Extraction of carbonyl derivatives from ozonated wastewater samples using hollow fiber liquid phase microextraction followed by gas chromatography-electron capture detection

Abstract

Herein, a simple and sensitive method was successfully developed for the extraction and quantification of seven carbonyl compounds (acetaldehyde, propanal, butanal, pentanal, hexanal, glyoxal, methylglyoxal) in a number of wastewater samples previously treated by ozonation process. The compounds were initially derivatized (derivatizing reagent (PFBHA)) and then extracted by a hollow-fiber liquid-phase microextraction method (HF-LPME) in the aqueous sample solution. Afterwards, the extraction solvent was withdrawn from the fiber and injected to a gas chromatograph equipped with electron capture detection (GC–ECD). Factors affecting the extraction efficiency of the whole procedure were optimized using a univariate approach. Under the optimal conditions obtained (sample solution pH, 4; organic extraction solvent, dihexylether; stirring rate, 1000 rpm; no salt addition; and extraction time of 40 min), limits of quantification were 0.5–0.8 μg/l for the studied carbonyl compounds. Dynamic linear ranges were 0.5–100 μg/l for five targets (acetaldehyde, propanal, butanal, pentanal and hexanal) and 0.8–80 μg/l for two targets (glyoxal and methylglyoxal). The relative standard deviations (RSDs %) representing the precision of the method were in the range of 6.4–11.9 based on the average of three measurements. Accuracy of the method was also tested by the relative recovery experiments on spiked samples, with results ranging from 85 to 113%. Finally, the method could be used for routine screening of carbonyl compounds in complex matrices.