A fast method for simultaneous analysis of methyl, ethyl, propyl and butylparaben in cosmetics and pharmaceutical formulations using capillary zone electrophoresis with UV detection

Abstract

The development and optimization of a novel methodology for simultaneous analysis of methyl, ethyl, propyl, and butylparaben using capillary zone electrophoresis under direct UV detection at 297 nm was proposed. The background electrolyte optimization was performed with the aid of Peakmaster® software simulation. The optimized background electrolyte was composed of 20 mmol L⁻¹ of 2-hydroxyisobutyric acid, 30 mmol L⁻¹ of triethylamine, and 0.3 mmol L⁻¹ of hexane-1,6-bis(triethylammonium) bromide at pH 10.6. A capillary with a total length of 32 cm, an effective length of 8.5 cm and 50 μm internal diameter was used. Analysis was performed at 25 °C and 30 kV with positive polarity in the injection side. The optimized method presented acceptable linearity within the range of 0.5 to 30 mg L⁻¹ (R² > 0.99), limit of detection of 0.1 mg L⁻¹ and limit of quantification from 0.3 to 0.4 mg L⁻¹. The optimized method was successfully applied to analysis of these parabens in several cosmetics and pharmaceutical formulation samples in the absence of pre-treatment and a run time of about 1.0 min, being the fastest in the literature. For this, short-end injection mode was used. At the end, the results found in real samples were compared to LC-MS/MS, which proved the accuracy of the method.