Optimization of Experimental Procedure for Determining Azelaic Acid in Cosmetics by Gas Chromatography Derivatized through Ethanol

The quantitative evaluation of azelaic acid is becoming critical in the development of new medicinal products and in environment. A feasible method for the determination of azelaic acid in cosmetics by gas chromatographic-mass spectrometer detector (GC-MS) with derivation was developed and optimized. The derivative effect was good, when azelaic acid was derivatized through ethanol at room temperature for 10 min with 800 mu L of sulfuric acid as a catalyst. A good linear relationship of azelaic acid derivative was present from 10 to 1000 mg L-1 (R-2 = 0.9997). Detection limit and quantitative limit of GC was 15 and 50 mg kg(-1), respectively. The recovery rate was in the range from 87.7% to 101% with all relative standard deviation (RSD) values less than 4%, denoting the method meeting the requirement of the analysis. Therefore, this method has the advantages of strong anti-interference ability and accurate results. Among the eight samples nominally azelaic acid, only three were detected. The respective content was 78 133, 16 710, and 2431 mg kg(-1). The results showed that the actual addition of the azelaic acid in the market was quite different with label identification, being worthy of further attention. Further, it also provided a favorable experience for the monitoring of azelaic acid in the environment.