| 1. |
- Abuzooda, Thana, et al.
(författare)
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Graphite-based microextraction by packed sorbent for online extraction of beta-blockers from human plasma samples
- 2015
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Ingår i: Journal of chromatography. B. - : Elsevier BV. - 1570-0232 .- 1873-376X. ; 992, s. 86-90
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Tidskriftsartikel (refereegranskat)abstract
- In the present work a new graphitic material (Carbon-XCOS) was used as a sorbent for microextraction by packed sorbent (MEPS).The beta-blockers metoprolol and acebutolol in plasma samples were extracted and detected online using Carbon-MEPS syringe and liquid chromatography and tandem mass spectrometry (LC-MS/MS). Factors affecting the MEPS performance such as conditioning, washing and elution solutions were investigated. The validation of the bioanalytical method was performed using human plasma. The standard curve ranged from 10 to 2000 nM and the lower limit of quantification (LLOQ) was set to 10 nM. The method validation showed good accuracy and precision for the quality control (QC) samples at three concentration levels (30, 800 and 1600 nM). The accuracy values of the QC samples were in the range of 86-108% (n = 18). The precision values of intra- and inter-day for QC samples ranged from 4.4% to 14.4% (RSD) for the both studied analytes. The coefficient of determination (R-2) values were >= 0.999 (n = 3).
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| 2. |
- Ahmadi, Mazaher, et al.
(författare)
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Reduced graphene oxide as an efficient sorbent in microextraction by packed sorbent : Determination of local anesthetics in human plasma and saliva samples utilizing liquid chromatography-tandem mass spectrometry
- 2018
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Ingår i: Journal of chromatography. B. - : ELSEVIER SCIENCE BV. - 1570-0232 .- 1873-376X. ; 1095, s. 177-182
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Tidskriftsartikel (refereegranskat)abstract
- Herein, reduced graphene oxide (RGO) has been utilized as an efficient sorbent in microextraction by packed sorbent (MEPS). The combination of MEPS and liquid chromatography-tandem mass spectrometry has been used to develop a method for the extraction and determination of three local anesthetics (i.e. lidocaine, prilocaine, and ropivacaine) in human plasma and saliva samples. The results showed that the utilization of RGO in MEPS could minimize the matrix effect so that no interfering peaks at the retention times of the analytes or internal standard was observed. The high extraction efficiency of this method was approved by mean recoveries of 97.26-106.83% and 95.21-105.83% for the studied analytes in plasma and saliva samples, respectively. Intra- and inter-day accuracies and precisions for all analytes were in good accordance with the international regulations. The accuracy values (as percentage deviation from the nominal value) of the quality control samples were between - 2.1 to 13.9 for lidocaine, - 4.2 to 11.0 for prilocaine and between - 4.5 to - 2.4 for ropivacaine in plasma samples while the values were ranged from - 4.6 to 1.6 for lidocaine, from - 4.2 to 15.5 for prilocaine and from - 3.3 to - 2.3 for ropivacaine in human saliva samples. Lower and upper limit of quantification (LLOQ, ULOQ) were set at 5 and 2000 nmol L-1 for all of the studied drugs. The correlation coefficients values were >= 0.995. The limit of detection values were obtained 4 nmol L-1 for lidocaine and prilocaine, and 2 nmol L-1 for ropivacaine.
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| 3. |
- Asliyuce Coban, Sevgi, et al.
(författare)
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Synthesis and use of protein G imprinted cryogel as affinity matrix to purify protein G from cell lyaste.
- 2016
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Ingår i: Journal of Chromatography. B. - : Elsevier BV. - 1873-376X .- 1570-0232. ; 1021, s. 204-212
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Tidskriftsartikel (refereegranskat)abstract
- Monolithic macroporous cryogel imprinted with protein G was prepared using a functional co-monomer of N-methacryloyl-l-phenylalanine and 2-hydroxyethyl methacrylate. The chemical structure of the cryogel prepared was studied by FTIR-spectroscopy and its porosity was analysed using scanning electron microscopy. The cryogel was used to purify protein G from recombinant Escherichia coli cell lysate and the effect of pH, temperature, ionic strength, flow rate, etc on the adsorption of protein G to the monolithic column have been investigated. The selectivity of the imprinted cryogel was studied using protein A and myoglobin. It was possible to capture about 9mg of Protein G per g of the cryogel.
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| 4. |
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| 5. |
- Boström, Tove, et al.
(författare)
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Antibodies as means for selective mass spectrometry
- 2016
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Ingår i: Journal of chromatography. B. - : Elsevier. - 1570-0232 .- 1873-376X. ; 1021, s. 3-13
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Tidskriftsartikel (refereegranskat)abstract
- For protein analysis of biological samples, two major strategies are used today; mass spectrometry (MS) and antibody-based methods. Each strategy offers advantages and drawbacks. However, combining the two using an immunoenrichment step with MS analysis brings together the benefits of each method resulting in increased sensitivity, faster analysis and possibility of higher degrees of multiplexing. The immunoenrichment can be performed either on protein or peptide level and quantification standards can be added in order to enable determination of the absolute protein concentration in the sample. The combination of immunoenrichment and MS holds great promise for the future in both proteomics and clinical diagnostics. This review describes different setups of immunoenrichment coupled to mass spectrometry and how these can be utilized in various applications.
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| 6. |
- Claeson, Anna-Sara, 1974-, et al.
