On-line concentration and separation of parabens by micellar electrokinetic chromatography using polymer solutions

Abstract

Simultaneous separation and quantification of seven parabens commonly used as preservatives in cosmetic products, by micellar electrokinetic chromatography with a 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 sulphate (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 930-2200-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 determination of parabens in commercial cosmetic products. Procedures for the on-line concentration and separation of parabens using micellar electrokinetic chromatography in the presence of electroosmotic flow and poly(ethylene oxide) solution containing sodium dodecyl sulfate. Copyright © 2014 The Chemical Society Located in Taipei & Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim, Germany.