Determination of citalopram, amitriptyline and clomipramine in plasma by reversed-phase high-performance liquid chromatography

The determination of citalopram, amitriptyline, clomipramine and their desmethyl metabolites after alkaline diethyl either extraction from plasma is achieved by high-performance liquid chromatography using two internal standards and mu Bondapak C18 as stationary phase. Elution is carried out isocratically at 0.5 or 1 ml/min with a mixture of acetonitrile-potassium dihydrogen phosphate-distilled water (45:50:5). Detection is monitored by absorption at 254 nm. The detection limit is less than 5 ng/ml for each compound. The coefficients of variation are between 1.3% and 9.4% for 8-360 ng/ml. Interference from 22 possible co-medications is discussed. The technique can be used for therapeutic monitoring of these antidepressants as well as in analytical toxicology.