Determination of levamisole in animal tissues using liquid chromatography with ultraviolet detection

An efficient and sensitive liquid chromatographic method is described for the determination of the anthelminthic drug levamisole, in muscle, liver, kidney and fat of sheep, pigs and poultry, using thiabendazole as internal standard. Samples were extracted by homogenizing with chloroform, and were applied to Supelco Si solid-phase extraction columns and eluted with methanol. Chromatographic analysis was performed on a LiChrospher 60 RP-Select B column using methanol/ammonium acetate buffer 0.05 M (55/65, v/v) as mobile phase and reading at 220 nm. The quantification limit for the assay was 4 ng/g. Mean recoveries were about 84% for liver, 85% for kidney, 89% for muscle and 84% for fat. The assay has been used for statutory testing purposes.