Abstract. In this study a dispersive liquid-liquid microextraction method combines with in situ derivatization. The proposed method was used for the extraction and preconcentration of some preservatives including methylparaben, ethylparaben, propylparaben and butylparaben from water matrices. The extracted compounds were determined by gas chromatography -flame ionization detector. Derivatization of parabens was carried out using propionic anhydride. The effects of the extraction solvent type, extraction and acylation time, derivative agent's volume, temperature, pH and ionic strength of solution on the extraction efficiency were investigated. 50 L of chloroform and 500 L of acetonitrile was applied as a mixture of suitable extraction and dispersive solvents.The mixture is centrifuged for 3 min at 4000 rpm. 20 L of propionic anhydride is used for the derivatization of parabens in the concentration range of 0.05 -1 mg L -1 within 2 -3 minutes. The optimum pH range was 8,0 -9,0. The limits of detection (LOD) were 0,003 mg/L for methyl-, ethylparabens; 0,002 mg/L for propyl-, butylparabens, relative standard deviations (RSDs) were in the range of 2.0-10.0 % (n = 3, P = 95 %). The method was applied to the analysis of the four parabens in water. For the analysis of the spiked samples, the recovery above 100 % was obtained.
Abstract. In this study, solid-phase microextraction method combines with gas chromatographyflame ionization detector. The proposed method is used for the preconcentration of some benzophenones. Influence of different factors on the efficiency of extraction is described in detail.The analytical procedure was optimized for fiber coating selection, extraction time, temperature, sample pH, ionic strength. For all benzophenones, the highest enrichment factors were achieved using carboxen/polydimethylsiloxane/divinylbenzene fibre immersed directly into the water samples, containing 100 mg/mL of sodium chloride, at room temperature. The optimum pH range is 5.0 -7.0. The relative standard deviations (RSDs) were from 1.3 to 10.0 % (n = 3). The method was applied to the determination of benzophenone, benzophenone-3, 2-hydroxybenzophenone in the lake water and urine.
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