A Multiresidue Method for the Isolation and Liquid Chromatographic Determination of Seven Sulfonamides in Infant Formula

Abstract

A multiresidue method for the isolation and high performance liquid chromatographic (photodiode array, UV 270nm) determination of sulfathiazole, sulfisoxazole, sulfamerazine, sulfamethazine, sulfamethoxazole, sulfisoxazole and sulfadimethoxine in a milk-based infant formula is presented. Blank or sulfonamide spiked infant formula samples were blended with octadecylsilyl derivatized silica (C-18) packing material. A column made from the C-18/infant formula matrix was first washed with hexane following which the sulfonamides were eluted with methylene chloride. The eluate contained sulfonamide analates which were free from interfering compounds when analyzed by liquid chromatography. This resulted in correlation coefficients (0.9973 ± 0.0016 to 0.9992 ± 0.0006), recovery percentages (75.91 ± 11.12% to 112.01 ± 8.15%) and inter- (5.51 ± 1.74% to 15.27 ± 8.14%) and intra-assay (1.71 to 8.89%) variabilities for individual sulfonamides, over the concentration range (62.5 to 2000 ng/mL) examined, that are indicative of a useful method for the rnultiresidue analysis of milk-based infant formula for the presence of sulfonamides.