(författare)
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A standardized protocol for comparable analysis of GSH/GSSG by UHPLC-ESI-MSMS for human plasma
- 2019
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Ingår i: Journal of chromatography. B. - : Elsevier. - 1570-0232 .- 1873-376X. ; 1104, s. 67-72
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Tidskriftsartikel (refereegranskat)abstract
- Variability in the levels of GSH and GSSG in plasma is suggested to derive from inadequate pre-processing methods. The aim of this study was to develop a protocol for comparable and reliable measurements of GSH/GSSG. Venous blood from 8 healthy individuals were collected and divided into 7 different pre-processing procedures. For three of the samples an extraction mixture was added after 0 (baseline), 4 and 8 min and for three of the samples the extraction mixture was added at different times during defrost. A worst case scenario where a sample was left in a cool box during 6 h was also included. The samples were analyzed with UHPLC-ESIMSMS. A large difference in the levels of GSH and GSSG were identified and it was clearly associated with the sample handling procedures. A sample left untreated for 4 min will have significantly reduced amount of GSH. Stability tests showed that the level of GSH was reduced after 3 months in -80 degrees C.
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| 7. |
- El Beqqali, Aziza, et al.
(författare)
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Determination of AZD6118 in dog plasma samples utilizing microextraction by packed sorbent and liquid chromatography-electrospray ionization tandem mass spectrometry
- 2017
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Ingår i: Journal of chromatography. B. - : Elsevier BV. - 1570-0232 .- 1873-376X. ; 1043, s. 20-24
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Tidskriftsartikel (refereegranskat)abstract
- In this work, for the first time, a method has been developed for the determination of AZD6118, a candidate drug, in dog plasma samples. The method is based on microextraction by packed sorbent (MEPS) of the drug prior to liquid chromatography-electrospray ionization tandem mass spectrometry assay. Various important factors affecting MEPS performance were optimized, and under the optimized condition, a linear calibration curve in the concentration range of 20-25,000 nmol L-1 with a coefficient of determination over 0.99 was obtained. The back-calculated values of the calibration points showed good agreement with the theoretical concentrations (coefficients of variation percent between 0.3-3.8). The lower limit of quantification and limit of detection were 20.0 and 2.9 nmol L-1, respectively. The repeatability and accuracy of the method was evaluated by determination of quality control samples at three concentration levels (low, medium and high) using the developed method, and the results (coefficients of variation values were between 1.9% and 3.2%, relative recoveries ranged between 93.5-102.1%) confirm that a powerful method has been developed for the extraction and determination of the investigated drug in dog plasma.
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| 8. |
- El-Beqqali, Aziza, et al.
(författare)
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Molecularly imprinted polymer-sol-gel tablet toward micro-solid phase extraction : II. Determination of amphetamine in human urine samples by liquid chromatography tandem mass spectrometry
- 2017
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Ingår i: Journal of chromatography. B. - : Elsevier BV. - 1570-0232 .- 1873-376X. ; 1063, s. 130-135
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Tidskriftsartikel (refereegranskat)abstract
- Amphetamine selective molecularly imprinted sol-gel polymer tablets, MIP-tablets, for solid-phase micro extraction of biofluid samples were prepared. An acetonitrile solution of deuterated amphetamine template and silane precursor, 3-(propylmethacrylate) trimethoxysilane, was soaked into the pores of polyethylene tablet substrates and polymerized by an acid-catalysed sol-gel process. Application of the resultant MIP-tablets to extract amphetamine from human urine samples followed by LC-MS/MS analysis was investigated. The extraction protocol was optimised with respect to pH of sample, addition of sodium chloride, extraction time, desorption solvent and desorption time. The final analysis method determined amphetamine in human urine with a limit of detection (LOD) of 1.0 ng/mL and a lower limit of quantification (LLOQ) of 5 ng/mL. Validation demonstrated accuracy of the method was 91.0-104.0% and inter-assay precision was 4.8-8.5% (RSD). Extraction recovery was 80%. The MIP-tablets could be re-used and the same tablet could be employed for more than twenty extractions.
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| 9. |
- Ertürk, Gizem, et al.
(författare)
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From imprinting to microcontact imprinting-A new tool to increase selectivity in analytical devices.
- 2016
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Ingår i: Journal of Chromatography. B. - : Elsevier BV. - 1873-376X .- 1570-0232. ; 1021, s. 30-44
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Tidskriftsartikel (refereegranskat)abstract
- Molecular imprinting technology has been successfully applied to small molecular templates but a slow progress has been made in macromolecular imprinting owing to the challenges in natural properties of macromolecules, especially proteins. In this review, the macromolecular imprinting approaches are discussed with examples from recent publications. A new molecular imprinting strategy, microcontact imprinting is highlighted with its recent applications.
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| 10. |
- Haglind, Alfred, 1986-, et al.
(författare)
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Major signal suppression from metal ion clusters in SFC/ESI-MS : Cause and Effects
- 2018
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Ingår i: Journal of chromatography. B. - : Elsevier BV. - 1570-0232 .- 1873-376X. ; 1084, s. 96-105
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Tidskriftsartikel (refereegranskat)abstract
- The widening application area of SFC-MS with polar analytes and water-containing samples facilitates the use of quick and simple sample preparation techniques such as “dilute and shoot” and protein precipitation. This has also introduced new polar interfering components such as alkali metal ions naturally abundant in e.g. blood plasma and urine, which have shown to be retained using screening conditions in SFC/ESI-TOF-MS and causing areas of major ion suppression. Analytes co-eluting with these clusters will have a decreased signal intensity, which might have a major effect on both quantification and identification. When investigating the composition of the alkali metal clusters using accurate mass and isotopic pattern, it could be concluded that they were previously not described in the literature. Using NaCl and KCl standards and different chromatographic conditions, varying e.g. column and modifier, the clusters proved to be formed from the alkali metal ions in combination with the alcohol modifier and make-up solvent. Their compositions were [(XOCH3)n+X]+, [(XOH)n+X]+, [(X2CO3)n+X]+ and [(XOOCOCH3)n+X]+ for X= Na+ or K+ in ESI+. In ESI-, the clusters depended more on modifier, with [(XCl)n+Cl]- and [(XOCH3)n+OCH3]- mainly formed in pure methanol and [(XOOCH)n+OOCH]- when 20 mM NH4Fa was added.To prevent the formation of the clusters by avoiding methanol as modifier might be difficult, as this is a widely used modifier providing good solubility when analyzing polar compounds in SFC. A sample preparation with e.g. LLE would remove the alkali ions, however also introducing a time consuming and discriminating step into the method. Since the alkali metal ions were retained and affected by chromatographic adjustments as e.g. mobile phase modifications, a way to avoid them could therefore be chromatographic tuning, when analyzing samples containing them.
