Determination of total homocysteine in human serum by capillary gas chromatography with sulfur-specific detection by double focusing ICP-MS.

Abstract

A selective and sensitive method for determination of total homocysteine (Hcy) in human serum, by gas chromatography coupled to ICP-MS(HR), has been developed. After reduction of the sample with sodium borohydride the liberated Hcy and other aminothiols, such as cysteine (Cys) and methionine (Met), were converted to their N-trifluoroacetyl (TFA)- O-isopropyl derivatives and these were injected into a gas chromatograph equipped with an HP-5 capillary column. Detection was carried out by means of a double-focusing inductively coupled plasma mass spectrometer (DF-ICP-MS) monitoring (32)S at m/Delta m (resolving power)=3000. The transfer line used to transport the analytes from the GC column to the ICP-MS had previously been developed in our laboratory. The different parameters affecting the derivatisation process were optimised, as were the instrumental operating conditions. This optimised GC-ICP-MS(HR) method was successfully applied to the determination of total homocysteine in human serum-values obtained were in agreement with data reported in the literature. Quantitative recoveries and good precision were obtained for spiked human serum, demonstrating the suitability of the method for quantitative determination of total homocysteine in serum.