Simultaneous Determination by GC-MS-SIM of o-, m-, p-Hydroxyphenylacetic Acid, 3:4-Dihydroxyphenylacetic Acid and Homovanillic Acid in Biological Samples Using a Common Selected Ion

Abstract

A GC-MS-SIM method is described for the simultaneous determination of five acid metabolites, o-, m-, and p-hydroxyphenylacetic acid,3:4-dihydroxyphenylacetic acid and homovanillic acid in biological samples using a common selected ion for all the acids. The TMS ethers of methyl or ethyl esters of these compounds have a common ion at m/e 179 which is used for their quantitation by selected ion monitoring. The molecular ion at m/e 238 of the three monohydroxy phenylacetic acids, which is also the M-30 ion for homovanillic acid, is also used for their quantitation. The GC conditions for their separation, the relative sensitivities and some advantages of TMS ethers over other derivatives are described. The application of this method to biological samples is illustrated by data on human urine and plasma.