Application of cotton as a solid phase extraction sorbent for on-line preconcentration of copper in water samples prior to inductively coupled plasma optical emission spectrometry determination

Abstract

Copper, as a heavy metal, is toxic for many biological systems. Thus, the determination of trace amounts of copper in environmental samples is of great importance. In the present work, a new method was developed for the determination of trace amounts of copper in water samples. The method is based on the formation of ternary Cu(II)–CAS–CTAB ion-pair and adsorption of it into a mini-column packed with cotton prior applying inductively coupled plasma optical emission spectrometry (ICP-OES). The experimental parameters that affected the extraction efficiency of the method such as pH, flow rate and volume of the sample solution, concentration of chromazurol S (CAS) and cethyltrimethylammonium bromide (CTAB) as well as type and concentration of eluent were investigated and optimized. The ion-pair (Cu(II)–CAS–CTAB) was quantitatively retained on the cotton under the optimum conditions, then eluted completely using a solution of 25% (v/v) 1-propanol in 0.5 mol L −1 HNO 3 and directly introduced into the nebulizer of the ICP-OES. The detection limit (DL) of the method for copper was 40 ng L −1 ( V sample = 100 mL) and the relative standard deviation (R.S.D.) for the determination of copper at 10 μg L −1 level was found to be 1.3%. The method was successfully applied to determine the trace amounts of copper in tap water, deep well water, seawater and two different mineral waters, and suitable recoveries were obtained (92–106%).