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Geis-Asteggiante L Lehotay SJ Fortis LL Paoli G Wijey C Heinzen H 《Analytical and bioanalytical chemistry》2011,401(8):2617-2630
Microcystins (MCs) are the most common cyanotoxins found worldwide in freshwater, brackish, and marine environments. The rapid
and accurate analysis of MCs and nodularin (Nod-R) in fish tissue is important for determining occurrence, following trends,
and monitoring exposure for risk assessment and other purposes. The aim of this study was to develop a streamlined and reliable
sample preparation method for eight MCs (MC-RR, MC-YR, MC-LR, MC-WR, MC-LA, MC-LY, MC-LW, and MC-LF) and Nod-R in fish, and
conduct a validation of the new method using liquid chromatography–tandem mass spectrometry (LC-MS/MS) for analysis and compare
the results with a commercial enzyme-linked immunosorbent assay (ELISA) kit. Different sample preparation methods were compared,
and a simple extraction protocol with acidified acetonitrile/water (3:1) followed by hexane partitioning cleanup was found
to be most effective. Thorough validation of the final method was conducted, and 90–115% recoveries were achieved for all
analytes except for MC-RR, which gave 130% average recovery (isotopically labeled internal standards were unavailable to correct
for possible biases). The use of electrospray ionization in the negative mode gave few interferences and minimal matrix effects
in the LC-MS/MS analysis overall. Precision was typically 10–20% RSD among multiple days in experiments, detection limits
were <10 ng/g in the fish tissue (catfish, basa, and swai filets), and no false-positives or false-negatives occurred in blind
analyses of many spiked samples. The ELISA was unable to distinguish between MCs but was found to correctly assess the presence
or absence of MCs and Nod-R in the blind-fortified fish tissues. The capability of these approaches to measure covalently
bound MCs was not assessed. 相似文献
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A discussion is given of the relation between the maximum functionaltheorem and Schwinger's variational principle, and it is shownthat the bound given by Schwinger's principle is better thanor the same as that given by the maximum functional theorem. 相似文献
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Guerrier L Claverol S Finzi L Paye F Fortis F Boschetti E Housset C 《Journal of chromatography. A》2007,1176(1-2):192-205
Proteins in bile may have important physiological functions and serve as disease biomarkers. Here, the protein composition of human gallbladder bile was analyzed using a recently described chromatography-like technology capable to enhance the signal of low-abundance species. First, proteins present in bile fluid were treated with immobilized peptide ligand libraries to concentrate dilute and very dilute species while concomitantly diluting the high-abundance proteins. The analysis of resulting protein mixture was then performed using LC-MS/MS after having classically separated proteins by a mini preparative gel electrophoresis. Overall 222 gene products were found; 143 of them were not reported before in proteomics studies. Ligand libraries by themselves contributed to find 81 new gene products distributed throughout different categories. The described chromatographic approach provides a significant contribution to the bile protein repertoire and opens new perspectives for the discovery of markers for specific biliary tract diseases. 相似文献
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Van Zandt LL 《Physical review letters》1986,57(16):2085-2087
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Following the variational principles for linear initial valueproblems associated with the wave and heat conduction equationsdiscussed by Gurtin and Leitmann and using time convolutionsit is shown that general variational principles exist for theseproblems with sources on the boundaries and within the regionunder consideration. 相似文献
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Modified Locally One Dimensional Methods for Parabolic Partial Differential Equations in Two Space Variables 总被引:1,自引:0,他引:1
In this note we consider the locally one dimensional methodas discussed in Gourlay & Mitchell (1969, 1972) and indicatehow this scheme can be used to solve accurately a parabolicpartial differential equation in two space variables. 相似文献
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