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| 11. |
- Hansson, Annelie, et al.
(författare)
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Equine in vivo-derived metabolites of the SARM LGD-4033 and comparison with human and fungal metabolites.
- 2018
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Ingår i: Journal of chromatography. B. - : Elsevier BV. - 1570-0232 .- 1873-376X. ; 1074-1075, s. 91-98
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Tidskriftsartikel (refereegranskat)abstract
- LGD-4033 has been found in human doping control samples and has the potential for illicit use in racehorses as well. It belongs to the pharmacological class of selective androgen receptor modulators (SARMs) and can stimulate muscle growth, much like anabolic steroids. However, SARMs have shown superior side effect profiles compared to anabolic steroids, which arguably makes them attractive for use by individuals seeking an unfair advantage over their competitors. The purpose of this study was to investigate the metabolites formed from LGD-4033 in the horse in order to find suitable analytical targets for doping controls. LGD-4033 was administered to three horses after which plasma and urine samples were collected and analyzed for metabolites using ultra high performance liquid chromatography coupled to a high resolution mass spectrometer. In horse urine, eight metabolites, both phase I and phase II, were observed most of which had not been described in other metabolic systems. Six of these were also detected in plasma. The parent compound was detected in plasma, but not in non-hydrolyzed urine. The longest detection times were observed for unchanged LGD-4033 in plasma and in urine hydrolyzed with β-glucuronidase and is thus suggested as the analytical target for doping control in the horse. The metabolite profile determined in the horse samples was also compared to those of human urine and fungal incubate from Cunninghamella elegans. The main human metabolite, dihydroxylated LGD-4033, was detected in the horse samples and was also produced by the fungus. However, it was a not a major metabolite for horse and fungus, which highlights the importance of performing metabolism studies in the species of interest.
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| 12. |
- Höjer Holmgren, Karin, et al.
(författare)
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Screening of nerve agent markers with hollow fiber-chemosorption of phosphonic acids
- 2016
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Ingår i: Journal of chromatography. B. - : Elsevier BV. - 1570-0232 .- 1873-376X. ; 1033-1034, s. 97-105
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Tidskriftsartikel (refereegranskat)abstract
- This report describes a method developed for extracting nerve gas markers such as phosphonic acids from urine and other aqueous samples. It involves single-step microextraction with chemosorption to hollow fibers that have been pre-soaked in a solution containing a derivatization reagent (3,5 triflouro methyl benzene diazomethane). The derivatives it forms with phosphonic acids can be sensitively detected by mass spectrometric detectors operating in negative chemical ionization (NCI) mode. Limits of quantification obtained in analyses of water and urine extracts by GC/MS in negative chemical ionization and selected ion monitoring mode were 0.1–10 and 0.5–10 ng/mL, respectively. Pentaflourophenyl diazomethane can also be used as a derivatization reagent, and the micro-extracts (which generate low background signals) can be sensitively analyzed by GC–MS/MS in NCI selected reaction monitoring (SRM) mode, using two specific transitions for both reagents. Thus, this sensitive approach can be flexibly modified to obtain confirmatory information, or address potential problems caused by interferences in some samples.
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| 13. |
- Jagadeesan, Kishore, et al.
(författare)
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Multiplexed MALDI-MS arrays for screening of MIP solid phase extraction materials
- 2016
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Ingår i: Journal of chromatography. B. - : Elsevier. - 1570-0232 .- 1873-376X. ; 1021, s. 213-220
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Tidskriftsartikel (refereegranskat)abstract
- Technology that facilitates rapid investigation of solid phase extraction protocols using very small amounts of sorbent can save both time and money. The microfabricated ISET (Integrated Selective Enrichment Target) interfaced with MALDI mass spectrometry is able to provide an efficient, economic and generic optimization process for SPE sample preparation. The SPE is performed in a rapid and parallel fashion, with a processing time off only 2h per ISET with 96 samples. Each of the 96 wells on the ISET can hold 600nL of SPE sorbent. The ability to work with small amounts of sorbent and samples in the ISET platform provides a big advantage when developing affinity sorbents, such as molecularly imprinted polymers (MIPs). Here it is demonstrated that an amount of 25mg phosphoserine imprinted MIP (pS-MIP) sorbent can allow for analysis of more than 500 ISET nanovials using a multitude of different conditions. In the presented case, the multiplexed experiments allowed for early discovery of unspecific interactions and subsequent minimization of these, resulting in a protocol that provided improved enrichment of phosphopeptides.
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| 14. |
- Kip, A E, et al.
(författare)
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Quantification of miltefosine in peripheral blood mononuclear cells by high-performance liquid chromatography-tandem mass spectrometry.
