Determination of alliin in rat plasma by liquid chromatography-electrospray ionization mass spectrometry

A rapid and sensitive high performance liquid chromatography-electrospray/MS method has been developed to determine alliin in rat plasma. The method involved deproteinization of these samples with 2.5-volumes (v/w) of acetonitrile/ethanol (1:1) and then 5 mu L aliquots of the supernatant were injected onto a amino-silica (NH2) column coupled with an electrospray/MS system. The mobile phase employed isocratic elution with 5% acetonitrile for 10 min; the flow rate was 1.0 mL/min. The column effluent was analyzed by selected ion monitoring (SIM) for the negative pseudo-molecular ion of alliin [M-H](-) at m/z 176. The limit of detection for alliin in rat plasma by this method was ca. 10 ng/mL and the accuracy for intra- and inter-assay were between 88.3% and 110.1%. The coefficients of variation of the intra- and inter-assay were generally low (below 9.2% and 11.0%, respectively) for rat plasma. No problems were encounted due to interference from endogenous substances.