Ultrasound‐Assisted Emulsification‐Microextraction With In Situ Derivatization and Gas Chromatography‐Electron‐Capture Detection for Determination of Chlorophenols in Water

Abstract

A new method, ultrasound‐assisted emulsification–microextraction (USAEME) with in situ derivatization and gas chromatography‐electron‐capture (GC‐μ‐ECD) detection, was developed to determine selected chlorophenols (CPs), including 2‐chlorophenol, 2,6‐dichlorophenol, 2,4,5‐trichlorophenol, 2,3,4,6‐tetrachlorophenol, and pentachlorophenol in water and wastewater samples. Initially the suitable solvent was determined and amount of derivatization reagent (acetic anhydride) and K2CO3, other experimental variables involving extraction and derivatization time, volume of extraction solvent and sample ionic strength, were optimized employing a 23 factorial experimental design. The developed method employed 100 μL of chloroform as extraction solvent, extraction with in situ derivatization for 10 min using 100 µL of acetic anhydride and 100 µL K2CO3 (5%, w/v) for 5 mL samples at 25°C with no ionic strength adjustment and centrifugation for 5 min at 4000 rpm. The average relative recoveries under optimum conditions were >97% with relative standard deviation (RSD) ≤5% for three different spiking levels (5, 20, and 100 μg L‐1). The limits of detection for studied CPs were in the range of 0.007–0.011 μg L−1. The developed USAEME with in situ derivatization method was successfully applied to real water samples such as tap, dam water, and domestic wastewater. The developed method showed comparable efficiency with conventional liquid–liquid extraction‐derivatization coupled with GC‐μ‐ECD. The results demonstrated that the developed USAEME with in situ derivatization is simple, fast and reliable for determination of selected CPs in water samples by GC‐μ‐ECD.