Determination of nine volatile nitrosamines and hydroxy-nitrosamines in cigarette filler and mainstream tobacco smoke using isotope-dilution LC-MS/MS
Volatile nitrosamines (VNA) and N-nitrosodiethanolamine (NDELA) in tobacco and tobacco smoke have been traditionally quantified using multi-step procedures involving either chemoluminescence (GC-TEA) or more recently mass spectrometric (GC-MS) techniques. The high cost and complexity associated with these procedures prompted an investigation into alternative analytical approaches. As a result, a new liquid chromatography/tandem mass spectrometric method was developed utilizing LC-MS/MS for the analysis of nine nitrosamines and NDELA in cigarette filler and mainstream smoke.
VNA were collected by passing mainstream tobacco smoke through two traps, each containing 25 mL of an ammonium sulfamate /sulfuric acid buffer solution, followed by a treated Cambridge filter pad. Isotopically labeled nitrosamines, used as internal standards, were added to the trapping solution then used to extract the filter pad (30 minutes, wrist-action shaker). For tobacco filler, the internal standard mixture was added to the sample, extracted with 50 mL of water at 40°C for 16 hours, then acidified using ammonium sulphamate/sulphuric acid and saturated with ammonium sulphate. In both cases (smoke and filler) an aliquot of the extract was partitioned using a ChemElut® cartridge with ethyl formate containing 2% ethanol as eluent. Further clean-up was required for the hydroxyl-nitrosamines, consisting of a florisil SPE clean-up of the extract using methanol as eluent. The solvent was evaporated and the concentrated sample analyzed by LC-APCI+-MS/MS, with the analyzer operating under multiple reaction monitoring mode.
The method showed excellent recovery with values ranging from 98 to 111% for lab fortified matrix samples, with a good precision (ca. 10%). The method limits of quantification range between 1-10 ng/cig under ISO smoking regimen and 0.2-0.4 ng/g in cigarette filler.