in order to evaluate exposure of betel quid chewers to n-nitroso compounds , saliva and urine samples were collected from chewers of betel quid with or without tobacco , from tobacco chewers , from cigarette smokers and from people with no such habit , and were analysed for the presence of n-nitrosamines by gas chromatography coupled with thermal energy analyzer and alkaloids derived from betel nut and tobacco by capillary gas chromatography fitted with nitrogen-phosphorous selective detector .
C0028199
nitroso compounds
C0028197
nitrosamines