An efficient and cost-effective method was developed for the simultaneous determination of the residues of diclazuril and toltrazuril in in chicken tissues matrix solid-phase dispersion ( MSPD) and high-performance liquid chromatography ( HPLC) - ultraviolet detection ( UVD). The optimal manipulation of MSPD was performed: 0. 5 g of homogenate of chicken tissue consisting of the premixed standard solution of diclazuril and toltrazuril was blended with 2 g of C, bulking agent in a clear-glass mortar. The blended material was transferred to a 10-mL column extractor after standing at ventilated chamber for 2 - 5 min. The column extractor was fill with glass cotton, 1. 5 g of anhydrous sodium sulfate, the blended material, and 0. 5 g of anhydrous sodium sulfate in sequential order from underlayer to upper layer. And then, the column extractor with previous material was eluted with 8 ml each of three solvents ( N-hexane, methanol/water( 1: 4, V/V), and methanol) in sequential order. All fractions were then evaporated to dryness under nitrogen gas at 50 degrees C. Once dried, samples were dissolved in 0. 5 mL of 0. 05 mol/L phosphate acid/triethylamine buffer-acetonitrile (40:60). After the sample solution was filtrated with filter membrane(0. 22 mu m), 20 mu L of the sample solution were injected into the HPLC system. Under the optimal chromatographic condition, the diclazuril and toltrazuril were separated on C column (250 mm x 4. 6 mm i. d. 5 mu m) with 0. 05 mol/L phosphate acid/triethylamine buffer-acetonitrile (40:60) as the mobile phase, and flow rate of 1. 0 mL/min, then were detected by ultraviolet detector at 240 nm wavelength with 0. 05 of AUFS, the injection volume 20 mu L and the column temperature was maintained at 25 degrees C. The linear range for quantitative analysis was between 50 and 1000 ng/g. At the added levels of 50, 500, 1000 ng/g, the recoveries of diclazuril and toltrazuril from chicken tissu ranged from 71. 13% - 84. 02% with the relative standard deviations ( RSD) in the range of 3. 76% - 12. 11 %, and the RSDs of intra-and inter-day analyses ranged from 3. 70% - 6. 77 %. The detection limits of diclazuril and toltrazuril were 8 and 7 ng/g for muscle respectively, and 10 ng/g for liver and kidney. The quantitation limits of of diclazuril and toltrazuril were 10 and 12 ng/g for muscle respectively, and 15 ng/g for liver and kidney.
