Abstract:

A gas chromatography-tandem mass spectrometry （GC-MS/MS） method was established for the simultaneous detection of 14 N-nitrosamines （N-nitrosodimethylamine, N-nitrosoethylmethylamine, N-nitrosodiethylamine, N-nitrosoethylisopropylamine, N-nitrosodiisopropylamine, N-nitrosoethylpropylamine, N-nitrosodipropylamine, N-nitrosodibutylamine, N-nitrosomethylaniline, nitrosoethylphenylamin, N-nitrosopiperidine, N-nitrosopyrrolidine, N-nitrosomorpholine, N-nitrosodiphenylamine） in hair dyes. Pretreating based on QuEChERS method, the analytes were separated by polyethylene glycol quartz capillary gas chromatographic column HP-INNOWAX （30 m×0.25 mm×0.25 µm） following the GC temperature program. Mass spectrometric ionization was undertaken in electron impact （EI） ionization mode, and the MS detector was operated in multiple reaction monitoring （MRM） mode including quantitative ion pair and qualitative ion pair for all analytes. The correlation coefficients of the standard calibration curves are greater than 0.998 in the range of 5-100 μg/L. The limits of detection are 0.2-1.5 µg/L, and the limits of quantification are 0.6-5 µg/L, respectively. The average recoveries of 14 N-nitrosamines range from 83.8% to 122.8% at the spiked levels of 25, 50 and 100 µg/kg, with the relative standard deviations （RSDs） less than 11% （n=6）. N-nitroso-n-methylaniline is detected at the level of 31 µg/kg in one hair dye sample. The developed method is simple, rapid, exclusive, sensitive, accurate and precise. This method can be applied in the identification and quantitative of 14 N-nitrosamines in hair dyes.

Key words: gas chromatography-tandem mass spectrometry, hair dyes, N-nitrosamines