On-line metals preconcentration and simultaneous determination using cloud point extraction and inductively coupled plasma optical emission spectrometry in water samples

A new on-line cloud point extraction (CPE) system coupled to ICP-OES was designed for simultaneous extraction, preconcentration and determination of Cd2+, Co2+, Cr3+, Cu2+, Fe3+ and Mn2+ ions in water samples. This is based on the complexation of the metal ions with 1-(2-thenoyl)-3,3,3-trifluoraceton reagent (TTA) at pH 6.0 in the presence of non-ionic surfactant of Triton X-114. The micellar solution was heated above 60 degrees C and loaded through a column packed with cotton, which acts as a filter for retaining the analyte-entrapped surfactant-rich phase. Then the surfactant-rich phase was eluted using propanol:0.5 mol L-1 nitric acid solution (75:25, v/v) at a flow rate of 3.0 mL min(-1) and directly introduced into the nebulizer of the ICP-OES. Several factors influencing the instrumental conditions and extraction were evaluated and optimized. Under the optimum conditions, the enhancement factors of the proposed method for target ions were between 42 and 97, the detection limits (DLs) were in the range of 0.1-2.2 mu g L-1. The relative standard deviations (R.S.D.s) at 100 mu g L-1 concentration levels of each ion were found to be less than 4.6%. Also, the calibration graphs were linear in the range of 0.5-100 mu g L-1 with the correlation coefficients within the range of 0.9948-0.9994. Finally, the developed method was successfully applied to the extraction and determination of the mentioned metal ions in the tap, well, sea and mineral water samples and satisfactory results were obtained. (C) 2008 Elsevier B.V. All rights reserved.