RESUMO
The applicability of gel permeation chromatography (GPC) to the purification in foodstuffs in the detection of three classes of drugs, sulfonamides, nitrofurans, and growth promoters, is described. This technique has already found a wide application in the routine analysis of pesticides in milk, eggs and grease but to our knowledge there is no published work on the use of GPC for purifying animal feedstuffs for the detection of the above-mentioned classes of drugs. Three main advantages characterize this method: the simultaneous determination of a wide spectrum of drugs; good performance of the purification system; and high recoveries. The method was tested for a determination limit of 1 ppm in each compound. Average recoveries of spiked samples were: 99% for sulfonamides; 98% for nitrofurans; and 100% for carbadox [methyl-3-(2-quinoxalinylmethylene) carbazate-1,4-dioxide] and olaquindox [N-(2-hydroxyethyl)-3-methyl-2-quinoxalinecarboxamide-1,4-dioxide] . The method was also tested for linearity over the range 1-100 ppm and gave r values between 0.9998 and 0.9999 for each drug. Analyses were performed by HPLC, either using a diode array or windowplot-system detector. The described method is quick and simple, which is very useful in routine analysis.