Determination of total homocysteine in blood plasma by capillary electrophoresis with mass spectrometry detection

The advantages and potencies of direct methods for the quantification of homocysteine based on mass spectrometry detection (HPLC-MS and CE-MS) are considered; these significantly simplify sample preparation and exclude derivatization with expensive derivatizing reagents. An approach is developed for the direct determination of total homocysteine in blood plasma in an analytical system that combines capillary electrophoresis with electrospray ionization. The internal standard is glycyl-asparagine; the duration of separation is 25 min. The sample is preconcentrated tenfold prior to the determination. The sample pretreatment also includes the precipitation of proteins with methanol and the reduction of amino thiols with dithiothreitol or mercaptoethanol. The recovery values make 87–112%.