Ionic liquid as a complexation and extraction medium combined with high-performance liquid chromatography in the evaluation of chromium(VI) and chromium(III) speciation in wastewater samples

✍ Scribed by Li-Yan Ying; Hai-Liang Jiang; Sai-cun Zhou; Yi Zhou

• Publisher: Elsevier Science
• Year: 2011
• Tongue: English
• Weight: 383 KB
• Volume: 98
• Category: Article
• ISSN: 0026-265X
• DOI: 10.1016/j.microc.2011.01.010

✦ Synopsis

A simple method has been proposed for the determination of chromium species by high-performance liquid chromatography (HPLC) after preconcentration by the ionic liquid, 1-butyl-3-methyimidazolium hexafluorophosphate ([C 4 MIM][PF 6 ]). The simultaneous preconcentration of Cr(VI) and Cr(III) in wastewater was achieved with ammonium pyrrolidinedithiocarbamate (APDC) as the chelating agent and the ionic liquid [C 4 MIM][PF 6 ] as the extractant. Baseline separation of the APDC chelates of Cr(III) and Cr(VI) was realised on a RP-C18 column using a mixture of methanol-acetonitrile-water (53:14:33, v/v) as the mobile phase at a flow rate of 1.0 mL min -1 . The influences of several variables on the complexation and extraction were evaluated: pH, reaction time, APDC concentration and metal ion interference. Our results showed that when the linear concentration of Cr(VI) and Cr (III) ranged from 25 to 200 μg L -1 , their linear correlation coefficients were between 0.9977 and 0.9978, their recoveries ranged from 91.8% to 95.8% and their relative standard deviations (n= 3) were between 0.31% and 1.8%. Common metal ions in water did not interfere with the determination. This method is a simple, fast, accurate, highly stable and selective method and has successfully been applied to the speciation of chromium in wastewater.