In-Syringe Dispersive Liquid-Liquid Microextraction Coupled with High- Performance Liquid Chromatography for Trace Analysis of Naphthalene Sulfonates in Seawater

Background: A rapid methodology has been developed and applied successfully for the determination of trace levels of four naphthalene sulfonate (NSs) in seawater. Objective: The aim of this research was finding a rapid, interference-free and easy to operate extraction technique for isolation and preconcentration of NSs from seawater. Method: This technique is based on coupling of in-syringe dispersive liquid-liquid microextraction to high-performance liquid chromatography. Naphthalene sulfonate (NSs) forms ion-pair species with tetrabutylammonium (TBA) and then were microextracted to an organic phase by IS-DLLME followed with high-performance liquid chromatography (HPLC) analysis. The effects of different parameters on the extraction efficiency such as pH, type and volume of extraction solvent, the type and volume of dispersive solvent, the effects of multiple extractions, sample volume, and amount of tetrabutylammonium (ion pair in reagent) were studied and optimized. Results: The effects of different parameters on the extraction efficiency such as pH, type and volume of extraction solvent, the type and volume of dispersive solvent, the effects of multiple extractions, sample volume, and amount of tetrabutylammonium (ion pair in reagent) were studied and optimized. Under the optimized condition, the linear ranges were found to be between 0.1-100.0 μg L-1 for all NSs with the detection limits better that 0.32 μg L-1. The enrichment factors of NSs were calculated to be between 172 and 280 folds. The mean recoveries of NSs were 80.2-104.5 % with mean RSD of 2.6-6.6 %. Conclusion: The technique has been successfully applied for the analysis of trace amount of four naphthalene sulfonates in seawater of Chabahar Bay.