Technical Report Collaborative Study of CORESTA Ignition Propensity Monitor Test Piece CM IP 2 for the Determination of Ignition Propensity

Transcription

1 Routine Analytical Chemistry Sub-Group Technical Report 2014 Collaborative Study of CORESTA Ignition Propensity Monitor Test Piece CM IP 2 for the Determination of Ignition Propensity March 2015 Co-ordinator: Linda A. Crumpler, Cerulean, USA Study Co-ordinator: Guy Jaccard, PMI, Switzerland Authors: Guy Jaccard and Donatien Tafin Djoko, PMI, Switzerland

2 Table of Contents 1. Introduction Organisation Participants Protocol Raw data Statistical Analysis Results... 8 Appendix A: Mandel s h and k Plots... 9 Appendix B: Distributed Test Protocol RAC-CTR 2014 Collaborative Study CM IP 2 March /13

3 1. Introduction The CORESTA Routine Analytical Chemistry Sub-Group has been given the responsibility to provide a monitor test piece specific for the ignition propensity testing, according to ISO 12863:2010. A candidate CORESTA monitor test piece has been manufactured in the Philip Morris International Neuchâtel (Switzerland) factory in January 2014, with product specifications established on the basis of prototype cigarettes previously analyzed. To assess this product called CORESTA Monitor IP No.2 (CM IP 2), a collaborative test has been organized within the CORESTA Routine Analytical Chemistry Sub-Group. The NIST 1082 reference cigarette has been analyzed as well for comparison purposes. The goal of this report is to present the results of the statistical evaluation performed with the results obtained from the participating laboratories. 2. Organisation 2.1 Participants In total 14 laboratories participated in the collaborative study. The list of laboratories was as follows: Altria Client Services, USA British American Tobacco, Germany British American Tobacco, South Africa Enthalpy Analytical Labs, USA Essentra Scientific Services, UK ITC, India Japan Tobacco, Japan Japan Tobacco International, Germany Landewyck, Luxemburg Philip Morris International, Switzerland Reemtsma Imperial Tobacco Group, Germany Seita Imperial Tobacco Group, France SWM, France Papierfabrik Wattens, Austria RAC-CTR 2014 Collaborative Study CM IP 2 March /13

4 2.2 Protocol Participants were requested to follow the method ISO 12863:2010 with 10 layers of the required filter paper. The number of replicates per brand (CM IP 2 and NIST 1082 reference cigarette) and laboratory was set to 5 on 5 different days. Each ignition propensity test consisted of a sample of 40 cigarettes. The protocol sent to participants is provided in Annex B. CM IP 2 cigarettes were sent to the participants by Philip Morris International, Switzerland. NIST Monitor cigarettes were from each laboratory stock. 3. Raw data Table 1 below lists the results obtained by individual laboratories for the number (n) and the percentage (%) of cigarettes with full length burn (FLB). Table 1: Laboratory CM IP 2 (n FLB) CM IP 2 (% FLB) NIST (n FLB) NIST (% FLB) 1 1; 0; 1; 1; 1 2.5; 0; 2.5; 2.5; 2.5 0; 2; 1; 1; 2 0; 5; 2.5; 2.5; 5 2 0; 1; 1; 2; 0 0; 2.5; 2.5; 5; 0 3; 0; 3; 2; 2 7.5; 0; 7.5; 5; 5 3 1; 3; 1; 2; 3 2.5; 7.5; 2.5; 5; 7.5 No data No data 4 2; 1; 1; 1 5; 2.5, 2.5; 2.5 2; 5; 5; 6 5; 12.5; 12.5; ; 2; 2; 1; 0 2.5; 5; 5; 2.5; 0 3; 3; 4; 2; 2 7.5; 7.5; 10; 5; 5 6 3; 0; 1; 0; 1 7.5; 0; 2.5; 0; 2.5 1; 1; 3; 4; 4 2.5; 2.5; 7.5; 10; ; 2; 0; 0; 0 5; 5; 0; 0; 0 7; 6; 5; 5; ; 15; 12.5; 12.5; 5 8 3; 2; 2; 2; 2 7.5; 5; 5; 5; 5 3; 3; 2; 3; 2 7.5; 7.5; 5; 7.5; 5 9 0; 1; 1; 0; 0 0; 2.5; 2.5; 0; 0 2; 4; 9; 6; 3 5; 10; 22.5; 15; ; 3; 2; 3; 2 2.5; 7.5; 5; 7.5; 5 6; 4; 4; 2; 5 15; 10; 10; 5; ; 3; 2; 4; 4 7.5; 7.5; 5; 10; 10 3; 7; 6; 7; 2 7.5; 17.5; 15; 17.5; ; 1; 2; 1; 0 0; 2.5; 5; 2.5; 0 5; 4; 4; 4; ; 10; 10; 10; ; 0; 0; 1; 0 0; 0; 0; 2.5; 0 5; 1; 4; 3; ; 2.5; 10; 7.5; ; 0; 0; 0; 0 0; 0; 0; 0; 0; 0 5; 5; 5; 5; ; 12.5; 12.5; 12.5; 12.5 One laboratory did not report results for the NIST reference cigarette (laboratory 3). One laboratory reported only 4 replicates for both brands (laboratory 4). The results of laboratory 14 were excluded from the statistical analysis (no variability in data for the single brands). RAC-CTR 2014 Collaborative Study CM IP 2 March /13

