On-line solid phase extraction coupled with sequential injection system for determination of sulfonamides

Abstract

In this work, sequential-injection on-line solid-phase extraction (SPE) coupled with high-performance liquid chromatography (HPLC) for the separation and determination of sulfonamides (SAs) has been developed. A homemade microcolumn SPE was automated by sequential-injection analysis to perform on-line sample clean-up and extraction. A sequential-injection analysis (SIA) system consisting of a syringe pump and multi-position valve was constructed. This method can continuously extract sulfonamides from aqueous samples followed by the separation of sulfonamides using HPLC coupled with boron-doped diamond (BDD) electrode as electrochemical detection. The conditions for on-line SPE including eluent, flow rate of sample loading and elution, and zone of eluate were investigated. An eluent composition of methanol was selected. The optimal flow rate of sample loading and elution was found to be 10 µL/s and optimal elution time was 20-24 s. Under optimal conditions, a linear relationship between peak height and sulfonamides concentration was obtained in the range of 0.01-8 ppm. The results demonstrate that this method is simple, rapid and highly sensitive for the automated extraction, separation, and determination of sulfonamides.