Trace determination of perchlorate using electromembrane extraction and capillary electrophoresis with capacitively coupled contactless conductivity detection

Abstract

Electromembrane extraction (EME) and CE with capacitively coupled contactless conductivity detection (CE-C(4) D) was applied to rapid and sensitive determination of perchlorate in drinking water and environmental samples. Porous polypropylene hollow fiber impregnated with 1-heptanol acted as a supported liquid membrane (SLM) and perchlorate was transported and preconcentrated in the fiber lumen on application of electric field. High selectivity of perchlorate determination and its baseline separation from major inorganic anions was achieved in CE-C(4) D using background electrolyte solution consisting of 7.5 mM L-histidine and 40 mM acetic acid at pH 4.1. The analytical method showed excellent parameters in terms of reproducibility; RSD values for migration times and peak areas at a spiked concentration of 15 μg/L of perchlorate (US EPA recommended limit for drinking water) were below 0.2 and 8.7%, respectively, in all examined water samples. Linear calibration curves were obtained for perchlorate in the concentration range 1-100 μg/L (r(2) ≥0.999) with limits of detection at 1 μg/L for tap water and at 0.25-0.35 μg/L for environmental and bottled potable water samples. Recoveries at 15 μg/L of perchlorate were between 95.9 and 106.7% with minimum and maximum recovery values for snow and bottled potable water samples, respectively.

Electro‐driven extraction of inorganic anions from water samples and water miscible organic solvents and analysis by ion chromatography

“…This may arise out of high viscosity of the SLM solvent, which leads to prevention of diffusion of the anions across the SLM, thus preventing extraction. The obtained results showed that aliphatic alcohols were suitable organic solvents (as SLM) for the extraction of inorganic anions as also demonstrated in earlier works . Also, it was mentioned that acidic compounds were extracted using aliphatic alcohols (especially with 1‐octanol) .…”

“…A, the extraction recoveries of the anions were lower in the acidic and alkaline solutions compared to that of the neutral solutions; therefore, DI water was used as a diluent for the standard solutions in the subsequent EME measurements. The reduced extraction recoveries at the acidic and alkaline conditions can be rationalized by the presence of anions (Cl ¯ and OH ¯ ) in the donor solution that partly hinder the other target anions transfer into the HF lumen . Notwithstanding, phosphate and sulfate ions were extracted in all pHs.…”

“…, 1‐heptanol was perfectly capable of extracting all of the inorganic anions with high recoveries. The same SLM solvent was found to be most suitable for the EME of perchlorate . Alcohols lower than 1‐heptanol suffered from bubble formation and loss of acceptor solution during the extraction process due to the increase in electrical current across the SLM.…”

“…Zhu et al used EME procedure for the extraction of three inorganic anions from an ethyl acetate sample . In another work, the EME combined with CE was applied for the quantification of perchlorate in water samples . Also, Lee et al used the EME procedure for the extraction of biological anions .…”

Inorganic analysis using CE: Advanced methodologies to face old challenges

“…A good deal of effort on developing advanced sample preparation methods was recently invested by Boček and his coworkers. This group has pursued a variety of approaches, such as electrokinetic injection (EKI) or electromembrane extraction , both across a supported liquid membrane, microdialysis , or a membraneless configuration using disposable open tubular ion‐exchange microcolumns , most of which proved to be feasible to handle various proteinaceous samples. Noteworthy is the fact that very small sample volumes (several microliters) could be accommodated; this asset offers an advantage in analysis of such samples, some of which are not available in large quantities.…”