Determination of cadmium(II), cobalt(II), nickel(II), lead(II), zinc(II), and copper(II) in water samples using dual-cloud point extraction and inductively coupled plasma emission spectrometry

• Published in: Journal of hazardous materials 2012-11, Vol.239-240, p.206-212
• Main Authors: Zhao, Lingling, Zhong, Shuxian, Fang, Keming, Qian, Zhaosheng, Chen, Jianrong
• Format: Article
• Language: English
• Subjects: 8-Hydroxyquinoline; Dual cloud point extraction; Heavy metal ion; Inductively coupled plasma optical emission spectrometry; Metals, Heavy - analysis; Oxyquinoline - chemistry; Polyethylene Glycols - chemistry; Pre-concentration and separation; Spectrum Analysis - methods; Surface-Active Agents - chemistry; Water Pollutants, Chemical - analysis
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/j.jhazmat.2012.08.066

► A dual-cloud point extraction (d-CPE) procedure was firstly developed for simultaneous pre-concentration and separation of trace metal ions combining with ICP-OES. ► The developed d-CPE can significantly eliminate the surfactant of Triton X-114 and successfully extend to the determination of water samples with good performance. ► The designed method is simple, high efficient, low cost, and in accordance with the green chemistry concept. A dual-cloud point extraction (d-CPE) procedure has been developed for simultaneous pre-concentration and separation of heavy metal ions (Cd2+, Co2+, Ni2+, Pb2+, Zn2+, and Cu2+ ion) in water samples by inductively coupled plasma optical emission spectrometry (ICP-OES). The procedure is based on forming complexes of metal ion with 8-hydroxyquinoline (8-HQ) into the as-formed Triton X-114 surfactant rich phase. Instead of direct injection or analysis, the surfactant rich phase containing the complexes was treated by nitric acid, and the detected ions were back extracted again into aqueous phase at the second cloud point extraction stage, and finally determined by ICP-OES. Under the optimum conditions (pH=7.0, Triton X-114=0.05% (w/v), 8-HQ=2.0×10−4molL−1, HNO3=0.8molL−1), the detection limits for Cd2+, Co2+, Ni2+, Pb2+, Zn2+, and Cu2+ ions were 0.01, 0.04, 0.01, 0.34, 0.05, and 0.04μgL−1, respectively. Relative standard deviation (RSD) values for 10 replicates at 100μgL−1 were lower than 6.0%. The proposed method could be successfully applied to the determination of Cd2+, Co2+, Ni2+, Pb2+, Zn2+, and Cu2+ ion in water samples.