et al.
(author)
-
Glycosylation profiling of selected proteins in cerebrospinal fluid from Alzheimer's disease and healthy subjects
- 2019
-
In: Analytical Methods. - : Royal Society of Chemistry (RSC). - 1759-9660 .- 1759-9679. ; 11:26, s. 3331-3340
-
Journal article (peer-reviewed)abstract
- Alteration of glycosylation has been observed in several diseases, such as cancer and neurodegenerative disorders. The study of changes in glycosylation could lead to a better understanding of mechanisms underlying these diseases and to the identification of new biomarkers. In this work the N-linked glycosylation of five target proteins in cerebrospinal fluid (CSF) from Alzheimer's disease (AD) patients and healthy controls have been analyzed for the first time. The investigated proteins, transferrin (TFN), alpha-1-antitrypsin (AAT), C1-inhibitor, immunoglobulin G (IgG), and alpha-1-acid glycoprotein (AGP), were selected based on the availability of VHH antibody fragments and their potential involvement in neurodegenerative and inflammation diseases. AD patients showed alterations in the glycosylation of low abundance proteins, such as C1-inhibitor and alpha-1-acid glycoprotein. These alterations would not have been detected if the glycosylation profile of the total CSF had been analyzed, due to the masking effect of the dominant profiles of high abundance glycoproteins, such as IgG. Information obtained from single proteins was not sufficient to correctly classify the two sample groups; however, by using an advanced multivariate technique a total non-error rate of 72 +/- 3% was obtained. In fact, the corresponding model was able to correctly classify 71 +/- 4% of the healthy subjects and 74 +/- 7% of the AD patients. Even if the results were not conclusive for AD, this approach could be extremely useful for diseases in which glycosylation changes are reported to be more extensive, such as several types of cancer and autoimmune diseases.
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| 45. |
- Razmi, Nasrin, et al.
(author)
-
Electrochemical genosensor based on gold nanostars for the detection of Escherichia coli O157:H7 DNA
- 2022
-
In: Analytical Methods. - : Royal Society of Chemistry. - 1759-9660 .- 1759-9679. ; 14:16, s. 1562-1570
-
Journal article (peer-reviewed)abstract
- Escherichia coli O157:H7 (E. coli O157:H7) is an enterohemorrhagic E. coli (EHEC), which has been issued as a major threat to public health worldwide due to fatal contamination of water and food. Thus, its rapid and accurate detection has tremendous importance in environmental monitoring and human health. In this regard, we report a simple and sensitive electrochemical DNA biosensor by targeting Z3276 as a genetic marker in river water. The surface of the designed gold electrode was functionalized with gold nanostars and an aminated specific sensing probe of E. coli O157:H7 to fabricate the genosensor. Cyclic voltammetry (CV) and square wave voltammetry (SWV) techniques were applied for electrochemical characterization and detection. The synthesized gold nanostars were characterized using different characterization techniques. The fabricated DNA-based sensor exhibited a high selective ability for one, two, and three-base mismatched sequences. Regeneration, stability, selectivity, and kinetics of the bioassay were investigated. Under optimal conditions, the fabricated genosensor exhibited a linear response range of 10(-5) to 10(-17) mu M in the standard sample and 7.3 to 1 x 10(-17) mu M in water samples with a low limit of quantification of 0.01 zM in water samples. The detection strategy based on silver plated gold nanostars and DNA hybridization improved the sensitivity and specificity of the assay for E. coli O157:H7 detection in real water samples without filtration. The detection assay has the advantages of high selectivity, sensitivity, low amounts of reagents, short analysis time, commercialization, and potential application for the determination of other pathogenic bacteria.
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| 46. |
- Retrato, Mark Dennis Chico, et al.
