DETERMINATION OF CARBADOX AND ITS METABOL ITE, QUINOXALINE-2-CARBOXYLIC ACID, IN SWINE TISSUES BY HPLC

A simple and rapid method for the simultaneous determination of carbad ox (CDX) and quinoxaline-2-carboxylic acid (QCA), the most persistent metabolite, in swine tissues has been developed by HPLC with photodiod e array detection. The drugs were extracted with 0.3% metaphosphoric a cid-MeOH (7 : 3, v/v), and the extracts were cleaned up with a Bond El ut C-18 cartridge. The HPLC separation was performed on a Wakosil-II 5 C18 RS column (150 x 4.6 mm i.d.) with a gradient system of 0.01 M pho sphate buffer (pH 2.5)-MeCN as the mobile phase, at the flow-rate of 0 .6 ml/min. The calibration graphs were rectilinear from 0.5 to 50 ng f or CDX and QCA. The recoveries of CDX and QCA from swine muscle and li ver fortified at the level of 0.1 mu g/g were 85.0 similar to 94.3%, w ith high precision. The limits of detection were 0.005 similar to 0.01 mu g/g for CDX and QCA. Further, a preliminary investigation was carr ied out in order to determine the toxic metabolite desoxy-carbadox.