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November 28, 1975 Preliminary Draft Proposal for Research SRI No. 8LH DEVELOPMENT OF PORTABLE ANALYTICAL INSTRUMENTATION Prepared by: Edward M. Liston, Senior Chemical Engineer Atmospheric Sciences Laboratory Electronics and Radio Sciences Division Milton B. Adams, Manager, Digital Development Dale M. Coulson, Manager, Inorganic Physical Chemistry Approved by: Ray L. Leadabrand, Executive Director Electronics and!Radio Sciences Division Bonnar Cox, Executive Director Information Science and Engineering.Division C. J. Cook, Executive Director Physical Sciences'Division

INTRODUCTION Stanford Research.Institute has been requested to submit a proposal for the development of an unobtrusive instrument package for the analysis of atmospheric carbon monoxide (CO) and nicotine. This instrument system is to.be easily portable, self-contained, and operable by personnel with a minimum of training: A prime requirement for the instrument system is that the data obtained be credible beyond reasonable criticism. Recently a number of studies have been published in which the concentrations of CO and nicotine were measured in public and semi- public places. These data were interpreted in'terms of exposure of the nonsmoker to cigarette smoke. In some cases the data were extended to include the effect of this exposure on the nonsmoker. The initial phase of this research program will focus on the development, testing, evaluation, and verification of the accuracy of an instrument system to measure CO and nicotine under realistic condi- tions. During a future phase two or more of these instrument packages will be assembled and used to survey actual field concentrations in a number of public and semi-public places. The instrument system must be unobtrusive to produce unbiasEd measurements of the individual exposure to cigarette smoke. For example, measurements made surreptitiously would avoid situations where people -~ Q (smokers or nonsmokers) would group around the instrument to observe its d 0 operation. Such grouping could bias the data. T~) Carbon monoxide and nicotine have been chosen as the materials for d analysis. They have been used in past studies because they represent ~ 1

fairly specific trace materials for the gas and particulate phases of cigarette smoke. Carbon monoxide is very stable in the atmosphere and is the second largest gas-phase constituent of cigarette smoke. It is reported that there is an 80 percent correlation between CO and the particulate phase of cigarette smoke. Nicotine is also stable in the atmosphere. It is the largest identifiable constituent of the particulate phase of cigarette smoke. In almost all locations measured concentrations of nicotine can be specifically traced to tobacco smoke--the only other major source being pesticide sprays. It is reported that there is a 95 percent correla- tion between nicotine and the particulate phase of cigarette smoke. Temperature andrelative humidity measurements will provide supplementary data that will be helpful in the interpretation of nicotine concentration data as a function of residence times, stability, CO concentration, and possibly total particulate matter. INSTRUMENT SYSTEM SPECIFICATIONS The following list of specifications is based on our understanding of the client's performance requirements and needs for this instrument system. The Institute will be glad to discuss any specific modifica- tions or changes in performance specifications upon the request of the client. The primary use of this instrument system will be as a research tool to obtain unimpeachable data on the concentration of CO and nicotine at realistic sampling locations within public and~~semi-public places. The system will measure four variables: temperature, relative humidity, Co 2

concentrations in real time, and nicotine concentrations averaged over a short sampling period. The specific methods for performing each of these measurements will be discussed in detail in the following sections. The system will utilize commerci$lly available components and subsystems as much as is practical. It is not anticipated that it will be necessary to undertake any major instrument development efforts during this program. The overall systems specification are as follows: 1. Specificity The specificity for CO and nicotine will be documented on a technical and a statistical basis. 2. Accuracy Temperature: ±0.5oF Relative Humidity: ±57a CO: ±107a or better Nicotine: ±20% with a goal of ±10% 3. Measurement Limits Temperature: 40-110oF Relative Humidity: 5-95% CO: 1-10&ppm(volume) Nicotine: 1-100 ug/ri3' '! ~ t 4. Speed of Respons e Temperature: One minute Relative Humidity: One minute C0: Ten seconds Nicotine: Five-ten minutes collection time, depending upon instrument design. 5. Sampling Location To be determined. This will depend on precedent and'our assessment of what is realistic and 'practical. 6. S=plinQ Time A minimum of one hour on internal batteries. 3