(author)
-
Simultaneous determination of 22 fatty acids in total parenteral nutrition (TPN) components by gas chromatography-mass spectrometry (GC-MS)
- 2023
-
In: Analytical Methods. - : Royal Society of Chemistry. - 1759-9660 .- 1759-9679. ; 15:20, s. 2480-2489
-
Journal article (peer-reviewed)abstract
- Evaluating total parenteral nutrition (TPN) products for quality assurance and quality control is crucial due to the chemical complexity of its components. With the advent of exploring different approaches for analysing TPN components using tandem mass spectrometry techniques, there is still a need for a robust and reproducible method for industrial routine analyses. This study allows simple, simultaneous determination of 22 fatty acids (FAs) commonly found in TPN components using gas chromatography-mass spectrometry (GC-MS). Five different transesterification techniques were applied for the FA standards and the sodium methoxide in methanol-dimethyl carbonate method was selected due to its good methylation efficiency. Fatty acid methyl esters (FAMEs) were separated in gas chromatography using an HP-5MS UI column with helium as the carrier gas. Mass spectrometry was used to fragment and quantify FAMEs using electron ionization (EI) and selected ion monitoring (SIM) mode. The analytical method was evaluated using the guidelines from the US Food and Drug Agency (FDA) and European Medicines Agency (EMA) in compliance with the International Council for Harmonization (ICH) document Q2(R2). Correlation coefficients (R-2) of the calibration curves for FAMEs were 0.99, except for C24:1 n-9 and C24:0, both R-2 = 0.98. The limits of detection (LOD) and quantification (LOQ) were found to be 1.69 mu g mL(-1) and 5.14 mu g mL(-1), respectively. The linear range was from 3.10-179.9 mu g mL(-1) for most FAMEs, except for C18:1 n-7 (3.96-224.9 mu g mL(-1)) and C18:1 n-9 (6.30-349.57 mu g mL(-1)). The intra-day and inter-day precision coefficients of variance (CV) of the method were less than 11.10% and 11.30%, respectively. Freeze-thaw cycles and ambient temperature measurements were performed for assessing sample stability. The validated method was applied to analyse major TPN components-fish and olive oils, and an unidentified lipid sample. The presented GC-MS method is simple and robust in the identification and quantification of 22 fatty acids simultaneously in the tested TPN components.
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| 47. |
- Riddell, Nicole, 1979-, et al.
(author)
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Comparative assessment of the chromatographic separation of 2,3,7,8-substituted polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans using supercritical fluid chromatography and high resolution gas chromatography
- 2015
-
In: Analytical Methods. - : Royal Society of Chemistry. - 1759-9660 .- 1759-9679. ; 7:21, s. 9245-9253
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Journal article (peer-reviewed)abstract
- The analysis of legacy environmental contaminants, such as polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs), using high resolution gas chromatography (HRGC) is well established and universally accepted. The use of an alternative separation technique, such as packed column supercritical fluid chromatography (pSFC), may be of interest as a fast, green, and cost effective method of analyzing environmental samples. The technique is amenable to a broad range of chemical compounds and could facilitate the simultaneous analysis of multiple compound classes as well as the inclusion of thermally labile compounds in a single targeted analysis. The recent re-emergence of this technology due to the introduction of more robust and efficient instrumentation may result in an increased acceptance of pSFC analytical techniques in this area. Herein, the first reported analytical separation of PCDDs and PCDFs by pSFC is described and its separation capabilities are compared with established HRGC protocols. Elution profiles of 2,3,7,8-substituted PCDDs and PCDFs were examined and the separation of PCDD/PCDF homologue groups was found to be comparable to those accomplished using HRGC. Similarly, the resolution of tetrachlorodibenzo-p-dioxin (TCDD) congeners, as required by current regulatory methods utilizing HRGC, was demonstrated and the separation of possible co-eluting PCDD/PCDF congeners was examined and compared to that achieved using popular HRGC capillary columns. The possibility of concurrent analysis of toxic polychlorinated biphenyls (PCBs) with PCDDs and PCDFs using the developed pSFC method was also investigated. The effective separation of these environmental contaminants obtained using pSFC and subsequent detection utilizing atmospheric pressure photoionization tandem mass spectrometry at environmentally relevant levels demonstrates the promise associated with this technique for the analysis of environmental extracts.
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| 48. |
- Ripszam, Matyas, et al.
