| 1. |
- Abrahamsson, Victor, et al.
(författare)
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Supercritical fluid extraction of lipids from linseed with on-line evaporative light scattering detection.
- 2015
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Ingår i: Analytica Chimica Acta. - : Elsevier BV. - 1873-4324 .- 0003-2670. ; 853, s. 320-327
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Tidskriftsartikel (refereegranskat)abstract
- Supercritical fluid extraction (SFE) is a green alternative method of extraction for neutral lipids in seeds compared to conventional methods utilizing organic solvents. In this work, a novel method where SFE is hyphenated with an evaporative light scattering detector is presented. The method was subsequently applied to determine lipid content in crushed linseed. The new method enables rapid quantification of extracted lipids as well as be ability to continuously monitor the extraction rate in real-time, thus being able to determine the time point of completed extraction. Both the detector and the method was validated. The results show that any of several tested oils can be used to calibrate the detection method for the determination of lipids extraction from linseed. The overall method repeatability and intermediate precision was 2.6% relative standard deviations. The extracted amount was significantly less than that obtained using the standard method of Soxhlet with petroleum ether, 26.0±0.4% (95% CI, n=9) compared to 32.3±1.3% (95% CI, n=3) of extracted amounts. It was found that channeling effects were present, and by either performing sequential repeated extractions with decompression in-between or by using a relatively large vessel a more complete extraction could be obtained. Interestingly, a substantially higher extracted amount (approximately 50%) was obtained compared to both a single extraction by SFE and the Soxhlet method. Therefore, it is recommended that an additional extraction including a rapid decompression in-between should be included in the validation of a method using supercritical fluid extraction, in order to either rule out channeling effects or to acquire a full recovery.
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| 2. |
- Ahmadi, Mazaher, et al.
(författare)
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Nanomaterials as sorbents for sample preparation in bioanalysis : A review
- 2017
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Ingår i: Analytica Chimica Acta. - : Elsevier BV. - 0003-2670 .- 1873-4324. ; 958, s. 1-21
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Forskningsöversikt (refereegranskat)abstract
- In recent years, application of nanomaterials as sorbent has gained the attention of researchers in bioanalysis. Different nanomaterials have been utilized as the sorbent in extraction techniques such as solid phase extraction, dispersive solid phase extraction, magnetic solid phase extraction, microextraction by packed sorbent, solid phase microextraction, dispersive pt-solid phase extraction, and stir bar sorptive extraction. In the present review, different nanomaterials which have recently been utilized as sorbent for bioanalysis are classified into six main groups, namely metallic, metallic and mixed oxide, magnetic, carbonaceous, silicon, and polymer-based nanomaterials. Application of these nanomaterials in different extraction techniques for bioanalysis has been reviewed. This study shows that magnetic nanomaterials have gained significant attention owing to their magnetic separation ability. In addition, the present review shows that there is a lack in the application of nanomaterials for on-line analysis procedures, most probably due to some intrinsic properties of nanomaterials such as spontaneous agglomeration.
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| 3. |
- Ali Soomro, Razium, et al.
(författare)
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Highly sensitive determination of atropine using cobalt oxide nanostructures: Influence of functional groups on the signal sensitivity
- 2016
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Ingår i: Analytica Chimica Acta. - : ELSEVIER SCIENCE BV. - 0003-2670 .- 1873-4324. ; 948, s. 30-39
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Tidskriftsartikel (refereegranskat)abstract
- This study describes sensitive determination of atropine using glassy carbon electrodes (GCE) modified with Co3O4 nanostructures. The as-synthesised nanostructures were grown using cysteine (CYS), glutathione (GSH) and histidine (HYS) as effective templates under hydrothermal action. The obtained morphologies revealed interesting structural features, including both cavity-based and flower-shaped structures. The as-synthesised morphologies were noted to actively participate in electro-catalysis of atropine (AT) drug where GSH-assisted structures exhibited the best signal response in terms of current density and over-potential value. The study also discusses the influence of functional groups on the signal sensitivity of atropine electro-oxidation. The functionalisation was carried with the amino acids originally used as effective templates for the growth of Co3O4 nanostructures. The highest increment was obtained when GSH was used as the surface functionalising agent. The GSH-functionalised Co3O4-modified electrode was utilised for the electro-chemical sensing of AT in a concentration range of 0.01 -0.46 mu M. The developed sensor exhibited excellent working linearity (R-2 = 0.999) and signal sensitivity up to 0.001 mu M of AT. The noted high sensitivity of the sensor is associated with the synergy of superb surface architectures and favourable interaction facilitating the electron transfer kinetics for the electro-catalytic oxidation of AT. Significantly, the developed sensor demonstrated excellent working capability when used for AT detection in human urine samples with strong anti-interference potential against common co-existing species, such as glucose, fructose, cysteine, uric acid, dopamine and ascorbic acid. (C) 2016 Elsevier B.V. All rights reserved.
