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A simple and rapid method for the simultaneous determination of 35 non-derivatized metabolites was developed using liquid chromatography – tandem mass spectrometry. Under the optimal conditions, linearity was achieved in the range from 0.05 to 10.0 ng (R2 ≥ 0.989). The repeatability provided percentage relative standard deviations ≤11.2 and a trueness expressed as percentage relative error from −10.7% to 12%. The recoveries ranged from 87.3% to 109.8% with good repeatability. When applied to mouse lung tissue, plasma, and urine samples, 30 amino acids, creatine, creatinine, and oxidized glutathione were positively identified and quantified. The described present method was useful for the simultaneous determination of amino acids, creatine, creatinine, and oxidized glutathione in biological samples, including tissue, plasma, and urine. [ABSTRACT FROM AUTHOR]

An efficient method for the simultaneous profiling analysis of 44 fatty acids including 24 aliphatic, 12 hydroxyl, and eight methyl-branched fatty acids astert-butyldimethylsilyl (TBDMS) derivatives was developed by gas chromatography–mass spectrometry. In this study, new mass spectral databases of isolauric, 11-methyllauric, isomyristic, isopentadecylic, isopalmitic, isostearic, 17-methylstearic, and 19-methylarachidic acids were constructed as TBDMS derivatives. Under the optimal conditions, linearity in the range of 0.1–10.0 µg/mL (24 aliphatic fatty acids) and 0.01–1.0 µg/mL (eight methyl-branched and 12 hydroxy fatty acids) showed good correlation coefficients (r ≥ 0.997). The repeatability showed relative standard deviation of less than 11.2% and accuracy (percent relative error) varied from −11.0 to 7.8 for the 44 fatty acids studied. The recoveries ranged from 61.7 to 90.1% with good repeatability. When applied to human plasma sample, 18 aliphatic, three 2-hydroxy, three 3-hydroxy, and five methyl-branched fatty acids were positively identified and quantified. Therefore, the present method will be useful for profiling analysis of various fatty acids in biological samples including plasma. [ABSTRACT FROM AUTHOR]