DERIVATIZATION HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHIC DETERMINATION OF METHANOL IN HUMAN PLASMA

A simple and sensitive high performance liquid chromatographic method is described for the determination of methanol in human plasma, as a h ighly sensitive derivative. The methanol, spiked in plasma, after simp le ultrafiltration treatment, was derivatized with 3-bromomethyl-7-met hoxy-1,4-benzoxazin-2-one in a heterogeneous system, using benzalkoniu m chloride as phase transfer catalyst. The resulting derivative was ch romatographed on a LiChrospher diol column with n-hexane:dichlorometha ne (9:1, v/v) as the mobile phase and 1-nitronaphthalene as the intern al standard. The HPLC system showed good selectivity for methanol dete rmination. Several parameters affecting the derivatization of methanol extracted from spiked plasma were investigated. The linear range for the determination of methanol in spiked human plasma was over 1-10 mu mol/mL; the detection limit (signal to noise = 5, sample size 10 mu L) of methanol was about 0.06 +/- 0.02 mu mol/mL. The intraday relative standard deviation (n = 6) and the interday relative standard deviatio n (n = 8) were all below 5%. Recovery of methanol in spiked human plas ma was greater than 98%.