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| 4. |
- Arrhenius, Karine, et al.
(författare)
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Suitability of different containers for the sampling and storage of biogas and biomethane for the determination of the trace-level impurities - A review
- 2016
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Ingår i: Analytica Chimica Acta. - : Elsevier. - 0003-2670 .- 1873-4324. ; 902, s. 22-32
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Forskningsöversikt (refereegranskat)abstract
- The traceable and accurate measurement of biogas impurities is essential in order to robustly assess compliance with the specifications for biomethane being developed by CEN/TC408. An essential part of any procedure aiming to determinate the content of impurities is the sampling and the transfer of the sample to the laboratory. Key issues are the suitability of the sample container and minimising the losses of impurities during the sampling and analysis process. In this paper, we review the state-of-the-art in biogas sampling with the focus on trace impurities. Most of the vessel suitability studies reviewed focused on raw biogas. Many parameters need to be studied when assessing the suitability of vessels for sampling and storage, among them, permeation through the walls, leaks through the valves or physical leaks, sorption losses and adsorption effects to the vessel walls, chemical reactions and the expected initial concentration level. The majority of these studies looked at siloxanes, for which sampling bags, canisters, impingers and sorbents have been reported to be fit-for-purpose in most cases, albeit with some limitations. We conclude that the optimum method requires a combination of different vessels to cover the wide range of impurities commonly found in biogas, which have a wide range of boiling points, polarities, water solubilities, and reactivities. The effects from all the parts of the sampling line must be considered and precautions must be undertaken to minimize these effects. More practical suitability tests, preferably using traceable reference gas mixtures, are needed to understand the influence of the containers and the sampling line on sample properties and to reduce the uncertainty of the measurement.
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| 5. |
- Balgoma, David, et al.
(författare)
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Modeling the fragmentation patterns of triacylglycerides in mass spectrometry allows the quantification of the regioisomers with a minimal number of standards
- 2019
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Ingår i: Analytica Chimica Acta. - : Elsevier BV. - 0003-2670 .- 1873-4324. ; 1057, s. 60-69
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Tidskriftsartikel (refereegranskat)abstract
- Mass spectrometry allows the relative quantification of the regioisomers of triacylglycerides by the calibration of their fragmentation patterns. However, due to the plethora of regioisomers of triacylglycerides, calibration with every standard is not feasible. An analytical challenge in the field is the prediction of the fragmentation patterns of triacylglycerides to quantify their regioisomers. Thus, we aimed to model these fragmentation patterns to quantify the regioisomeric composition, even for those without commercially available standards. In a first step, we modeled the fragmentation patterns of the regioisomers of triacylglycerides obtained from different published datasets. We found the same qualitative trends of fragmentation beyond differences in the type of adduct in these datasets (both [M+NH4]+ and [M+H]+), and the type of instrument (orbitrap, Q-ToF, ion-trap, single quadrupole, and triple quadrupole). However, the quantitative trends of fragmentation were adduct and instrument specific. From these observations, we modeled quantitatively the common trends of fragmentation of triacylglycerides in every dataset. In a second step, we applied this methodology on a Synapt G2S Q-ToF to quantify the regioisomers of triacylglycerides in sunflower and olive oils. The results of our quantification were in good agreement with previous published quantifications of triacylglycerides, even for regioisomers that were not present in the training dataset. The species with more than two highly unsaturated fatty acids (arachidonic, eicosapentaenoic, and docosahexaenoic acids) showed a complex behavior and lower predictability of their fragmentation patterns. However, this framework presents the capacity to model this behavior when more data are available. It would be also applicable to standardize the quantification of the regioisomers of triacylglycerides in an inter-laboratory ring study.