- 2015
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Ingår i: Journal of chromatography. B. - : Elsevier BV. - 1570-0232 .- 1873-376X. ; 998-999, s. 57-62
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Tidskriftsartikel (refereegranskat)abstract
- Phagocytes, the physiological compartment in which Leishmania parasites reside, are the main site of action of the drug miltefosine, but the intracellular pharmacokinetics of miltefosine remain unexplored. We developed a bioanalytical method to quantify miltefosine in human peripheral blood mononuclear cells (PBMCs), expanding from an existing high performance liquid chromatography-tandem mass spectrometry method for the quantification of miltefosine in plasma. The method introduced deuterated miltefosine as an internal standard. Miltefosine was extracted from PBMC pellets by addition of 62.5% methanol. Supernatant was collected, evaporated and reconstituted in plasma. Chromatographic separation was performed on a reversed phase C18 column and detection with a triple-quadrupole mass spectrometer. Miltefosine was quantified using plasma calibration standards ranging from 4 to 1000ng/mL. This method was validated with respect to its PBMC matrix effect, selectivity, recovery and stability. No matrix effect could be observed from the PBMC content (ranging from 0.17 to 26.3×10(6)PBMCs) reconstituted in plasma, as quality control samples were within 3.0% of the nominal concentration (precision less than 7.7%). At the lower limit of quantitation of 4 ng/mL plasma, corresponding to 0.12ng/10(6) PBMCs in a typical clinical sample, measured concentrations were within 8.6% of the nominal value. Recovery showed to be reproducible as adding additional pre-treatment steps did not increase the recovery with more than 9%. This method was successfully applied to measure intracellular miltefosine concentrations in PBMC samples from six cutaneous leishmaniasis patients up to one month post-treatment.
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| 15. |
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| 16. |
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| 17. |
- Magiera, Sylwia, et al.
(författare)
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Salting-out assisted extraction method coupled with hydrophilic interaction liquid chromatography for determination of selected beta-blockers and their metabolites in human urine
- 2016
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Ingår i: Journal of chromatography. B. - : ELSEVIER SCIENCE BV. - 1570-0232 .- 1873-376X. ; 1022, s. 93-101
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Tidskriftsartikel (refereegranskat)abstract
- In this study, a new analytical method was developed and validated for the simultaneous analysis of beta-blockers (metoprolol, propranolol, carvedilol) and their metabolites (5-hydroxycarvedilol, O-desmethylcarvedilol, alpha-hydroxymetoprolol, O-desmethylmetoprolol, 5-hydroxypropranolol) in human urine. A salting-out assisted liquid-liquid extraction (SALLE) procedure was used for sample preparation. Several parameters affecting the extraction efficiency and method sensitivity including the type and volume of the extraction solvent, the type and quantity of the inorganic salt, extraction time and sample pH were investigated. Hydrophilic interaction liquid chromatography-ultraviolet detection (HILIC-UV) was used for the determination of allanalytes. During method development, the effects of mobile phase components (type, pH, concentration of salt, organic modifier type and content, flow rate, column temperature) on the retention and separation of beta-blockers and metabolites on the five different HILIC columns were examined. The method was linear for concentrations ranging from 0.1 to 8.0 mu g/mL, with determination coefficients higher than 0.993 for all analytes. The limits of quantification were in the range from 0.1 to 0.2 mu g/mL. Intra- and inter-day precision ranged from 0.1 to 8.9%, and accuracy was within +/- 13% interval for all analytes. Under the optimized conditions, extraction efficiency was greater than 83.4% for determined compounds. The validated method was then applied to the measurement of beta-blockers and their metabolites in human urine samples. (C) 2016 Elsevier B.V. All rights reserved.
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| 18. |
- Moczko, Ewa, et al.
(författare)
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Epitope approach in molecular imprinting of antibodies
- 2019
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Ingår i: Journal of chromatography. B. - : Elsevier. - 1570-0232 .- 1873-376X. ; 1124, s. 1-6
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Tidskriftsartikel (refereegranskat)abstract
- Herein an approach to prepare molecularly imprinted polymer nanoparticles (nanoMlPs) with specific binding affinity for antibodies is reported. The process relied on the covalent immobilization of the template (whole immunoglobulin G (IgG), Fc domain of human IgG and peptide epitope) onto the surface of a solid support, polymerization and affinity separation of nanoMlPs. The binding between nanoMIPs and their corresponding templates was analyzed and evaluated as being in sub-nanomolar and nano-molar range. The nanoMlPs prepared for Fc domain and epitope demonstrated a specific recognition of both human and goat IgGs, therefore they could be considered as a synthetic analogue of protein A and benefit from its intrinsic stability, short time and low cost of preparation.
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| 19. |
- Moein, Mohammad Mandi, et al.
(författare)
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Bioanalytical method development and validation : Critical concepts and strategies
- 2017
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Ingår i: Journal of chromatography. B. - : Elsevier BV. - 1570-0232 .- 1873-376X. ; 1043, s. 3-11
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Tidskriftsartikel (refereegranskat)abstract
- Bioanalysis is an essential part in drug discovery and development. Bioanalysis is related to the analysis of analytes (drugs, metabolites, biomarkers) in biological samples and it involves several steps from sample collection to sample analysis and data reporting. The first step is sample collection from clinical or preclinical studies; then sending the samples to laboratory for analysis. Second step is sample clean-up (sample preparation) and it is very important step in bioanalysis. In order to reach reliable results, a robust and stable sample preparation method should be applied. The role of sample preparation is to remove interferences from sample matrix and improve analytical system performance. Sample preparation is often labor intensive and timeconsuming. Last step is the sample analysis and detection. For separation and detection, liquid chromatography-tandem mass spectrometry (LC MS/MS) is method of choice in bioanalytical laboratories. This is due to high selectivity and high sensitivity of the LC MS/MS technique. In addition the information about the analyte chemical structure and chemical properties is important to be known before the start of bioanalytical work. This review provides an overview of bioanalytical method development and validation. The main principles of method validation will be discussed. In this review GLP and regulated bioanalysis are described. Commonly used sample preparation techniques will be presented. In addition the role of LC MS/MS in modern bioanalysis will be discussed. In the present review we have our focus on bioanalysis of small molecules.
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| 20. |
- Moein, Mohammad Mandi, et al.
