Solid-Phase Extraction Followed by Dispersive Liquid-Liquid Microextraction Based on Solidification of Floating Organic Drop for the Determination of Parabens

A dispersive liquid-liquid microextraction based on solidification of floating organic drop method combined with solid-phase extraction (500-mg C-18 sorbent) was developed for preconcentration and determination of some parabens. The experimental parameters influencing the extraction efficiency such as the type of extraction and disperser solvents, as well as their volumes, breakthrough volume, flow rate and salt addition were studied and optimized. The optimum experimental conditions found included: sample volume, 100 mL; KCl concentration, 1% (w/v); extraction solvent (1-undecanol) volume, 20 mL and disperser solvent (acetone) volume, 250 mu L. Under the optimum experimental conditions, calibration graphs were linear in the range of 1-200 mu g L-1 with limits of detection ranged from 0.3 to 1.7 mu g L-1. The relative standard deviations were in the range of 1.2-3.1% (n = 5). The enrichment factors and absolute recoveries of parabens in different matrices were 245-1886 and 9.0-69.8%, respectively. The method was applied to the simultaneous determination of parabens in different matrices. The relative recoveries from water, shampoo and mouth rinse samples, which have been spiked at different levels of parabens, were 87.83-112.25%, 82.80-108.40% and 90.10-97.60%, respectively.