Simultaneous Determination of Six Preservatives in Maxing Zhike Syrup by MEKC-DAD

OBJECTIVE To establish a micellar electrokinetic chromatography with diode array detection(MEKC-DAD) method for simultaneous determination of six preservatives including benzoic acid, sorbic acid, methylparaben, ethylparaben, propylparaben and butyl-p-hydroxybenzoate in Maxing Zhike syrup. METHODS Based on the mode of MEKC, an uncoated fused silica capillary(75 μm×64 cm, 56 cm of effective length) was adopted, and 15 mmol·L^-1borax-60 mmol·L^-1boric acid-50 mmol·L^-1SDS was selected for the running buffer. The detection wavelength was set at 195 nm. The separation voltage was 15 kV and the column temperature was maintained at 20℃. The sample was injected at 50 mbar for 5 s. RESULTS The calibration curves of the six preservatives in Maxing Zhike syrup showed good linearity(r ≥ 0.999 3). RSDs of precision and stability test were <2.0%. The average recoveries of the method were between 98.7%-101.2%(n=9). No sorbic acid and parabens were detected in 10 batches of samples from 5 enterprises. The benzoic acid content of samples from 5 enterprises was consistent with the prescription. CONCLUSION The method is suitable for the detection of preservative in Maxing Zhike syrup. The obtained results are valuable for its manufacturing process and quality control.