Determination of sulfonamides in blood using acetonitrile–salt aqueous two-phase extraction coupled with high-performance liquid chromatography and liquid chromatography–tandem mass spectrometry
An acetonitrile–salt aqueous two-phase extraction system (ATPS) was developed and applied in the extraction of sulfonamides in blood. HPLC and HPLC–MS were applied in the determination of the analytes. 3 mL of blood sample was diluted with 1 mL pure water and 6 mL of acetonitrile and 1 g of K2HPO4 were added to the sample. The mixture was ultrasonically shaken for 5 min. The ATPS was formed. The hemoglobin in blood was gathered together and suspended between the acetonitrile and aqueous phases. The parameters affecting the extraction efficiency, such as type and volume of extraction solvent, type and amount of salt, pH value of sample solution, extraction time and the amount of dissolution solvent were investigated. The limits of detection for sulfamonomethoxine, sulfachlorpyridazine, sulfamethoxazole and sulfafurazole were 4.81, 1.87, 2.73, 2.17 μg L−1, respectively. When the present method was applied in the analysis of blood samples, the recoveries of the analytes ranged from 80.1 to 96.9% and the relative standard deviations were lower than 7.13%.