Emulsification Based Liquid Microextraction Prior to Flame Atomic Absorption Spectrometry for Sensitive Determination of Copper in Water Samples

Abstract

In this study emulsification based liquid microextraction (EBLME) was developed for preconcentration of Cu(II) using a redesigned dispersive liquid - liquid microextraction (DLLME). The procedure is based on an organic extraction solvent and aqueous solution of surfactant system where a mixture contains appropriate amounts of the extraction solvent (25.6 µg mL-1 dithizone chloroformic solution) and aqueous solution of sodium dodecyl sulfate (SDS) as a disperser. Immediately after the injection, a cloudy media is formed containing oil in water microemulsions; into which the analyte ions could be extracted. After centrifugation, the copper is determined in the enriched phase by flame atomic absorption spectrometer. Some factors influencing the extraction efficiency of copper ion determination were studied and optimized. Under the optimized conditions, the relative standard deviation (RSD) for seven repeated determinations, at a concentration of 0.2 µg mL-1 was obtained to be 3.9 %. The limit of detection and enrichment factor were 0.32 ng mL-1 (S/N = 3) and 147, respectively. A comparison between the employed method and dispersive liquid–liquid microextraction indicates that emulsification based liquid microextraction (EBLME) has simplicity, rapidity, reproducibility, and possesses lower limit of detection and higher enrichment factor for determination of copper ion in natural waters. Keywords: Emulsification based liquid microextraction, Copper, Water analysis, flame atomic absorption spectrometry, Surfactant, Preconcentration.