Liquid chromatography tandem mass protein quantitation

Macek et al. [120] developed a method to quantitate omeprazole in human plasma using liquid chromatography-tandem mass spectrometry. The method is based on the protein precipitation with acetonitrile and a reversed-phase liquid chromatography performed on an octadecylsilica column (55 x 2 mm, 3 /im). The mobile phase consisted of methanol-10 mM ammonium acetate (60 40). Omeprazole and the internal standard, flunitra-zepam, elute at 0.80 0.1 min with a total rim time 1.35 min. Quantification was through positive-ion made and selected reaction monitoring mode at m/z 346.1 —> 197.9 for omeprazole and m/z 314 —> 268 for flunitrazepam, respectively. The lower limit of quantification was 1.2 ng/ml using 0.25 ml of plasma and linearity was observed from 1.2 to 1200 ng/ml. The method was applied to the analysis of samples from a pharmacokinetic study. 

SS. Murphy, A.T Berna, M.J. Holsapple, J.L. Ackermann, B.L. Effects of Flow Rate on High-Throughput Quantitative Analysis of Protein-Precipitated Plasma Using Liquid Chromatography/Tandem Mass Spectrometry, Rapid Commun. Mass Spectrom. 16, 537-543 (2002). 

Li F, Schmerberg CM, Ji QC. Accelerated tryptic digestion of proteins in plasma for absolute quantitation using a protein internal standard by liquid chromatography/ tandem mass spectrometry. Rapid Commun Mass Spectrom 2009 23(5) 729—732. 

Bondarenko, P. V. Chelius, D. Shaler, T. A. Identification and relative quantitation of protein mixtures by enzymatic digestion followed by capillary reversed-phase liquid chromatography-tandem mass spectrometry. Anal. Chem. 2002, 74, 4741 749. 

Locati D, Morandi S, Zanotti M, Arnold A (2006). Preliminary approaches for the development of a high-performance liquid chromatography/electrospray ionization tandem mass spectrometry method for the detection and label-free semi-quantitation of the main storage proteins of Lupinus albus in foods. Rapid Commun. Mass Spectrom., 20 1305-1316. 

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