5 4. Statistical Analysis Ignition propensity experiments are typical types of proportion-based analysis with a binary response variable: Full Length Burning (FLB) or not. Statistical analysis is performed assuming that the data generating process is binomial. The response variable of each cigarette (FLB or not) is binary, therefore following a Bernoulli distribution. If the probability of FLB on any trial, p is assumed to be constant, then the number of FLB x in n Bernoulli trials has the binomial distribution with parameters n and p, defined as follows P{B = x} = ( n x ) px (1 p) n x x = 0, 1,, n Where B, referred to the number of units fully burned. The sample fraction of FLB, p is defined as the ratio of the number of cigarettes fully burned B to the sample size n: p = B n The distribution properties of random variable p can be obtained from the binomial with mean, μ p = p, and variance, σ p 2 = p (1 p) n In our case we have: n = 40: Number of cigarettes in each experiment r = 5: Number of replicates per laboratory Having fully burned cigarettes in sample i (B i ), the fraction of individual determination of fully burned cigarettes in the ith sample is computed as p i = B i n i = 1, 2,, r The average, p (amongst individual determination) within each laboratory is given by r r i=1 p = i=1 B i r n = p i r RAC-CTR 2014 Collaborative Study CM IP 2 March /13

6 Therefore the within standard deviation, σ jp for a laboratory j is computed as p (1 p ) σ jp = n The Aggregated within standard deviation (repeatability standard deviation), S r is defined as S r = L j=1 σ jp 2 L, j = 1,, L is the number of laboratory participants The between-laboratory standard deviation, S L S L = L (p j p ) 2 j=1 L 1 Where p, is the aggregated proportion of FLB amongst laboratories defined as p = L j=1 p j L, j = 1, 2,, L The corrected between-laboratory standard deviation, S Lc is finally estimated as S Lc = S L 2 S r 2 r The reproducibility standard deviation, S R S R = S 2 Lc + S2 r The repeatability coefficient of variation in percentage, CV r [%] CV r [%] = S r p 100 RAC-CTR 2014 Collaborative Study CM IP 2 March /13

7 The reproducibility coefficient of variation in percentage, CV R [%] CV R [%] = S R p 100 The 95% confidence repeatability limit, r r = 2 2 S r The 95% confidence reproducibility limit, R R = t 0.975, L 1 2 S R Where t 0.975, L 1 is the t distribution quantile of order with L-1 degree of freedom. It is common practice to fix t 0.975, L 1 as equal to 2. The Mandel between consistency statistics, h j is computed as h j = p j p S L The Mandel within consistency statistics, k j is derived as k j = σ jp S r The approach described here is well documented in the statistical and scientific literature. The reader may refer to NIST Technical Note Additional and advanced details on proportion data analysis are deeply covered by Fleiss L. Joseph, et al. in Statistical Methods for rates and Proportions, 3 rd Edition, Wiley. RAC-CTR 2014 Collaborative Study CM IP 2 March /13

