Quantitation of levamisole in plasma using high performance liquid chromatography.

A rapid and sensitive procedure is described for the quantitation of levamisole in plasma using high-performance liquid chromatography (HPLC). The procedure involves sample preparation using a reverse-phase C18 cartridge prior to chromatography and quantitation using peak area ratios (UV absorbance detection, 225 nm) of levamisole to the internal standard, quinine. The limit of detection was 21 ng/ml and the limit of quantification was 72 ng/ml, both contained in 1 ml of plasma. The recoveries were sufficiently high (73.1%) and overall coefficient of variation of the procedure was 0.25%. This procedure has been used to determine levamisole levels in human and cattle plasma. A comparison of using two C18 columns (Nova-pak, Puresil) was also studied and discussed.