Separation and determination of anionic surfactants by polymeric nanofibers as a micro-solid phase extraction and optimization of extraction conditions using response surface methodology

Anionic surfactants are currently the types most used, being incorporated in the majority of detergent and cleaning-product formulas in daily use [1]. But these kind of compounds cause water pollution of water supply source, such as rivers and lakes, and attract as one of the factors which affect naural ecosystem then determination of their concentration is important [2]. In this study we use polymeric nano-fibers prepared by the electrospinning method as a micro-solid phase extraction (μ-SPE) for extraction, purification and preconcentration of Sodium dodecyl sulfate (as a sample of anionic surfactants). Characteristics of the fibers were inspected by Energy dispersive spectroscopy (EDAX), scanning electron microscopy (SEM), and Fourier-transform infrared spectroscopy (FT-IR).The amount of anionic surfactants was measured by UV-Vis spectroscopy using Methylene Blue based on the formation of the ionic pair anionic surfactant-methylene blue and the extraction of the ion pairs and measuring the absorbance at 654 nm.The effective factors on extraction were optimized by response surface methodology (RSM). The optimum conditions included pH 9, 0.5 mL for elution solvent volume and 0.0636 grams of sorbent.Under the optimized conditions, the method showed linearity with correlation coefficient of 0.995. Also Relative standard deviation was calculated 0.66%.Furthermore, the proposed method was successfully applied to the quantification of residual anionic surfactants in the surfaces of dishes washed with dishwasher and hand wash.