SIMULTANEOUS ASSAY FOR ISONIAZID AND HYDRAZINE METABOLITE IN PLASMA AND CEREBROSPINAL-FLUID IN THE RABBIT

A simple procedure for the simultaneous determination of isoniazid and hydrazine metabolite in plasma and cerebrospinal fluid in the rabbit is described. The assay involves organic extraction before and after derivatization of the two compounds and the internal standard, phenelzine. The extract of the derivatized compounds was evaporated to dryness at 40-degrees-C and the residue redissolved in the mobile phase (50-mu-l). A 25-mu-l aliquot was injected into the liquid chromatograph and eluted with acetonitrile-water-triethylamine (70:30:0.4, v/v) containing 5 mM heptanesulphonic acid on a 30-mu-m C8 precolumn linked to a 10-mu-m C18-mu-Bondapak column at ambient temperature (25 +/- 1-degrees-C). The eluate was detected by ultraviolet detection at 320 nm.