(författare)
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Three-phase molecularly imprinted sol-gel based hollow fiber liquid-phase microextraction combined with liquid chromatography-tandem mass spectrometry for enrichment and selective determination of a tentative lung cancer biomarker
- 2015
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Ingår i: Journal of chromatography. B. - : Elsevier BV. - 1570-0232 .- 1873-376X. ; 995, s. 38-45
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Tidskriftsartikel (refereegranskat)abstract
- In the present study, the modification of a polysulfone hollow fiber membrane with in situ molecularly imprinted sol-gel process (as a novel and one-step method) was prepared and investigated. 3-(propylmethaaylate)trimethoxysilane (3PMTMOS) as an inorganic precursor was used for preparation of molecularly imprinted sol-gel. The modified molecularly imprinted sol-gel hollow fiber membrane (MSHM) was used for the liquid-phase microextraction (LPME) of hippuric acid (HA) in human plasma and urine samples. MSHM as a selective, robust, and durable tool was used for at least 50 extractions without significant decrease in the extraction efficiency. The non-molecularly imprinted sol-gel hollow fiber membrane (NSHM) as blank hollow fiber membrane was prepared by the same process, only without HA. To achieve the best condition, influential parameters on the extraction efficiency were thoroughly investigated. The capability of this robust, green, and simple method for extraction of HA was successfully accomplished with LC/MS/MS. The limits of detection (LOD) and quantification (LOQ) in human plasma and urine samples were 0.3 and 1.0 nmol L-1, respectively. The standard calibration curves were obtained within the concentration range 1-2000 nmol L-1 for HA in human plasma and urine. The coefficients of determination (r(2)) were >= 0.998. The obtained data exhibited recoveries were higher than 89% for the extraction of HA in human plasma and urine samples.
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| 21. |
- Ohlson, Sten, et al.
(författare)
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Direct analysis - no sample preparation - of bioavailable cortisol in human plasma by weak affinity chromatography (WAC)
- 2017
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Ingår i: Journal of chromatography. B. - : Elsevier. - 1570-0232 .- 1873-376X. ; 1061, s. 438-444
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Tidskriftsartikel (refereegranskat)abstract
- Pre-analytical treatment of blood plasma is a time consuming and often rate limiting step in the workflow of LC/MS analysis. We present in this pilot study a new approach for quantitative LC/MS based on weak affinity chromatography (WAC) of crude plasma. The steroid hormone cortisol was selected as a clinically relevant biomarker, as it currently requires extensive pre-analytical preparation. A WAC unit with saturating, immobilized albumin as a prototypic weak binder was used in combination with an ion-funnel MS/MS detector to perform zonal affinity chromatography of cortisol directly from a plasma sample, followed by quantitative multiple reaction monitoring (MRM). This procedure also allowed us to determine the amount of bioavailable cortisol in the clinical plasma sample which is of significant therapeutic interest. This WAC-MS approach showed an excellent correlation (R-2 = 0.86 (P < 0.0001 (highly significant); n = 60) with a state-of-the-art, clinical competitive immunoassay procedure for plasma cortisol analysis. With integration of WAC into LC/MS workflow, it may be possible to both accelerate and improve assay performance by eliminating the sample extraction step. Preliminary data with other steroid hormones indicate that WAC-MS can be applied to various biomolecules using a plasma transport protein such as albumin.
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| 22. |
- Primikyri, Alexandra, et al.
(författare)
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Method development and validation for the quantitation of the complement inhibitor Cp40 in human and cynomolgus monkey plasma by UPLC-ESI-MS
- 2017
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Ingår i: Journal of chromatography. B. - : Elsevier BV. - 1570-0232 .- 1873-376X. ; 1041, s. 19-26
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Tidskriftsartikel (refereegranskat)abstract
- Cp40 is a 14-amino acid cyclic analog of the peptidic complement inhibitor compstatin that binds with sub-nanomolar affinity to complement component C3 and has already shown promise in various models of complement-related diseases. The preclinical and clinical development of this compound requires a robust, accurate, and sensitive method for quantitatively monitoring Cp40 in biological samples. In this study, we describe the development and validation of an ultra-high performance liquid chromatography electrospray mass spectrometry method for the quantitation of Cp40 in human and non-human primate (NHP) plasma. Isotope-labeled Cp40 was used as an internal standard, allowing for the accurate and absolute quantitation of Cp40. Labeled and non-labeled Cp40 were extracted from plasma using reversed phase-solid phase extraction, with recovery rates exceeding 80%, indicating minor matrix effects. The triply charged states of Cp40 and isotope-labeled Cp40 were detected at m/z 596.60 and 600.34, respectively, via a Q-TOF mass spectrometer and were used for quantitation. The method was linear in the range of 0.18-3.58 mu g/mL (r(2) >= 0.99), with precision values below 0.71% in NHP and 0.77% in human plasma. The accuracy of the method ranged from -2.17% to 17.99% in NHP and from -0.26% to 15.75% in 'human plasma. The method was successfully applied to the quantitation of Cp40 in cynomolgus monkey plasma after an initial intravenous bolus of 2 mg/kg followed by repetitive subcutaneous administration at 1 mg/kg. The high reproducibility, accuracy, and robustness of the method developed here render it suitable for drug monitoring of Cp40, and potentially other compstatin analogs, in both human and NHP plasma samples during pharmacokinetic and pharmacodynamic studies.
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| 23. |
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| 24. |
- Quell, Jan D., et al.
