Derivatization Method for Determination of Nitrosamines by GC-MS

Gas chromatography/low-resolution mass spectrometry with electron impact source was applied to detect eight nitrosamines (NAs). NAs were first denitrosated by a mixed solution of hydrobromic and acetic acids, followed by sulfonylation with p-toluenesulfonyl chloride. Variables affecting the denitrosation and sulfonylation, such as temperature, time, pH and reagent concentration, were optimized. Comparison of the determination of NAs with and without derivatization was performed. Results showed that better chromatographic behavior and larger mass response were obtained after derivatization, and instrumental detection limits ranged from 0.016 to 0.053 ng, a nearly 20-fold decrease of those without derivatization. The proposed method provided an alternative to performing accurate qualitative and quantitative analysis of NAs with expensive high-resolution mass spectrometry or thermal energy analyzer.