Volume 20 (2003): Issue 5 (March 2003)

In this issue of BeitraegezurTabakforschung International/Contributions to Tobacco Research, we publish a ‘Letter to the Editor’ written by R. Baker (p. 360). This letter is a reply to a commentary by S. Shatenstein published in Tobacco Control (11, 174-175, 2002) which provided a critique of a review written by Baker on standards for smoking-machine methodology which appeared in this journal (Beitr. Tabakforsch. Int. 20, 23-41, 2002). The reason why we as editors of Beitraege have decided to publish the letter is simple, the editors of Tobacco Control, the appropriate place for publication, did not allow its publication. In the interest of a fair and scientific discussion of this matter, we think that an author whose paper is criticized publicly should have the chance to reply. However, we regret that Shatenstein's critique and Baker's reply might reach totally different readers.

The reliability of measurements of mainstream smoke analytes other than “tar”, nicotine and carbon monoxide (CO) is not known but is important in the current regulatory environment internationally. An appreciation of between laboratory variability is essential for companies contracting analytical work to outside suppliers.

Seven laboratories obtained data from three cigarette brands for as many as they could currently measure of the 44 smoke analytes, commonly referred to as the “Hoffmann list”. The brands, of “tar” yields 12 mg, 8 mg and 5 mg, were smoked under the International Organisation for Standardisation (ISO) smoking regime to obtain average yield values based on 5 replicates, each laboratory smoking their chosen number of cigarettes per replicate. In addition, laboratories used their preferred and internally validated methodology i.e. smoking machine type, trapping system, sample work-up and detection system. Around 3600 data points were obtained.

This study was based on one point in time measurements. It did not therefore include any components of longer-term variability that would be expected to further increase the measurement variability. No analytes had lower within-laboratory measurement variability than “tar” and 70% of the other analytes had significantly higher levels. All laboratories ranked the products in the same order for all analytes (except some metals) but there were as much as 10-fold differences in measured values between laboratories. The mean difference between highest and lowest yield measurements was 80% when the values for the three smoke analytes with differences in excess of 8-fold were excluded.

Given the lack of standardised methods, and the consequent high degree of inter-laboratory variability it is not currently possible to make meaningful comparisons between such data from several sources. Indeed, calculation of yields from benchmarking studies may prove no less reliable.

This report presents the results of a study regarding the transfer of maleic hydrazide (MH) into mainstream cigarette smoke. Cigarettes with different levels of MH were used in this study. This included cigarettes with MH preexistent in the tobacco due to the agronomical practice, and with spiked MH. Because the MH can be present in tobacco as bound and free forms, both levels of MH were measured in the tobacco section. The cigarette designs covered a range of possibilities, including Plain, Filter King Size (KS), Lights 100’s, Ultra Lights, etc. The results showed that the amount of MH in smoke, on the one hand, is a function of the total particulate matter (TPM) of the cigarette, and higher TPM levels lead to more MH in smoke. On the other hand, the transferred level of MH depends on the total amount of MH (both bound and free) in the tobacco. The relative % transfer is higher for lower MH levels than for higher MH levels in tobacco. When normalized by TPM, the transfer as an average is about 0.24% per mg of TPM from the amount of MH in 1 g of tobacco, and as high as 0.46% per mg of TPM from the amount of MH in 1 g tobacco for a nonfilter low MH level cigarette. The resulting MH transfer for a nonfilter cigarette with low tobacco MH is therefore about 8.3% from the total MH in the cigarette. For filter full flavor (FF) cigarettes with high tobacco levels of MH, the transfer is about 5.8%. This relative transfer rate appears to be lower from higher MH levels in tobacco.

Different approaches have been reported in the literature to reduce the tobacco-specific nitrosamine (TSNA) levels in mainstream smoke (MSS). The reduction of TSNA in the raw tobacco is an approach that has received much attention in recent years. Different elements determine the level of TSNA in MSS: During combustion, part of the TSNA in the cigarette filler can transfer into smoke while another portion can undergo thermal degradation. Moreover, it is possible that TSNA can be pyrosynthesized and that concomitant synergetic effects between the blend components can also occur. Depending on their extent, the formation and degradation of nitrosamines during the combustion process might have an important impact on TSNA level in the smoke of blended cigarettes and might lead to MSS TSNA deliveries which would not parallel that of the blend components.

Three potassium salts of organic acids, namely malate, citrate and tartrate, have been sprayed onto flue-cured blend tobacco and subsequently tested for their performance as burn additives in cigarettes. In one experiment where potassium malate was added to vary the final tobacco potassium from ca. 3.1% to 8.3% (wet weight), an almost linearly reduction in puff temperature was measured. This was accompanied by a gradual increase in the cigarette's pressure drop. In another set of experiments where the final tobacco potassium contents were increased to ca. 5.1%, the three potassium salts showed almost equal reduction in the mainstream nicotine-free-dry-particulate-matter (NFDPM) at 32-35%, nicotine at 25-32% and carbon monoxide at 24-35%. Puff number showed ca. 23% increase with malate, 13% with citrate and almost unchanged for tartrate. Evidence of melting and coating by potassium malate was discovered in cigarette ash by scanning electron microscopy (SEM). This contributed to a noticeable change in ash morphology: small ash particles appeared to be coated and more tightly bonded together by the melt. This phenomenon was thought to be able to restrict the airflow during puffing, hence causing the measured increase in pressure drop, and the reductions in puff temperature, NFDPM, nicotine and carbon monoxide.

A very rapid, flash-gas chromatographic (GC), quantitative method for the analysis of high molecular weight saturated hydrocarbons in cigarette smoke has been developed. The method was fast, accurate and precise. Sample turn around times were approximately six minutes, with an accompanying average percent relative standard deviation (%RSD) of less than 10%. Four linear saturated hydrocarbons with 27, 29, 31 and 33 carbon atoms were quantitated in an array of reference cigarettes ranging in “tar” deliveries from approximately 2 to approximately 20 mg. By use of a cyclohexane extraction of cigarette smoke captured on Cambridge filter pads, the extraction efficiency was determined to be greater than 95% for each hydrocarbon. The approach represents a significant advance over current analytical procedures that require, on average, greater than 30-min sample turn around times.

The color of Oriental tobaccos was organoleptically assayed, and high performance liquid chromatography (HPLC) of polyphenols was performed. The major tobacco polyphenols (chlorogenic acid, its isomers, and rutin), as well as scopoletin and kaempferol-3-rutinoside were quantified. HPLC polyphenol profiles were processed by pattern recognition method (PRM), and the values of indexes of similarity (Is,%) between the cultivars studied were determined. It was shown that data from organoleptic color assessment and from PRM based on HPLC profiles of polyphenols of the cultivars studied are largely compatible. Hence, PRM can be suggested as an additional tool for objective color evaluation and classification of Oriental tobacco.