(författare)
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Automated pathway and reaction prediction facilitates in silico identification of unknown metabolites in human cohort studies
- 2017
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Ingår i: Journal of Chromatography B: Analytical Technologies in the Biomedical and Life Sciences. - : Elsevier BV. - 1570-0232 .- 1873-376X. ; 1071, s. 58-67
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Tidskriftsartikel (refereegranskat)abstract
- Identification of metabolites in non-targeted metabolomics continues to be a bottleneck in metabolomics studies in large human cohorts. Unidentified metabolites frequently emerge in the results of association studies linking metabolite levels to, for example, clinical phenotypes. For further analyses these unknown metabolites must be identified. Current approaches utilize chemical information, such as spectral details and fragmentation characteristics to determine components of unknown metabolites. Here, we propose a systems biology model exploiting the internal correlation structure of metabolite levels in combination with existing biochemical and genetic information to characterize properties of unknown molecules.Levels of 758 metabolites (439 known, 319 unknown) in human blood samples of 2279 subjects were measured using a non-targeted metabolomics platform (LC-MS and GC-MS). We reconstructed the structure of biochemical pathways that are imprinted in these metabolomics data by building an empirical network model based on 1040 significant partial correlations between metabolites. We further added associations of these metabolites to 134 genes from genome-wide association studies as well as reactions and functional relations to genes from the public database Recon 2 to the network model. From the local neighborhood in the network, we were able to predict the pathway annotation of 180 unknown metabolites. Furthermore, we classified 100 pairs of known and unknown and 45 pairs of unknown metabolites to 21 types of reactions based on their mass differences. As a proof of concept, we then looked further into the special case of predicted dehydrogenation reactions leading us to the selection of 39 candidate molecules for 5 unknown metabolites. Finally, we could verify 2 of those candidates by applying LC-MS analyses of commercially available candidate substances. The formerly unknown metabolites X-13891 and X-13069 were shown to be 2-dodecendioic acid and 9-tetradecenoic acid, respectively.Our data-driven approach based on measured metabolite levels and genetic associations as well as information from public resources can be used alone or together with methods utilizing spectral patterns as a complementary, automated and powerful method to characterize unknown metabolites.
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| 25. |
- Romson, Joakim, et al.
(författare)
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An automated system for CE-MALDI and on-target digestion under a fluorocarbon lid applied on spermatophore proteins from Pieris napi
- 2019
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Ingår i: Journal of chromatography. B. - : ELSEVIER SCIENCE BV. - 1570-0232 .- 1873-376X. ; 1104, s. 228-233
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Tidskriftsartikel (refereegranskat)abstract
- A method for off-line CE-MALDI-TOF-MS and MS2, and on-target digestion under a fluorocarbon lid was developed and applied for the analysis of proteins in the spermatophore of the butterfly Pieris napi. Fractionation revealed many peptides otherwise not detected or resolved. Automated fractionation was performed with an in-lab developed robotic system, and automated on-target tryptic digestion under a fluorocarbon lid was demonstrated with the same system. Fractionation onto a pre-structured MALDI-concentration plate facilitated aligned deposition of trypsin and MALDI-matrix with the deposited sample, also under the fluorocarbon lid. Some indications of indigenous proteolysis of spermatophore proteins were seen, and searching MS2 spectra suggested three tentative sequence homologies to P. rapae. The study demonstrates the functionality of the lab-made robot. Detailed manufacturing instructions and code are provided. The feasibility of automated on-target digestion under a fluorocarbon lid, and the usefulness of a structured concentration plate in CE-MALDI fractionation was shown. Further, it constitutes a preliminary study of P. napi spermatophore proteins.
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| 26. |
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| 27. |
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| 28. |
- Svahn, Ola, 1970-, et al.
(författare)
-
Increased electrospray ionization intensities and expanded chromatographic possibilities for emerging contaminants using mobile phases of different pH
- 2016
-
Ingår i: Journal of chromatography. B. - 1570-0232 .- 1873-376X. ; 1033-1034, s. 128-137
-
Tidskriftsartikel (refereegranskat)abstract
- In this work the habitual behaviour of low pH in environmental organic trace analysis is challenged by investigating the full potential of building a multi-component UHPLC-ESI-MS/MS method adapted to cover common emerging contaminants of many different polarities, minimizing the elements of compromise in the performance of the final analytical separation and detection. Contributes have been made by taking advantage of common commercially available technology in understanding the impact from solvent components and the ionization of analytes which can facilitate future development of robust, sensitive and precise UHPLC-MS/MS methods. All contaminants were evaluated and optimized without prejudices regarding historical residence in terms of chromatographic conditions and ESI mode; increasing multi-method's flexibility that can be implemented in routine analysis in response to new requests as well as to emerging contaminants yet to be discovered. Our data strongly supports the questioning of the assumption that equilibrium concentrations of ions in solution reflect those produced during the electrospray process. ESI responses of [M+H](+) and limits of detection were comparable, or often better at high pH compared to acidic eluents. Presence of nitrogen basic groups such as tertiary and secondary amines in a compound increased the intensity of the ESI+ signal, and was even further elevated in basic eluent. The proton affinity probably changes for many nitrogen-containing compounds during the ionization process, making the gas-phase processes very important in generation of these ions by ESI+. There were also an unexpected large number of compounds showing their highest response at pH 7 and weak ionic strength. A flow optimized, buffert free, neutral UHPLC-MS/MS method enhanced the sensitivity for the environmental important synthetic hormone ethinyl estradiol significantly.
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| 29. |
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| 30. |
- Weisser, Johan J., et al.
(författare)
-
A novel method for analysing key corticosteroids in polar bear (Ursus maritimus) hair using liquid chromatography tandem mass spectrometry
- 2016
-
Ingår i: Journal of chromatography. B. - 1570-0232 .- 1873-376X. ; 1017, s. 45-51
-
Tidskriftsartikel (refereegranskat)abstract
- This paper presents the development and evaluation of a methodology for extraction, clean-up and analysis of three key corticosteroids (aldosterone, cortisol and corticosterone) in polar bear hair. Such a methodology can be used to monitor stress biomarkers in polar bears and may provide as a useful tool for long-term and retrospective information. We developed a combined pressurized liquid extraction (PLE)-solid phase extraction (SPE) procedure for corticosteroid extraction and clean-up followed by high pressure liquid chromatography tandem mass spectrometry (HPLC-MS/MS) analysis. This procedure allows for the simultaneous determination of multiple steroids, which is in contrast to previous polar bear studies based on ELISA techniques. Absolute method recoveries were 81%, 75% and 60% for cortisol, corticosterone and aldosterone, respectively. We applied the developed method on a hair sample pooled from four East Greenland polar bears. Herein cortisol and corticosterone were successfully determined in levels of 0.32 +/- 0.02 ng/g hair and 0.13 +/- 0.02 ng/g hair, respectively. Aldosterone was below limit of detection (LOD<0.17 ng/g). The cortisol hair concentration found in these East Greenland polar bears was consistent with cortisol levels previously determined in the Southern Hudson Bay and James Bay in Canada using ELISA kits. (C) 2016 Elsevier B.V. All rights reserved.
