Simultaneous derivatization and microextraction of parabens in different matrices followed by GC-FID

Abstract

In this study, a simple, rapid, and an economical method has been proposed for the extraction, preconcentration, and determination of parabens (methyl-, ethyl-, and propylparaben) in different samples based on derivatization by acetic anhydride and preconcentration using air-assisted liquid–liquid microextraction in a single step. In this method, 1,1,2,2-tetrachloroethane (extraction solvent) containing μL-level of acetic anhydride (derivatization agent) is injected into aqueous sample containing parabens and picoline (catalyst). The mixture of aqueous and organic phases is withdrawn into a glass syringe and then injected into the test tube for several times till a turbid solution is obtained. After centrifuging, 1 μL of the sedimented phase is injected into gas chromatography-flame ionization detector. The effect of catalyst volume, derivatization agent volume, extraction solvent type and volume, ionic strength of the solution, pH, and numbers of extraction on the extraction efficiency is investigated. Under the optimal conditions, the enrichment factors and enhancement factors for the parabens were obtained in the ranges of 310–353 and 2,484–5,298, respectively. Limits of detection were between 0.18 and 8.5 µg L−1. The method was found to be linear over the range of 10–10,000 μg L−1 with good coefficients of determination (R2 > 0.999). The obtained extraction recoveries ranged from 69 to 107 % and precision of the method, expressed as relative standard deviation (RSD %), was within the range of 4.0–13 %. The proposed method was successfully applied for determination of parabens in different samples such as cream, toothpaste, and mouthwash.