8 5. Results The average proportions of FLB, standard deviations and the Mandel h and k statistics by participant and brand (A= CM IP 2, B= NIST) are reported in Tables 3 and 4 in the Appendix. The statistics h and k are illustrated in figures 1 and 2 in the Appendix. Table 2 summarizes the overall statistics of the two test articles in proportion of FLB. The CM IP 2 exhibits a smaller average percent FLB combined with a higher coefficient of variation. The repeatability and reproducibility are in line with previous CORESTA collaborative tests. If used as a monitor test piece with one replicate of 40 cigarettes, and assuming that a range of mean value ± 2S R is acceptable, one can expect values between 0 and 9.3% (or 0 and 4 cigarettes with FLB). For the NIST reference cigarette, values between 0 and 18.9% (0 and 8 cigarettes) would be acceptable. The global mean value and the range for the standard reference material NIST 1082 obtained in this test are not aligned with the values provided in the certificate of analysis of NIST (12.6% ±3.3% in the certificate provided by NIST dated 28 November 2012). Both the NIST and the CM IP 2 contain zero FLB as an acceptable result. Laboratories who obtain a value of zero for CM IP 2 will need to mitigate the issue (e.g. by measuring more replicates). Table 2: Global summary statistics by test article Global Mean [%] Sr SLc SR CVr[%] CVR[%] r R Test Article CM IP NIST 1082 RAC-CTR 2014 Collaborative Study CM IP 2 March /13

9 Appendix A: Mandel s h and k Plots Table 3: Descriptive statistics for CM IP 2 per laboratory. h and k stands for Mandel h and k consistency statistics. The Mandel h critical limits are +/-1.84 and +/ at 95% and 99%, respectively. The Mandel k critical limits are 1.51 and 1.76, at 95% and 99%, respectively. LAB 11 is flagged as outlier at 95% level according to Mandel k statistic (within deviation) and Mandel h statistic (between laboratories) P[%] SD h k LABS. CODE LAB:A LAB:A LAB:A LAB:A LAB:A LAB:A LAB:A LAB:A LAB:A LAB:A LAB:A LAB:A LAB:A 13 Table 4: Descriptive statistics for NIST per laboratory. h and k stands for Mandel h and k consistency statistics. The Mandel h critical limits are +/-1.84 and +/ at 95% and 99%, respectively. The Mandel critical limits are 1.51 and 1.76, at 95% and 99%, respectively. No between/within Labs outlying laboratories are identified according to Mandel h and k statistics P [%] SD h k LABS. CODE LAB:B LAB:B LAB:B LAB:B LAB:B LAB:B LAB:B LAB:B LAB:B LAB:B LAB:B LAB:B 13 RAC-CTR 2014 Collaborative Study CM IP 2 March /13

10 Figure 1: Mandel h (upper plot) and Mandel k (lower plot) statistics of FLB [%] for CM IP 2 monitor cigarette RAC-CTR 2014 Collaborative Study CM IP 2 March /13

11 Figure 2: Mandel h (upper plot) and Mandel k (lower plot) statistics of FLB [%] for NIST monitor cigarette RAC-CTR 2014 Collaborative Study CM IP 2 March /13

12 Appendix B: Distributed Test Protocol Collaborative Test -Ignition Propensity Protocol 1. Objective To assess the variability (inter and intra-laboratory) for the analysis of potential CORESTA IP Monitor No 2, according to ISO method Test coordinator Guy Jaccard Principal Scientist Philip Morris International QA Governance & Scientific Services CH-2000 Neuchâtel Switzerland Tel: +41 (58) Parameters to be measured The parameter to be measured is the ignition propensity, according to the ISO method Table 1: Parameter to be measured Parameter 1 Ignition propensity Number of cigarettes with full length burn % of cigarettes with full length burn 4. Test methods For cigarette testing, we recommend applying the following standard: ISO RAC-CTR 2014 Collaborative Study CM IP 2 March /13

13 5. Test samples Test samples consist of 1 machine-made CORESTA Monitor IP No 2 and the NIST standard. Cigarette samples are provided by PMI Operations/PPQ, except the NIST standard, for which each laboratory shall use its own stock. Please inspect samples upon arrival and contact the test coordinator in case of problems. Table 2. Test cigarettes for the Proficiency Test 6. Schedule Test cigarette MONITOR IP NO.2 NIST STANDARD For a given brand, 1 replicate of 40 cigarettes should be measured in a single test day, for a total of 5 replicates over 5 independent days. There are no constraints concerning the spacing between the days of experiment, however please keep them as close as possible. The study starts in February Each laboratory is free to organize at its will the timeframe during which it performs the study. However, the test results should be sent to PMI Operations/PPQ no later than March 15 th, Reporting of test results The test results should be reported using the Excel file Template for coll test IP_IP No2.xls. The data are to be reported in the Excel template. In addition to IP test specific results, the temperature and relative humidity during the testing shall be reported as well. Results should be sent electronically: To: Guy.Jaccard@pmi.com Cc: Donatien.TafinDjoko@pmi.com RAC-CTR 2014 Collaborative Study CM IP 2 March /13