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| 31. |
- Wierzbicka, Roksana, et al.
(författare)
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Determination of alkylresorcinols and their metabolites in biological samples by gas chromatography-mass spectrometry
- 2015
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Ingår i: Journal of Chromatography B. - : Elsevier BV. - 1570-0232 .- 1873-376X. ; 1000, s. 120-129
-
Tidskriftsartikel (refereegranskat)abstract
- High throughput GC-MS methods for quantification of alkylresorcinols (AR), biomarkers of whole grain wheat and rye intake, in plasma and adipose tissue and their metabolites in urine were developed and optimised. Alkylresorcinols in plasma (200 mu L) and adipose tissues (10-50 mg) were extracted with diethyl ether, whereas main AR metabolites such as DHBA and DHPPA and newly identified metabolites in urine (50 mu L) were extracted with ethyl acetate after enzymatic deconjugation. All extracts were purified on OASIS-MAX solid phase extraction cartridges. Plasma and adipose tissue sample extracts were then derivatised with trifluoroacetic anhydride and reconstituted in undecane, whereas AR metabolites in urine samples were derivatised with BSTFA+TMCS (99:1, v/v, 100 mu L). Prepared samples were quantified by GC-MS (EI-SIM). Analysis of all compounds in the different matrices showed good selectivity, sensitivity, linearity, precision (<15% within and between batches), adequate recovery (75-108%), and short total run time (10-12 min). The methods developed are applicable to large-scale sample sets such as epidemiological studies. (C) 2015 The Authors. Published by Elsevier B.V.
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| 32. |
- Yang, Liu, et al.
(författare)
-
Sorbent, device, matrix and application in microextraction by packed sorbent (MEPS) : A review
- 2017
-
Ingår i: Journal of chromatography. B. - : Elsevier BV. - 1570-0232 .- 1873-376X. ; 1043, s. 33-43
-
Forskningsöversikt (refereegranskat)abstract
- Microextraction by packed sorbent (MEPS) is a new miniaturized form of solid-phase extraction and it is a green sample pretreatment technology. MEPS has been widely accepted and used by several research groups online or offline as a sample preparation technique before instrument analysis. MEPS reduces the sample handling time and organic solvent consumption. MEPS is suitable for small sample volumes and can easily be connected with different chromatographic techniques without modification. The sorbent bed in MEPS is integrated into a liquid handling syringe that allows for low void volume sample manipulations either manually or in combination with laboratory robotics. MEPS is a simple, fast and robust sample preparation technique with several advantages, miniaturization, automation, fast operation course, on-line coupling with analytical instruments and low-cost operation with less solvent and low sample consumption. Sorbent type, device, and matrix are important factors in MEPS research and applications. The performance of MEPS has recently been illustrated by online with liquid chromatography-mass spectrometry and gas chromatography-mass spectrometry assays for pharmaceutical, environmental, and food analyses. This paper deals with MEPS device-optimized sorbent, sample matrix, and application. The progress and potential development of the technique are also discussed.
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| 33. |
- Aziz, Mohd Yusmaidie, 1984, et al.
(författare)
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LC-MS/MS quantitation of antimalarial drug piperaquine and metabolites in human plasma
- 2017
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Ingår i: Journal of chromatography. B. - : Elsevier BV. - 1570-0232. ; 1063, s. 253-258
-
Tidskriftsartikel (refereegranskat)abstract
- Purpose: This study aimed to develop a sensitive, quantitative assay for the antimalarial piperaquine (PQ) and its metabolites M1 and M2 in human plasma. Results: Analytes were gradiently separated on a C18 column and detected with a Sciex API 4000 MS/MS with an ESI source operated in the positive ion mode with deuterated PQ as internal standard. The response was linear in the range 3.9-2508 nM with a runtime of 7.0 min per sample. The method was applied to clinical samples from healthy volunteers. Conclusion: This LC-MS/MS method for the simultaneous quantitation of PQ and two of its metabolites in plasma may prove helpful for assessment of metabolite safety issues in vivo.
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| 34. |
- Sundell, Jesper, et al.
(författare)
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Simultaneous quantification of four first line antitubercular drugs and metabolites in human plasma by hydrophilic interaction chromatography and tandem mass spectrometry
- 2019
-
Ingår i: Journal of Chromatography B: Analytical Technologies in the Biomedical and Life Sciences. - : Elsevier BV. - 1570-0232. ; 1105, s. 129-135
-
Tidskriftsartikel (refereegranskat)abstract
- Co-infection of tuberculosis in HIV-patients is a major health concern worldwide and especially so in Sub-Saharan Africa. To enhance the study of potential drug-drug interactions when simultaneously treating the two infections, a liquid chromatography tandem mass spectrometry method was developed for the quantitation of the four first line anti-tuberculosis drugs isoniazid, rifampicin, pyrazinamide, ethambutol and four of their major metabolites in human plasma. Analytes were extracted from 200 μL of plasma using a sequential liquid-liquid extraction with ethyl acetate at neutral and acidic pH. The combined extracts were analyzed by liquid chromatography with mass spectrometric detection in a multiple reaction monitoring mode. The chromatographic separation was performed on a hydrophilic interaction column using a stepwise gradient with two mobile phases consisting of water with 0.3% formic acid and methanol with 0.3% formic acid, respectively. The total run time of each analysis was 4 min. The lower limit of quantification applied was 40 ng/mL for ethambutol, acetylisoniazid and 25-desacetylrifampicin, 60 ng/mL for 5-hydroxypyrazinamide, 80 ng/mL for isoniazid and isonicotinic acid, 200 ng/mL for rifampicin and 320 ng/mL for pyrazinamide. The method was validated according to US Food and Drug Administration guidance. The method exhibited adequate accuracy (87.1–114.9%), precision (CV < 12.8%) and specificity. Recovery and matrix effect were consistent (CV < 11.9%). The extracted samples were stable in the autosampler at 8 °C for up to 24 h as well as after three freeze-thaw cycles (recovery > 86.3%). The method has been shown to be robust for the analysis of the stated drugs and metabolites in human plasma obtained from 73 patients receiving these four first line anti-tuberculosis drugs. © 2018 Elsevier B.V.
