At the request of the UK Department of Health, samples of 25 commercial UK cigarette brands were provided to LGC Ltd a for smoke analysis. The brands reflected a high market share (58% in July 2001) and included a wide range of blend and product styles manufactured and imported into the UK.= 0.76), suggesting a minor role of other design features on constituents yield variability. This was confirmed by the application of multiple regression analysis to the data. A subset of five brands, retested at another laboratory, gave between-laboratory differences in mean constituent yields of as much as 2.5-fold. Consideration of these results, other likely sources of analytical variation in this study and a review of other studies, clearly indicates that any tolerance values to be associated with individual smoke constituent measurements will be greater than those for NFDPM, and in some cases, much greater. Consistent with the reported results from other large studies it is concluded that, under ISO smoking conditions, smoke constituent yields are largely predictable, if NFDPM and CO yields are known, for a standard cigarette. Given these observations and the likely limitations of analytical determination, the need for routine measurement of smoke constituent yields, other than NFDPM, nicotine or CO, on standard cigarettes, is questionable.

Regulatory authorities are currently discussing the measurement of and imposition of ceilings on certain smoke analytes, the so called "Hoffmann analytes". However, as a prerequisite, the measurement methods and the tolerances around the measurements first need to be established. In 1999, the Cooperation Centre for Scientific Research Relative to Tobacco (CORESTA) set up a Task Force "Special Analytes" to deal with analytical methodology for measuring "Hoffmann analytes" under International Standard (ISO) smoking and to work towards the standardisation of methods. This paper describes the output and conclusions from a 2005-2006 joint experiment made within the Task Force representing laboratories currently able to analyse these compounds. Data were obtained on most "Hoffmann analytes" from reference cigarettes (2R4F and 1R5F), collecting data according to the existing methods used by the nineteen participating laboratories, in order to describe the within and among laboratory variability and to see which methods could most benefit from more rigorous standardisation work. In some cases, the applied statistical analysis found that methods could not well differentiate the 1R5F and 2R4F cigarettes of differing 'tar' yield. This was explained, in part, by the broad range of methods used by the participating laboratories but also indicated that there were significant inadequacies in the choice of some methods or weaknesses in their application. Results indicate that "Hoffmann Analyte" data are generally more variable both within and among laboratories than nicotine free dry particulate matter (NFDPM); nicotine and carbon monoxide due to their lower smoke yields. Accordingly, tolerances around methods adopted for regulatory purposes will need to be proportionately higher. Methods for benzo[a]pyrene (B[a]P) and tobacco-specific nitrosamines (TSNAs), already taken to CORESTA recommended methods or ISO standardised methods through the efforts of this Task Force, give some of the most reproducible results, showing the value of this process. However, these data strongly suggest that even these analytes have much higher among-laboratory variability than for NFDPM, nicotine and CO and, based on the only two available one point in time studies, may need tolerances in the range of 35-45% for B[a]P and 26-55% for TSNAs, if they are to be measured for regulatory purposes. The collected data is useful to participating laboratories for internal method validation and laboratory accreditation, and data comparisons with others allow laboratories to identify strengths and weaknesses in their current methods. However, much work still needs to be carried out to take most of the methods towards standardisation. Although some fundamental differences or areas of concern around the methodology are discussed herein, they are not comprehensive and there may be others that need to be addressed before methods can be considered ready to take to a Recommended Method and/or to an ISO Standard. These methodological issues are being addressed in furth...

A recommended method has been developed and published by CORESTA, applicable to the quantification of selected carbonyl compounds (acetaldehyde, formaldehyde, acetone, acrolein, methyl ethyl ketone, crotonaldehyde, propionaldehyde and butyraldehyde) in cigarette mainstream smoke. The method involved smoke collection in impinger traps, derivatisation of carbonyls with 2,4-dinitrophenylhydrazine (DNPH), separation of carbonyl hydrazones by reversed phase high performance liquid chromatography and detection by ultra violet or diode array.At the start of the process it was determined that most laboratories participating in the CORESTA Special Analytes Sub-Group (SASG) used a similar method involving such derivatisation and so this was chosen as the basis of the recommended method. Initial joint experiments, specific experiments by single laboratories and ongoing discussions addressed some methodological aspects that needed to be considered before moving to a recommended method.As a first step, a joint experiment by 17 laboratories was carried out in 2009-2010 that investigated three features of the methodology on two reference cigarettes (3R4F and CM6) considered most important by SASG members. These were the volume of the impinger solution (25 or 35 mL); the type of mineral acid (perchloric or phosphoric) used to initiate the derivatisation and the time of derivatisation (5 or 30 min) before terminating the reaction with TrizmaTM base. Overall, it was concluded that these studied parameters in the methodology seemed to have little effect on the overall yield data, compared to the underlying variability among laboratories. The 25 mL impinger solutions appeared to give somewhat higher yields, although not with statistically significant differences, than those obtained when using 35 mL solutions.Some laboratories volunteered to carry out other investigations, for example, to confirm the identity of both the Eand Z-isomeric acetaldehyde hydrazone peaks within the chromatogram of smoke carbonyls and to investigate methodology factors influencing the hydrazoneisomerisation.The CORESTA recommended method (CRM) was produced through a final collaborative experiment involving 15 laboratories from 11 countries using 7 linear and 8 rotary smoking machines. Some notes are included in the CRM to inform other laboratories that might wish to adopt the method, concerning the main features 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 recommendations and are included. As expected from previous work on other smoke components, the levels of reproducibility of carbonyl yields among laboratories are much greater than the levels found for “tar”, nicotine and carbon monoxide and given in the equivalent ISO standards. When expressing the reproducibility (R) value as a percentage of the mean yield among-laboratories and across all of the studied products, values ranged from 67-125% for formaldehyde; from 24-55% for acetaldehyde; from 41-108% for acetone; from 45-73% for acrolein; 31-75% for propionaldehyde; from 63-140% for crotonaldehyde; from 62-90% for 2-butanone and from 42-58% for butyraldehyde. The lowest “tar” yielding product gave the most variable data. These levels are generally in line with those determined for selected volatiles.

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