Abstract:
Objective To establish a high⁃performance liquid chromatography （HPLC） quantitative method for the determination of epicatechin （EC）， （-）⁃epicatechin gallate （ECG）， （-）⁃epigallocatechin （EGC）， （-）⁃epigallocatechin gallate （EGCG）， （-）⁃gallocatechin （GC）， （-）⁃gallocatechin gallate （GCG）， （-）⁃catechin gallate （CG）， cianidanol （CD） and gallic acid （GA） in cosmetics.
Methods Samples were prepared by ultrasonic extraction and followed by high-speed centrifugation of the extraction solution. The supernatant was filtered by 0.45 μm Millipore filter. The continued filtrate was taken for analysis. A reversed phase column， Kromasil 100-5 C18 （5 μm， 4.6 mm×250 mm） was used with 0.05% trifluoroacetic acid buffer and methanol as mobile phase under the condition of gradient elution. Diode array detection （DAD） method was used for the determination. Qualitative and quantitative determination was conducted in 10 batches of commercially available cosmetics.
Results The relative standard deviations （RSD） were in the range of 0.11%-6.30% （n=3）； the recoveries were in the range of 84.4%-114.7%. The method showed a good linearity within the concentration range of 0.49-105.39 mg·L-1 （r>0.995）. The detection limit was 5 μg·g-1. In 10 batches of commercially available cosmetics， three batches showed positive result， which was consistent with the UV spectrum of the standard.
Conclusion This method is efficient， sensitive and accurate. It is applicable to the determination of EC， ECG， EGC， EGCG， GC， GCG， CG， CD and GA in cosmetics.
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