Chiang Mai Journal of Science

 In the present work, determination of trace manganese in water samples from rivers located in industrial and nonindustrial areas by the simultaneous cloud-point extraction (CPE) and spectrophotometric methods in ternary ion association system was developed. In the proposed method, amphoteric substance of CHAPSO was applied as chelating agent. For this mixed-micelle mediated extraction, CHAPSO, amaranth, triton X-114, trioctylamine (TOA) and NaCl were applied as chelating agent, auxiliary ligand, extraction agent, ion pairing reagent and auxiliary ligand and co-extraction agent, respectively. The various effective parameters on CPE including, pH, type of surfactants and electrolytes, concentration of chelating agent, surfactant, ion pairing reagent (TOA), electrolyte, temperature and duration were investigated. A linear calibration curve in the range of 5-700 µg L^-1 was acquired. Under the optimized conditions, the limit of detection (LOD) was 1.05 µg L^-1and the relative standard deviation (RSD) for 50 and 500 µg L^-1 were 1.43 and 2.71, respectively (n = 10). The regression equation was acquired by the least square method is A = 2.63 ×10^-3C_Mn + 1.67 ×10^-2 with a correlation coefficient of 0.9989 (n = 12), where A is the absorbance and C_Mn shows the concentration of Mn²⁺ in µg L^-1.It is for the first time use of an amphoteric ligand in the field of cloud point extraction and never has been used before that. Considering the achieved results, the manganese quantities, in water samples from the rivers located in industrial areas is considerably higher than the nonindustrial one.