(author)
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Elimination of interferences caused by simultaneous use of deuterated and carbon-13 standards in GC-MS analysis of polycyclic aromatic hydrocarbons (PAHs) in extracts from passive sampling devices
- 2013
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In: Analytical Methods. - : Royal Society of Chemistry (RSC). - 1759-9660 .- 1759-9679. ; 5:12, s. 2925-2928
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Journal article (peer-reviewed)abstract
- Two types of isotope-labelled reference compounds are typically used for the passive sampling of polycyclic aromatic hydrocarbons. One type is added before the exposure of the sampler and is called a performance reference compound (PRC). The other is the laboratory internal standard, which is spiked into the sample after extraction (dialysis) from the membrane and is used for quantification. Generally, PRCs are deuterium-labelled while internal standards are C-13-labelled. Interference originating from the internal standards occurs when the molecular ions of the PRCs gradually lose deuterium in the ion source to generate fragments that overlap with the molecular ions of the C-13-labelled internal standards. This can cause significant systematic errors in quantification. Gas chromatography-high resolution time-of-flight mass spectrometry (GC-HRTOF-MS) was used to investigate the degree of interference at varying virtual resolutions of the MS instrument, and it was shown that many of the spectral interferences can be avoided by using high MS resolutions (35 000 or better).
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| 49. |
- Salomonsson, Matilda Lampinen, et al.
(author)
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Development and in-house validation of a method for quantification of BMAA in mussels using dansyl chloride derivatization and ultra performance liquid chromatography tandem mass spectrometry
- 2013
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In: Analytical Methods. - : Royal Society of Chemistry (RSC). - 1759-9660 .- 1759-9679. ; 5:18, s. 4865-4874
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Journal article (peer-reviewed)abstract
- A new approach for the detection and quantification of beta-N-methylamino-L-alanine (BMAA) in mussels using chemical derivatization with dansyl chloride and ultra performance liquid chromatography-electrospray ionization-tandem mass spectrometry (UPLC-ESI-MS/MS) is presented. The method, using dansyl chloride as the reagent, is simple, robust and cost efficient. Comparing the fragmentation patterns for derivatized BMAA and its isomer L-2,4-diaminobutyric acid derivatized a selective fragment for the derivatized BMAA was formed m/z 585 > m/z 71. To ensure an actual detection of BMAA, the ion ratio of the daughter ions m/z 71 and m/z 277 was calculated and compared with the calculated mean ion ratio. The method development resulted in a simplified sample preparation excluding solid phase extraction and, instead, performing filtration and dilution of the samples before the derivatization. Validation was performed and the limit of quantification was determined to be 0.15 mu g g(-1) wet mussel homogenate (33 fmol per injection) and the limit of detection was estimated to be 16 ng g(-1) (4 fmol per injection). The intra-and inter-day precisions were within the accepted criteria and the recovery was about 83%. The stability of BMAA in the stock solution was at least 3 months and the stability of derivatized extracts in vials for the quantification was good for 27 days. This is the first quantification method for BMAA in mussels with extensive validation data published and the method was also applied on real mussel samples collected on the west coast of Sweden. The concentrations of BMAA in the mussel samples were determined to be between 0.27 and 1.6 mu g g(-1) wet mussel homogenates.
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| 50. |
- Smirnova, Adelina, et al.
(author)
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Enzyme-linked immunosorbent assay using thin-layered microfluidics with perfect capture of the target protein
- 2023
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In: Analytical Methods. - : Royal Society of Chemistry (RSC). - 1759-9660 .- 1759-9679. ; 15:5, s. 675-684
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Journal article (peer-reviewed)abstract
- We developed a process for enzyme-linked immunosorbent assay on a glass microchip via the use of a thin-layered microfluidic channel. This channel possesses a high aspect ratio (width/depth ∼200) and has an antibody layer immobilized directly on the channel surface. A depth of several microns and an excessive width and length (mm scale) of the channel provide a large-volume capacity (102 nL) and maximum capture efficiency of the analyte for a high level of detection sensitivity (102 pg mL−1). The developed reusable immunosensor has demonstrated high-performance characteristics by requiring less than 50 μL of sample and providing analysis in less than 25 min. This new method could impact the development of point-of-care devices for biomedical applications.
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