The Technical Committee ISO/TC 126 ‘Tobacco and tobacco products’ of the International Organization for Standardization set up Working Group 7 to develop and test a method for the determination of ‘tar’ and nicotine yield when fine-cut smoking articles (FCSAs) are smoked by routine-analytical smoking machines. FCSAs are individually made by consumers using tobaccos manufactured for enclosure in paper wrappers (i.e. leaflets and tubes - with or without filters). This paper records the history of method development, defines terms and explains the differences between measurements made on FCSAs and commercially factory made cigarettes. Individual consumer making practices are represented by the specification of four hand-made article types using two wrappers of different physical properties each with either 400 mg or 750 mg tobacco.
ISO standards require estimates of the repeatability (r) and reproducibility (R) of analytical methods, so the working group has conducted a collaborative study. The values ofr andR were determined using the definitions given in ISO 5725-2 (18). Twenty laboratories took part and tested three different commercial tobacco blends according to the standard method. The detailed protocol for the study is given in Annex A. Annex B is an illustrated manual used as a training aid for laboratory personnel with little experience of making FCSAs. After the smoking was completed, the laboratory data were examined for outlying points by the methods of Grubbs and Cochran. It was found necessary to exclude the data from one laboratory prior to statistical analysis otherwise the incidence of outliers was low (1.41%). Values ofr andR were calculated from the results of one-way analyses of variance (within and between laboratories) for smoke nicotine and nicotine-free dry particulate matter (NFDPM). The data for the 19 laboratories are given in Annex C. The quality of the data is high as is shown by the comparisons made between ther andR values for the articles and those for the monitor test pieces which were used to confirm that smoking conditions run-to-run were satisfactory. The range of NFDPM and smoke nicotine yields resulting from the four designs of articles is large for each of the three blends. The measured NFDPM yields of the four designs are ranked in the same order by all of the laboratories and all pairs are statistically different for every laboratory. For smoke nicotine the ranking order is the same for all laboratories. All pairs are statistically different in all but three laboratories for which only the 400 mg articles were not statistically different. Ther andR data are given in tables and in graphical representation. The graphs show thatr andR increase with the mean values of NFDPM and smoke nicotine yields. Such a trend has also been found in studies using factory-made cigarettes. A comparison of results shows thatr values for articles are approximately 40% greater andR values about 100% greater. The variability of individual hand-made articles in this study is likely to be much greater than the variability of machine-made matched cigarette samples. The method detailed in ISO 15592-3, therefore, is satisfactory for general adoption even in laboratories where there has been little previous experience.