Extraction of sulfonamides from honey using admicelle solid phase extraction sorbent prior to liquid chromatographic determination

A new solid phase extraction method for four sulfonamides as sulfadiazine, sulfamethazine, sulfamerazine and sulfamethoxazole in honey was developed. Fortified honey samples were studied in order to check the accuracy of this method. The sorbent used in the solid phase extraction method was prepared by modifying silica at pH 9 with surfactant such as cetlytrimethyl ammonium bromide. The FTIR and SEM analysis of the prepared sorbent were performed. The proposed method was optimized in terms of some parameters; pH of sample solution, amount of surfactant, eluent type and volume, flow rate using test solutions containing sulfonamides at a concentration of 0.5 mg per L. The optimized values are; pH 6, 50 mg of surfactant, 4 mL of methanol: water with ratio of 1:1 as desorption solvent mixture and 1.5 mL per min for flow rate of loading of sample. The analysis of sulfonamides were carried out on HPLC-DAD using mobile phase as methanol: acetonitrile: 0.05 M formic acid with ratio of 10:15:75. Chromatographic separation was obtained by isocratic elution. The sulfonamides were detected at 272 nm. The detection limit of the HPLC method was in the range of 3-13 ng per mL for all analytes. The linear ranges of sulfonamides were from 0.010 to 2.000 mg per L. The precision of this method as relative standard deviation percentage, RSD percentage, at 0.1 mg per L was found less than 5.91 percentage for all analytes for 5 replications. The amounts of sulfonamides in honey samples by this method were found in the range of 0 to 1.30 ppm. The recovery as percentage of this method using fortified honey samples were above mostly 70 percentage for all studied sulfonamides. Keywords: Sulfonamides, honey, solid phase extraction, HPLC.