摘要：A simple method for the determination of C12, C14, C16, C18, C20, C22 and C24 alkyltrimethylammonium chlorides in cosmetics by injection port pyrolysis gas chromatography (GC) was investigated. The conditions of GC were as follows : glassinsert, loaded some of quartz wool ; injection port temperature, 320°C ; column : DB-1 (0.53 mm i.d. × 15 m) ; column temperature, 100→300°C (5°C/min) ; detector, FID. The alkyltrimethylammonium chlorides injected into the gas chromatograph were thermally decomposed to the corresponding alkyldimethylamines as major peaks and alkyl chlorides as minor peaks. The decomposition products were identified by chemical ionization (isobutane) mass spectrometry (MS) on a GC-MS and characterized with the quasi-molecular ions, (M+1)+ for alkyldimethylamines and (M-1)+ for alkyl chlorides, respectively. The calibration curves obtained by plotting the peak area of the alkyldimethylamines were linear at levels ranging from 100 to 800 μg/ml of C12-C24 alkyltrimethylammonium chlorides. The detection limit was 30 μg/ml in sample solution. The average recoveries of C12-C24 alkyltrimethylammonium chlorides added to hair rinse at levels of 0.5 and 1.0% in five experiments were 99.6-103.4% and the coefficients of variation were 1.2-2.5%. This method is useful for the simultaneous determination of C12-C24 alkyltrimethylammonium chlorides and suitable for the routine analysis of cosmetics.
关键词：alkyltrimethylammonium chloride;quarternary ammnonium salt;injection port pyrolysis;chemical ionization mass spectrometry;cosmetic;GC
