Quantitation of blood and plasma amino acids using isotope dilution electron impact gas chromatography/mass spectrometry with U-(13)C amino acids as internal standards.

A method to quantitate blood and plasma amino acids by isotope dilution gas chromatography/mass spectrometry (GC/mS) is described. Samples were spiked with U-(13)C amino acids as internal standards and the tert-butyldimethylsilyl derivatives (tBDMS) separated by capillary column gas chromatography. Linear regression curves, generated for individual amino acids, gave correlation coefficients of 0.9999. The reproducibility of the method was assessed from the analysis of 10 replicate blood and plasma samples. For most amino acids a coefficient of variance (CV) of