Recently, cloud-point-extraction (CPE-) based methods method have been extensively used to facilitate preconcentration and separation of the analyte from complex matrices [13]. Separation and preconcentration of the analyte can be easily achieved by using surfactant in place of organic solvent [13]. The presence of surfactant not only facilitates extraction of analyte efficiently but also enhances the sensitivity of the method [14]. Hence, surfactant-mediated extraction procedures provide very good efficiency in extracting the analyte from a large volume of aqueous solution. This protocol is simple, highly efficient, and less expensive and restricts the use of toxic organic solvents. The present paper describes a simple cloud point extractive determination of arsenic as arsenomolybdenum blue using nonionic surfactant, that is, Triton X-114 at room temperature.

The proposed method is simple and sensitive, and it has been successfully applied to determine trace level arsenic from different environmental and biological samples.2. Experimental2.1. InstrumentationAbsorbance measurements were made using a Shimadzu Scanning Spectrophotometer (model UV-3101PC) with 1cm quartz cuvettes. Calibrated centrifuge tubes with 15mL volume capacity were used to accelerate the phase separation. All pH measurements were carried out using Control Dynamics digital pH meter (model APX 175). ICPAES analysis was carried out using Jobin Yvon Horiba Spectrometer (model Ultima 2). 2.2. Reagents and SolutionsAll chemical reagents used were of Analar grade, and distilled water was used throughout the experiments.

Stock arsenate solution (1000��gmL?1) was prepared by dissolving 0.416g of Na2HAsO4?7H2O AR (SD Fine Chem Ltd., Mumbai, India). Ammonium molybdate solution of 0.015molL?1 was prepared weekly by dissolving 1.85g (NH4)6Mo7O24?7H2O (Merck, Mumbai, India) in 100mL distilled water and storing in refrigerator. About 0.008molL?1 of Sb (III) was prepared by dissolving 0.267g of potassium antimony tartrate (Biddle Sawyer & Co Ltd., Mumbai, India) in 100mL distilled water. Ascorbic acid solution (SD Fine Chem Ltd., Mumbai, India) of about 0.01molL?1 was Brefeldin_A prepared by dissolving 0.176g in 100mL distilled water and storing in refrigerator. Sulfuric acid 1.25molL?1 was prepared by diluting appropriate amount of concentrated acid in cooled distilled water. Triton X-114 (ACROS ORGANICS, NJ, USA) (4% v/v) stock solution was prepared by dissolving 4mL of concentrated solution in hot distilled water. H2O2 (30% w/v) (Qualigens, Mumbai, India) was used for sample digestion.2.3. Sample Collection and Preparation2.3.1.