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| 35. |
- Svahn, Ola, et al.
(författare)
-
Increased electrospray ionization intensities and expanded chromatographic possibilities for emerging contaminants using mobile phases of different pH
- 2016
-
Ingår i: Journal of chromatography. B. - : Elsevier BV. - 1570-0232. ; 1033-1034, s. 128-137
-
Tidskriftsartikel (refereegranskat)abstract
- In this work the habitual behaviour of low pH in environmental organic trace analysis is challenged by investigating the full potential of building a multi-component UHPLC-ESI-MS/MS method adapted to cover common emerging contaminants of many different polarities, minimizing the elements of compromise in the performance of the final analytical separation and detection. Contributes have been made by taking advantage of common commercially available technology in understanding the impact from solvent components and the ionization of analytes which can facilitate future development of robust, sensitive and precise UHPLC-MS/MS methods. All contaminants were evaluated and optimized without prejudices regarding historical residence in terms of chromatographic conditions and ESI mode; increasing multi-method's flexibility that can be implemented in routine analysis in response to new requests as well as to emerging contaminants yet to be discovered. Our data strongly supports the questioning of the assumption that equilibrium concentrations of ions in solution reflect those produced during the electrospray process. ESI responses of [M+H](+) and limits of detection were comparable, or often better at high pH compared to acidic eluents. Presence of nitrogen basic groups such as tertiary and secondary amines in a compound increased the intensity of the ESI+ signal, and was even further elevated in basic eluent. The proton affinity probably changes for many nitrogen-containing compounds during the ionization process, making the gas-phase processes very important in generation of these ions by ESI+. There were also an unexpected large number of compounds showing their highest response at pH 7 and weak ionic strength. A flow optimized, buffert free, neutral UHPLC-MS/MS method enhanced the sensitivity for the environmental important synthetic hormone ethinyl estradiol significantly.
|
|
| 36. |
- Weisser, Johan J., et al.
(författare)
-
A novel method for analysing key corticosteroids in polar bear (Ursus maritimus) hair using liquid chromatography tandem mass spectrometry
- 2016
-
Ingår i: Journal of chromatography. B. - : Elsevier BV. - 1570-0232. ; 1017, s. 45-51
-
Tidskriftsartikel (refereegranskat)abstract
- This paper presents the development and evaluation of a methodology for extraction, clean-up and analysis of three key corticosteroids (aldosterone, cortisol and corticosterone) in polar bear hair. Such a methodology can be used to monitor stress biomarkers in polar bears and may provide as a useful tool for long-term and retrospective information. We developed a combined pressurized liquid extraction (PLE)-solid phase extraction (SPE) procedure for corticosteroid extraction and clean-up followed by high pressure liquid chromatography tandem mass spectrometry (HPLC-MS/MS) analysis. This procedure allows for the simultaneous determination of multiple steroids, which is in contrast to previous polar bear studies based on ELISA techniques. Absolute method recoveries were 81%, 75% and 60% for cortisol, corticosterone and aldosterone, respectively. We applied the developed method on a hair sample pooled from four East Greenland polar bears. Herein cortisol and corticosterone were successfully determined in levels of 0.32 +/- 0.02 ng/g hair and 0.13 +/- 0.02 ng/g hair, respectively. Aldosterone was below limit of detection (LOD<0.17 ng/g). The cortisol hair concentration found in these East Greenland polar bears was consistent with cortisol levels previously determined in the Southern Hudson Bay and James Bay in Canada using ELISA kits. (C) 2016 Elsevier B.V. All rights reserved.
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| 37. |
- Gruenhagen, Jan Henrik, et al.
(författare)
-
International experience, growth aspirations, and the internationalisation of new ventures
- 2018
-
Ingår i: Journal of International Entrepreneurship. - : Springer. - 1570-7385 .- 1573-7349. ; 16:3, s. 421-440
-
Tidskriftsartikel (refereegranskat)abstract
- The aim of this paper is to investigate the impact of the breadth and depth of international experience on subsequent new venture internationalisation and to what extent growth aspirations moderate these relationships. Drawing upon previous literature on international new ventures, human capital and growth aspirations, we tested our hypotheses using longitudinal data from the Comprehensive Australian Study of Entrepreneurial Emergence (CAUSEE). Our results support the hypothesis that breadth of international experience has a positive impact on internationalisation. Depth of international experience on its own does not predict subsequent internationalisation activities. However, results support our hypothesis that the interplay of a high growth aspiration and depth of international experience has a positive effect on internationalisation activities. Our study contributes to the research stream on new venture internationalisation by distinguishing between breadth and depth of international experience, suggesting that these dimensions are differentially linked to internationalisation. Further, we test for interaction effects between international experience and growth aspirations. We thereby add to the knowledge by illustrating that some types of human capital are only utilised when accompanied by growth aspirations.
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