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Summary. Dispersive liquid-liquid microextraction in combination with an in situ derivatization is suggested for parabens sampling and preconcentration. The derivatization was carried out with acetic anhydride under alkaline conditions maintained using dipotassium hydrogen phosphate. The effects of an extraction solvent type, extraction and disperser solvents volume, extraction time, and ionic strength of the solution on the extraction efficiency were investigated. Chlorobenzene containing n-hexadecane as internal standard was used as an extracting solvent and acetone was used as a disperser solvent. The calibration graphs were linear up to 10 mg mL −1 , correlation coefficients were 0.997-0.999, enrichment factors were from 70 for methylparaben to 210 for butylparaben, and detection limits were 22, 4.2, 3.3, and 2.5 μg L −1 for methylparaben, ethylparaben, propylparaben, and butylparaben, respectively. Repeatabilities of the results were acceptable with relative standard deviations up to 11%. A possibility to apply the proposed method for parabens determination in water samples was demonstrated.

Abstract:A hollow fibre liquid phase microextraction for gas chromatographic determination of some p-hydroxybenzoic acid esters has been developed. Chlorobenzene containing tetradecane as internal standard was used for the extraction. Optimized extraction was carried out at room temperature for 40 min in the presence of 0.4 g mL -1 NaCl in the sample solution. Calibration was linear up to 30 mg L -1 . Correlation coefficients were 0.996 -0.998. Enrichment factors were 21, 95 and 154, and detection limits were 0.20, 0.03 and 0.01 µg mL -1 for methylparaben, ethylparaben and propylparaben, respectively. Reproducibility was acceptable with relative standard deviations up to 11.7%. The technique was tested for water and urine analysis.

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