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oaC Accession No. 52-153' Copy No. 1' Issued To -P(,Zq,'Z,{;3 aZ- PHILIP M O R R I S U. S, A, R E S E A R C H C E N T E R CHARGE NO. & TITLE: 1752 CIGARETTE SMOKE STUDIES TYPE REPORT: 0 ANNUAL Q SEMiANNUAL 0 COMPLETION ® SPECIAL BATE' May 12, 1982 REPORT TITLE: PERIOD COVERED: Oct. 1980 - April 1982 CIGARETTESMOKE AND FILTER DILUTION ANALYSIS USING TUNABLE DIODE LASER INFRARED SPECTROSCOPY: I. DESIGN'OF A COMPUTER-CONTROLLED PUFF X PUFF SYSTEM BY MiLton E. Parrish, Charles N. Harward, and'Arthur T. Hill SUPERVISED BY G rs Vilcins ~ APPROVED BY DISTRIBUTION: Dr. R. B. Seligman Dr. M. Hausermann Dr. W A. Farone Mr. L. F. Meyer Dr. T. S. Osdene Dr. R. Fagan Dr. R. M. Ikeda Mr. W. E. Claflin Mr. A. C. Lilly Dr. A. J. Kassman Dr. J. F. Whidby Dr. W. A. Geiszler William F. Kuhn Mr. R. M. Waugh Dr. J. L. Charles Dr. R. W. Jenkins Mr. P. N. Gauvin Mr. W. G. Houck Dr. R. W. Dwyer Mr. R. D. Carpenter Dr. P. Martin Mr. R. M. Wiley Mr. W. T. Belanger Mr. B. D. Jeltema KEYWORDS: Tunable Diode Laser Cigarette Dilution CO Puff X Puff MINC 11/23 Dr. G. H. Bokelman Dr. R. H. Cox Mr. R. E. Davis Mr. W. R. Harvey Dr. J. 0. Lephardt Mr. D. C. Watson Central File (2) Day File (4) l

Table of Contents Page No. ABSTRACT I. OBJECTIVE 1 II. INTRO DUCTION 1 III. OPTIC AL LAYOUT 4 IV. COMPU TERIZED GAS TRANSFER SYSTEM 6 V. ELECTRICAL CONFIGURATION 10 VI. EXPER IMENTAL 14 A. Calibration and Standardization of CO and N20 14 B. Cigarette Information 16 C. Procedure 16 VII'. RESU LTS AND DISCUSSION 23 VIII. CONC LUSION 41 IX. ACKNOWLEGMENTS 43 X. REFERENCES 43 APPENDIX 1 44 APPENDIX II 47 v

ABSTRACT A computer-controlled gas transfer system which is linked to a tunable diode laser(TDL) system is used'to determine the change in filter dilution as a cigarette is smoked. This information can be utilized in the development of new products. The approach we have selected is to place a cigarette with the ventilation holes of the filter in a chamber filled with a gas not found in cigarette smoke, such as nitrous oxide (N20), and to mix this gas with the smoke under actual smoking condi- tions. By judiciously selecting a TDL with the appropriate tuning range, molecular absorption lines for both the N20 and a representative smoke component, such as carbon monoxide (CO), can be located and monitored simultaneously. The N20 provides information concerning the dilution level and the CO provides information about mainstream smoke. Thi~s is the first study of which we are aware that the concentration of CO inevcigarette smoke is obtained along with information about the filter dilu- tion for each puff under dynamic smoking conditions. Experiments were conducted using cigarettes having different filter dilutions. Each cigarette was measured for static dilu- tion prior to smoking using a standard~pressure drop method. The values for 100% N20 absorbance and the N20 absorbance obtained by taking a puff from an unlit ci~garette were determined and used to calculate the percent dilution of the filter. Analysis of the data show that the average dilution for all lit puffs is greater than the di~lution determined for the unlit puff except for the i

very last puff where some of the cigarettes showed a decreased dilution value of 0.5% dilution units. All of the levels measured by the TDL method are higher than the dilution level determined by the static dilution method. The average dilution level for the lit puffs stays relatively constant though there is a slight tendency for the later puffs to drop to the dilution level of the unlit cigarette. ii %W, !

: 1 I. OBJECTIVES This study was initiated to characterize more fully the relationship of filter design and ventilation to the dilution level as the cigarette is smoked. Results from this study will provide information which can be compared to models developed by the Filtration Physics Group. Some of the models developed by that group are designed to predict the relationship between filter ventilation and the level of dilution under actual smoking conditions. In order to meet the above objectives, the initial phase was to design and implement.an experiment incorporating the TDL system and the Digital Electronics Corporation(DEC) MINC Microcomputer to provide accurate data for this investigation. II. INTRODUCTION The quantitation of combustion gases in cigarette smoke can proiride an abundance of information useful in achieving controlled modification of cigarette deliveries. The objective of the work is to determine more clearly the relationship of filter design and ventilation to the dilution level achieved as a cigarette is smoked. This information can be utilized in the development of new products. The investigation was performed with a lead salt tunable diode laser (TDL) emitting in the 4 to 5 micrometer spectral region. The technique used was particularly well suited for the measurement of gases from~ the cigarette because of the high speed, sensitivity, and resolution of the TDL.

