Volatile nitrosamines in cigarette smoke: a new sampling and analytical method
Volatile nitrosamines (VNAs) in cigarette smoke are formed from decarboxylation of N-nitrosoaminoacids or pyrolitic nitrosation of secondary amines. Previous studies show that the levels of VNAs are much higher in sidestream smoke than mainstream smoke. Selective removal of VNAs from the mainstream smoke is achieved by cellulose acetate filters. A new selective and sensitive method to collect and detect VNAs in tobacco smoke by gas chromatography coupled to a Thermal Energy Analyzer (GC-TEA) is under investigation. The set up chromatographic method is able to identify N-Nitrosodiphenylamine (NDPHA), Nnitrosodimethylamine (NDMA), N-Nitrosopyrrolidine (NPYR), N-Nitrosodi-n-butylamine (NDBA), N-Nitrosodiethylamine (NDEA), N-Nitrosomethylethylamine (NMEA), N-Nitrosomorpholine (NMOR), N-Nitrosopiperidine (NPIP), N-Nitrosodi-n-propylamine (NDPA). Ten cigarettes were smoked under controlled conditions. The mainstream and sidestream particulate phases were collected on a 44 mm Cambridge filter. The vapor phase of sidestream smoke was captured by two impinger solutions placed after the Cambridge pad. The impingers contained isopropanol solution and were cooled by ice-cooled water in a Dewar flask. The total particulate matter trapped on the Cambridge filters was extracted with dichloromethane (DCM) in an ultrasonic bath for one hour. The pooled isopropanol solution and the dichloromethane extracts were concentrated up to 2 ml and analysed by GC-TEA. Different extraction solutions (DCM, isopropanol, 1/1 DCM/Acetone solution) and different impinger solutions (isopropanol, 1% HCl) were compared. A clean-up procedure was tested. The recovery rates for each solution were assessed by spike experiments of standard solution on both smoked and unsmoked filters. NDMA and NPYR in sidestream and mainstream smoke were quantitatively determined. NMEA and NMOR were detected in sidestream smoke only.