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| 6. |
- Beech, Jason P., et al.
(författare)
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Separation of pathogenic bacteria by chain length
- 2018
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Ingår i: Analytica Chimica Acta. - : Elsevier BV. - 0003-2670 .- 1873-4324. ; 1000, s. 223-231
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Tidskriftsartikel (refereegranskat)abstract
- Using Deterministic Lateral Displacement devices optimized for sensitivity to particle length, we separate subpopulations of bacteria depending on known properties that affect their capability to cause disease (virulence). For the human bacterial pathogen Streptococcus pneumoniae, bacterial chain length and the presence of a capsule are known virulence factors contributing to its ability to cause severe disease. Separation of cultured pneumococci into subpopulations based on morphological type (single cocci, diplococci and chains) will enable more detailed studies of the role they play in virulence. Moreover, we present separation of mixed populations of almost genetically identical encapsulated and non-encapsulated pneumococcal strains in our device.
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| 7. |
- Cavanillas, Santiago, et al.
(författare)
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A self-polishing platinum ring voltammetric sensor and its application to complex media
- 2015
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Ingår i: Analytica Chimica Acta. - : Elsevier Masson. - 0003-2670 .- 1873-4324. ; 859, s. 29-36
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Tidskriftsartikel (refereegranskat)abstract
- A self-polishing voltammetric sensor was recently developed and has been applied to samples of urea, milk and sewage water. The polishing device continuously grinds a platinum ring electrode, offering a reproducible and clean electrode surface. Principal component analysis (PCA) and partial least squares (PLS) techniques were applied to interpret the data and to build prediction models. In an evaluation of samples with different urea concentrations, the grinding step allows for repeatable measurements, similar to those after electrochemical cleaning. Furthermore, for the determination of sewage water concentrations in drinking water and for the evaluation of different fat contents in milk samples, the polishing eliminates sensor drift produced by electrode fouling. The results show that the application of a self-polishing unit offers a promising tool for electrochemical studies of difficult analytes and complex media. (C) 2014 Elsevier B.V. All rights reserved.
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| 8. |
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| 9. |
- Chen, Chang, et al.
(författare)
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Untargeted screening of unknown xenobiotics and potential toxins in plasma of poisoned patients using high-resolution mass spectrometry: Generation of xenobiotic fingerprint using background subtraction
- 2016
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Ingår i: Analytica Chimica Acta. - : ELSEVIER SCIENCE BV. - 0003-2670 .- 1873-4324. ; 944, s. 37-43
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Tidskriftsartikel (refereegranskat)abstract
- A novel analytical workflow was developed and applied for the detection and identification of unknown xenobiotics in biological samples. High-resolution mass spectrometry (HRMS)-based data-independent MSE acquisition was employed to record full scan MS and fragment spectral datasets of test and control samples. Then, an untargeted data-mining technique, background subtraction, was utilized to find xenobiotics present only in test samples. Structural elucidation of the detected xenobiotics was accomplished by database search, spectral interpretation, and/or comparison with reference standards. Application of the workflow to analysis of unknown xenobiotics in plasma samples collected from four poisoned patients led to generation of xenobiotic profiles, which were regarded as xenobiotic fingerprints of the individual samples. Among 19 xenobiotics detected, 11 xenobiotics existed in a majority of the patients plasma samples, thus were considered as potential toxins. The follow-up database search led to the tentative identification of azithromycin (X5), alpha-chaconine (X9) and penfluridol (X12). The identity of X12 was further confirmed with its reference standard. In addition, one xenobiotic component (Y5) was tentatively identified as a penfluridol metabolite. The remaining unidentified xenobiotics listed in the xenobiotic fingerprints can be further characterized or identified in retrospective analyses after their spectral data and/or reference compounds are available. This HRMS-based workflow may have broad applications in the detection and identification of unknown xenobiotics in individual biological samples, such as forensic and toxicological analysis and sport enhancement drug screening. (C) 2016 Elsevier B.V. All rights reserved.
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| 10. |
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