Determination of N-nitrosodiethanolamine in cosmetic products by headspace solid phase microextraction using a novel aluminum hydroxide grafted fused silica fiber followed by gas chromatography–mass spectrometry analysis

A method based on headspace solid phase microextraction with a new fiber, coupled with gas chromatography–mass spectrometry was developed for the determination of NDELA in cosmetic samples. The fiber provides Lewis acid–base interaction between its surface and analyte functional groups. The fiber was prepared by grafting aluminum tri-tert-butoxide on the surface of a fused silica. The optimization of SPME conditions showed that NDELA can be most effectively extracted at 70 °C, in 15 min, with a sample volume of 0.5 (Vs/Vt), stirring rate of 150 rpm, desorption time of 5 min, desorption temperature of 260 °C and at 12.5% (w/w) concentration of NaCl. Under the optimized conditions, LOD of 1 μg Kg−1 and a calibration curve with correlation coefficients greater than 0.9897 and a linearity range from 6 to 10000 μg Kg−1 were obtained. The intra-day and inter-day precision and accuracy were evaluated at four concentration levels. All of the values for accuracy and precision were lower than the acceptable limit of 15%. The fiber to fiber repeatability was 8.7%. The method was applied for the analysis of real samples including hair shampoo, body shampoo, dishwashing liquid and hand washing liquid. Relative recoveries were achieved in the range of 95–99%.