However, the signal to noise ratio is much superior at 690nm when compared to 840nm, hence all absorbance measurements have been carried out at 690nm in the present investigations.Figure 1Absorption spectra of arsenomolybdenum our site blue complex after cloud point extraction.3.1. Optimization StudyThe initial studies were carried out by extracting the formed arsenomolybdenum blue complex into nonionic surfactants like Triton X-100 and Triton X-114 as the TX series of nonionic surfactants have several advantages over other surfactants like commercial availability, low toxicity, low cloud point formation temperature and high density of the surfactant-rich micellar phase [13]. The quantitative extraction of the complex was obtained by both the surfactants, but, in case of Triton X-100, heating is required for cloud formation but in presence of Triton X-114, cloud formation takes place at room temperature.

Hence, Triton X-114 was used as a micellar phase to preconcentrate the analyte species before absorbance measurement. All the parameters influencing the complex formation and cloud point extraction have been optimized.3.1.1. Effect of Acidity The arsenomolybdenum blue complex forms in acidic medium; hence, the effect of sulfuric acid concentration on complex formation has been studied. The higher absorbance values corresponding to the sample versus reagent blank were obtained at an overall acidity value of 0.25M. The required acidity was achieved by the addition of 2mL of 1.25 molL?1 sulfuric acid and used in all further studies (Figure 2).Figure 2Effect of overall acidity.

3.1.2. Effect of Surfactant The effect of surfactant concentration on the quantitative phase separation of analyte through micelle is a crucial parameter in cloud-point-extraction based methods. Hence, we have examined two nonionic surfactants like GSK-3 Triton X-100 and Triton X-114 for the quantitative separation of the complex. Quantitative extraction of the complex from the aqueous phase was obtained by both surfactants, but the extraction of the complex at room temperature was achieved only with Triton X-114. The high density of Triton X-114 facilitates quick phase separation which can be easily achieved by simple centrifugation [16]. In case of Triton X-100, heating is required to attain cloud point temperature whereas Triton X-114 attains clouding at normal condition itself, that is, at room temperature [9]. Hence, Triton X-114 has been selected as a micellar phase for analyte separation. Quantitative extraction of the complex was achieved at 0.8% (v/v). The required surfactant concentration was achieved by the addition of 2mL of 4% surfactant solution (Figure 3).Figure 3Effect of Triton X-114 concentration.3.1.3.