Determination of Cadmium at Trace Levels in River Water Samples by Simultaneous Ion-Pairing and Mixed Micelle Extraction Prior to UV-Vis Spectrophotometry

Abstract

A procedure for simultaneous separation/preconcentration of cadmium in water river samples, based on cloud point extraction (CPE) as a prior step to its determination by spectrophotometric method in a ternary ion association system has been developed for river water samples. The preconcentration was applied using simultaneous [Cd (SCN4)]-2 complexation and forming ternary ion association system with Toluidine Blue-O (TBO) and cationic surfactant N-cetyl-N-N-N-trimethyl ammonium bromide (CTAB), accordingly. The hydrophobic complex was quantitatively entrapped with octylphenoxy- polyethoxyethanol (Triton X-114) from aqueous solution. The parameters affecting the extraction efciency of the proposed method, such as sample pH, complexing agent concentration (SCN-,TBO+ and CTAB), buffer amount, ionic and non ionic surfactant concentration, temperature, and incubation time were optimized. The relative standard deviation (RSD) for nine replicate determinations at 50 mg L-1 of cadmium was 3.11%. The resultant limit of detection (LOD) and limit of quantification (LOQ) were 2.1 and 7 mg L-1, respectively. The calibration graph was linear with a correlation coefcient of 0.9985 in the range of 7-1000 mg L-1 of cadmium.