Quantitative evaluation of perchlorethylene in groundwater before and after its oxidation by helical solid sorbent extraction and gas chromatography

An integrated method of dynamic extraction of perchloroethylene (PCE) with polydimethylsiloxane (PDMS) helical solid sorbent followed by injection into a gas chromatograph was developed for the determination of the real concentration of PCE in groundwater before and after its degradation by oxidation with KMnO4. The main parameters (agitation, temperature, salts, pH) that affect the extraction efficiency have been evaluated and optimized. The increase of the extracted amount of PCE due to the presence of the salts could be partially compensated by the opposite effect of the insoluble MnO2, and of the presence of HCl and the global effect of the matrix would be less important for the reproducibility of the PCE extraction. The quantitative analysis of PCE was carried out with the external standard method using the calibration-curve technique. The limit of detection for PCE was found of 0.05 mg L−1 using flame ionization detector. The solubility of PCE in water was studied by extraction of PCE with PDMS helical solid sorbent from standard solution with different amounts of PCE added into the same volume of water and was found to decrease with settling time, because the fine droplets created during the agitation of the mixture were slowly merged in drops on the bottle walls and were not transferred into the extraction vial for GC analysis. The limit of solubility was evaluated using a graphical method and was estimated at 224.2 ± 15.7 mg L−1 of PCE in water at 25 °C.