HPLC determination of sulfadimethoxine and its hydroxy metabolites following SPE of edible chicken tissues

New cleanup techniques by an anion-exchange SPE column and a centrifugal ultra-filtration unit and a high performance liquid chromatographic (HPLC) determination of residual sulfadimethoxine (SDM) and its hydroxy metabolites (OH-SDMs), 4-sulfanilamido-6-methyl-2-hydroxy-4-pyrimidine (2-OH-SDM), 4-sulfanilamido-2-methyl-6-hydroxy-4-pyrimidine (6-OH-SDM), and 4-sulfanilamido-2,6-dihydroxy-4-pyrimidine (2,6-diOH-SDM), in edible chicken tissues (liver and muscle) were presented. The sample preparation was performed by homogenizing with a mixture of 90% (v/v) acetonitrile solution and n-hexane (5:4, v/v) to minimize the fat amount followed by ISOLUTE(R) SAX column and Ultrafree(TM) C3 as a centrifugal ultra-filtration unit. A Mightysil(R) RP-4 GP column and an isocratic mobile phase of 4% (v/v) acetic acid solution - acetonitrile - N,N-dimethylformamide (83:12:5, v/v/v) with a photo-diode array detector was used. Average recoveries of spiked SDM and OH-SDMs (0.1 and 0.5 ppm), respectively, were > 80.1% with coefficients of variation between 0.5 and 4.8%. The practical limit of detection was 0.05 ppm for all compounds.