2 The technique for measuring the cigarette dilution involved placing the ventilation holes of a cigarette inside a chamber filled with a gas not found in cigarette smoke. When a puff was taken on the cigarette, the gas, in this case, nitrous oxide (N20) was pulled through the ventilation holes and was mixed with the cigarette smoke. The amount of N20 that was present in the mixture is proportional to the dilution of the cigarette. If the operating wavelength of the TDL were judiciously chosen, then a representative smoke component, such as carbon monoxide (CO), can be monitored simultaneously with the N20 pulled through the ventilation holes, with the N20 providing information about the dilution level and the CO providing information about the main- stream smoke. Although cigarette dilution during smoking has been investigated(1), this is the first study of which we are aware that the concentration of CO in the cigarette smoke is obtained along with information about the dilution level: for each puff. This investigation will provide the basis for obtaining a clearer understanding of the complex interaction that filter dilution has on the CO delivery. In order for this investigation to provide accurate and meanful results, special attention had to be focused~on several areas of concern in the experimental design of the TDL and the gas transfer system. The major areas are as follows: 1.) To obtain puff-by-puff results, time constraints required very fast evacuation of the 13 L volume cell. 2.) To mini'~mize contamination from one puff to the next, adequate sequential flushing of the gas handling lines had to be performed. 0

3 C, 3.) To minimize atmospheric contamination and back diffusion of smoke from the cigarette ventilation holes, the system required the design of a dilution chamber with sensitive automatic pressure sensing and control as well as constant flushing. 4.) To control precisely the amount of smoke to be analyzed and. improve reproducibility, a low-dead volume sampling valve had to be incorporated into the gas transfer system. 5.) To perform all of the tasks within the time restraints, the automation of the entire„system was required. 6.) To provide the accuracy and precision needed in this experiment, a microcomputer was chosen to control all aspects of the experiment, thus necessitating the design of a custom interface between the computer and gas transfer system. 7.) Since no software existed to control the experiment, to collect, and analyze the data, computer programs had to be written, debugged, and implemented. 8.) The storage of the data collected from this experiment required a microprocessor with capabilities beyond those of' the MINC 11/03. Thus a larger, faster microcomputer had to be specified, ordered, and delivered to fulfi~ll the exper- imental requirements. 9.) Because the TDL wavelength is a function of its time- history (wavelength hysteresis), special electronic circuitry had to be designed, and specifi'~ed. This report discusses in detail the design chosen for this investigation and examples of the type of data generated.

4 III. OPTICAL LAYOUT A diagram of the optical system based on the Laser Analytics LS-3 spectrometer is shown in Figure 1. The diode laser (#0168-28, Model SP5610-2170, Laser Analytics, Bedford, MA, 01730) which is mounted in a cryogenic closed cycle refrigrator (Model 21,CTI, Waltham, MA, 02154) is collected and collimated by an f/1 KRS-5 lense. This collimated radiation, which ranges in frequency from 2160 to 2190 cm 1, passes through a compartment that houses a reference gas cell and a 75 mm solid Ge etalon. The reference gas cell contains CO and is used to identify the absolute frequency of the TDL radiation from the known positions of the molecular absorption lines of the reference gas. The solid Ge etalon is used to find the frequency of the TDL between the known reference absorption lines. This is necessary since the tuning of the TDL can be highly non-linear. The TDL radiation, after passing through the sample compartment, is focused onto the entrance of a 4.17 m base pathlength Laser Analytics White cell(2). The radia- tion after passing through the cell is focused on the exit aperture of the cell. Transfer optics recollimate the radiation and then focuses the radiation onto the entrance slits of the LS-3 mono- chromator section. The radiation is also mechanically chopped at the entrance slits by a tuning fork chopper (Model L2, American Time Products, Woodside, NY, 11377). This is done because the A.C. detection system requires modulated light. The monochromator is used to isolate a single TDL mode from the multi-mode (multiple N frequency) TDL radiation. The separated mode passes through the ~ Ca exit slits of the monochromator where transfer optics focuses the P_ radiation onto a liquid nitrogen cooled InSb detector. The wo 4~b lob C4

Figure 1 Schematic of Optical Path - TChopper - ~ ~ }Ref. Cel~ t . --,_ ~----- !~ - ------ - _ _----- -_-- - ~ _ t i ~T~ 1 I ~ Etalon ] t -- .~ White Cell -f=- i Grating Detector I V Monochromator i , Interface Optics 9 ~ y i Q L f/1 Lense Three Position Sample Compartment 9i~ES~~zaz ~

6 signal from the InSb detector, which is proportional to the amount of radiation passing through the White cell, is demodulated by a lock-in amplifier (Model 128A, Princeton Applied Research(PAR), Princeton, NJ, 08540) referenced to the tuning fork chopper frequency. The output of the lock-in, which has a one volt maximum value, is offset by one-half volt. Then the output is DC amplified'by a Model 113 preamplifier (PAR) to bring it up to the ± five volt level required by the analog to digital convertor (ADC) on either the MINC 11/03 or DECLAB 11/23 (DEC) microcomputer used to take the data and control,the experiment. The offset and amplification are needed to take advantage of the full dynamic range of the 12 bit ADC. IV. COMPUTERIZED GAS TRANSFER SYSTEM Figure 2 shows the gas transfer system used to sample the cigarette smoke. The dilution chamber in which the cigarette filter is inserted is made of glass and has rubber dental dams which seal the pure N20 obtained from a pure (>99%) N20 tank (Matheson Gas Products, East Rutherford, NJ, 07073). The filter end of the cigarette is inserted through a dental dam so that the ventilation holes are exposed to the N20 in the chamber. The very tip end~ of the filter is inserted into a second dental dam fastened to a glass tube which is supported by a #4 rubber stopper placed in the other end~ of the dilution chamber. The glass tube passes through the stopper and is connected to the input solenoid (A) of a one-port, syringe type smoking machine. This solenoid,, as well as the others, in Figure 2 are indicated by square boxes