Determination of Tobacco Specific Nitrosamines in Cigarette Mainstream Smoke: The CORESTA 2011 Collaborative Study

Abstract

Abstract A CORESTA Recommended Method (CRM 75) has been developed and published, applicable to the quantification of tobacco-specific nitrosamines (TSNAs), namely, Nnitrosonornicotine (NNN), N-nitrosoanabasine (NAB), Nnitrosoanatabine (NAT) and 4-(N-nitrosomethylamino)-1-(3-pyridyl)-1-butanone (NNK) in cigarette mainstream smoke. The method involves smoke collection on a Cambridge filter pad under both ISO 3308 and the intense conditions adopted by Health Canada. An internal standard solution is added to the smoke collected on the pad and, after extraction, an aliquot is separated and quantitatively analysed by liquid chromatographytandem mass spectrometry (LC-MS/MS). CRM 63 involving gas chromatography coupled with a thermal energy analyser (GC-TEA) was previously developed by the CORESTA Special Analytes Group that had been set up to develop recommended methods on smoke components. However, by 2009 most laboratories had moved to similar LC-MS/MS methods for TSNA analysis and so this technique was chosen as the basis of a new CRM and to complement CRM 63. Initial joint experiments, specific experiments by single laboratories and ongoing discussions identified methodological aspects that needed to be ‘standardised’ before moving to a CRM. A joint experiment by 15 laboratories was carried out in 2010-2011 that investigated and identified important methodological features that needed to be controlled or clarified. CRM 75 was produced through a final collaborative experiment involving 20 laboratories from 12 countries using both linear and rotary smoking machines. Some notes are included in the CRM to inform other laboratories that might wish to adopt the method, concerning aspects that need to be well controlled to provide data as robust as possible and to provide similar repeatability and reproducibility data. Statistical evaluations were made according to ISO 5725 guidelines and are included. Under ISO smoking, the levels of reproducibility (R) expressed as a percentage of the mean of TSNA yields across laboratories are much greater than the levels found for “tar”, nicotine and carbon monoxide and given in the relevant ISO standards. The R value was expressed as a percentage of the mean yield amonglaboratories and across all of the studied products. Under ISO smoking R% values ranged from 25-60% for NNN; from 31-85% for NNK; from 47-58% for NAT and 40-99% for NAB. These levels are generally in line with those determined previously for TSNAs in CRM 63 and for other smoke analytes studied by the Special Analytes Group. Under ‘intense’ smoking, R% values ranged from 30-88% for NNN; from 37-79% for NNK; from 47-83% for NAT and 42-111% for NAB. A plot of R against mean yields suggests that the ‘intense’ regime gives similar or slightly worse reproducibility than the ISO regime in spite of the higher yields generated.