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摘要:
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Simultaneous separation and quantification of seven parabens methyl, ethyl, isopropyl, propyl, isobutyl, butyl, and benzyl p-hydroxybenzoate, commonly used as preservatives in cosmetic products, by micellar electrokinetic chromatography with an on-line sample stacking technique has been demonstrated. An effective on-line concentration strategy involving a combination of sweeping and the use of polymer solutions is a key feature of the proposed method, which successfully determined individual parabens. The analysis parameters such as injection time, pH and concentration of phosphate solution, and concentration of sodium dodecyl sulfate (SDS) and poly(ethylene oxide) (PEO) were examined. The optimum conditions were found to be as follows: a 15 mM phosphate solution (pH 9.5) containing 20 mM SDS for filling the capillary, and for the separation electrolytes, 0.100% PEO (8 MDa) added to the phosphate and SDS solution of the same composition as for the capillary. The entire analysis process was completed in 13 min and a 931–2199-fold enhancement factor was achieved. The LODs (S/N = 3) for this approach were in the range from 4.32 to 7.78 nM. The linear range for each paraben was between 50 nM and 5.0 μM (R2 > 0.990). The optimized method was then successfully applied to the simultaneous determination of these parabens in commercial cosmetic products.
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