High performance liquid chromatographic determination of methapyrilene hydrochloride in feed and sleep aid tablets

Methapyrilene hydrochloride (MP-HCl) was extracted from feed with methanol and determined by reverse phase partition chromatography in less than 15 min, using isocratic elution with acetonitrile-1.1% ammonium carbonate (1 + 1) as the mobile phase. This procedure was tested on feed treated with MP-HCl at levels of 125, 500, and 2000 ppm. Recoveries were 104, 95, and 96% with coefficients of variation of 2.4, 1.6, and 0.6%, respectively. MP-HCl in feed was stable for 14 days. This method was also successfully used to determine MP-HCl in 3 sleep aid tablets.