Determination of 17-β-Estradiol in Water Samples Using Salting-out Assisted Liquid-liquid Extraction Followed by HPLC and Experimental Design for Optimization

The aim of the present study was to extract, preconcentrate, and determine 17-β-estradiol in water samples using a simple and efficient method. To this end, salting-out-assisted liquid-liquid extraction and high-performance liquid chromatography with ultra violet detection at 210 nm were performed. Water-miscible acetonitrile, as the extractant and acetonitrile phase separation under high-salt conditions were applied to treat the samples. The extraction efficiency and method sensitivity were carefully monitored by controlling the effective factors and the optimum conditions were: sodium chloride as the salting-out agent at concentration of 1.6 g, 2.40 ml of acetonitrile as extraction solvent, 5 ml of water sample, vortexing for 2 min and centrifuging at 4000 rpm for 5 min. A central composite design was applied to optimize the hydrolysis parameters. Using optimized experimental conditions, the calibration curve was found to be linear in the range of 1-120 μg l-1 in water sample and the correlation coefficient (R2), the limit of detection, and limit of quantification were >0.99, 0.25 μg ml-1, and 0.83 μg l-1, respectively. The enrichment factor and extraction recoveries of the selected analyte ranged from 44.96-49.57 and 89.93-99.15%, respectively. Relative standard deviations were about 5.94%. High extraction efficiency and compatibility with HPLC analysis of 17-β-estradiol in water samples are the advantages of this method.