LC determination of moclobemide and three metabolites in plasma.

Moclobemide and three metabolites were quantified using 1 ml of plasma and solid-phase extraction with Bakerbond CN column after the addition of nadolol as the internal standard (I.S.). Separation and detection the analysed substances were achieved isocratically with acetonitrile-methanol-0.067 M phosphate buffer pH 2.65-0.4% triethylamine (12.7:1.9:85:0.4, v/v/v/v), a Nova-pak C(8) column and UV detection at 230 nm. The lower limits of quantitation for moclobemide was 10 ng ml(-1), for M1 (Ro 16-3177)-8 ng ml(-1), for M2 (Ro 12-5637)-10 ng ml(-1) and for M3 (Ro 12-8095)-15 ng ml(-1) (as the metabolites). Accuracies calculated of three concentrations in each of three separate runs were between 84.55 and 93.68 for moclobemide, 83.28 and 92.30 for M1, 86.31 and 92.66 for M2 and 88.42 and 93.40 for M3. Precision data within day were between 5.71 and 7.50 for moclobemide, 2.91 and 6.58 for M1, 4.98 and 6.40 for M2 and 0.94 and 4.73 for M3.