Gas Chromatographic determination of parabens after derivatization and dispersive microextraction

Abstract. In this study a dispersive liquid–liquid microextraction method combines with an in situ derivatization. The proposed method is used for the extraction and pre-concentration of some preservatives including methyl paraben, ethyl paraben, propyl paraben and butyl paraben from different water matrices. The extracted compounds are monitored by gas chromatography-flame ionization detector. Parabens are derivatizated by propionic anhydride. The effects of the extraction solvent type, extraction and acylation time, derivative agent volume, temperature, pH and the ionic strength of the solution on the extraction efficiency were investigated. 50 mkl chloroform and 500 mkl acetonitrile is a mixture of suitable extraction and dispersive solvents. The mixture is centrifuged for 3min at 4000 rpm. 20 mkl propionic anhydride is used for derivatization parabens in the concentration range of 0.05 - 1 mg within 2 - 3 minutes. The optimum pH range is 8 - 9. The relative standard deviations (RSDs) of parabens were in the range of 2.0–10.0% (n = 3). The method was applied to the analysis of the four parabens in water. For the analysis of the spiked samples, a recovery above 100 % were obtained