7. Data Recording To be determined. 'Phis.will depend on the amount of testing to be done. It must be determined whether it is more efficient to do the data reduction "by hand" or to make the initial data recording computer compatible. 8. ExternaL Noise Sufficient sound isolation on the sampling pump to make the system unobtrusive in a normal restaurant or similar environ- ment. 9. Size Equivalent to a small suitcase. 10. We iaht One hundred pounds, maximum. 11. Power Source 110 v AC and internal batteries. TEMPEHr'1TURE MEASUREMENT The temperature of the air sample will be measuredusing a small thermistor. The electrical resistance of a thermistor varies in a predictable fashion as a function of temperature. The sensor will probably be placed in the sample air stream to the CO analyzer. Thermistors are safe, rugged, and reliable, and can measure ambient air temperature with an accuracy of ±0.5°F. The output signal from thermistor circuitry is a voltage propor- ~ ~ tional to the temperature of the thermistor bead and the voltage of the C~ power supply. This voltage is amenable to either analog recording or ~ C+7 to conversion to dioital recording. ~ All components for the temperature measurement are commercially ~ available. 4

RELATIVE H[JAIIDITY MEASUREMENT The relative humidity of the air will be measured using, a small solid-state sensor. There are a number of these sensors available commercially. The active element is generally a chemically treated polymer film. The film resistivity changes as the amount of water adsorbed or absorbed in the film changes in equalibrium with~ the atmospheric water. These sensors are safe, rugged, and reliable; especially in this application where the air will be filtered before contact with the sensor. Filtering will remove particles that could impact on the sensor surface and change the calibration. With proper calibration and correction for temperature effects, these sensors can measure relative humidity to an accuracy of ±5 percent or better. The output signal from the sensor is a voltage inversely propor- tional to the relative humidity. It can be recorded in the same way as the temperature signal. NICOTINE MEASUREMENT Measurement Limit A preliminary review of the literature indicates that nicotine concentrations rang~e from 0.7 to 35 µg/Di3 in public and semi-public places. For the purposes of this proposal it has been assumed that the maximum nicotine concentration that will be encountered is 100!p,o/M3. It was also assumed that the system should be able to measure 1 u.g[PM3 of nicotine with an accuracy of ±20 percent or better. 5

Direct Measurement of Nicotine in Air While the meLtino point of nicotine is -80°C, its boiling point is 247°C. Therefore, it is expected that the vapor pressure of nicotine at ambient temperatures will'be so low that any direct measurement in the vapor phase would not be possible. A survey of the literature indicates that essentially all of the nicotine is present in the particulate phase of tobacco smoke. The only feasible direct method of measuring the nicotine concentration of smoke particles is through the use of some form of spectroscopic analysis, probably infrared. It is theoretically possible that an instrument could be developed to analyze individual smoke particles for nicotine. However, such an instrument has not been constructed to our knowledge, and, if it were, it probably would not be portable. In addition, the presence of tars in the smoke particle will make the individual particles optically dense with littTe penetration of the analyzing radiation. Therefore, we conclude that while real time detection of nicotine in smoke particles may be possible, it is probably not a practical method to pursue in this study. Sampling of Air Based on the premise that direct measurement of nicotine in the air is beyond the scope of this research programy the logical approach is to ~ collect samples of particulate and return the samples to the laboratory Q for analysis. The most practical collection method is by use of a filter. Several types of filters are available--mixed cellulose ester, glass fiber, nuclepore, and others. An appropriate filter medium will be selected based on nicotine stability, locations. ~~ j 1. i " ~_,Aj 4; ~ ~ ~- ~ .41 ~ ~ sample flow rate, and sampling uv;1;. ; ? ~ -'iI. . , /~t,(, i ~ ~~~ " Y j f

Filter materials can be used in individual filter holders, in rotary filter wheels, or as a tape in automatic sequence samplers. The best form of sampler will be determined during the development program. Our present feeling is that the individual filter holder mounted or worn at shoulder level will give the most realistic sampling location and wi1L be adequate for the test program. It is expected that the required sampling time will be about 5-10 minutes, depending on the smoke concentration and on the analytical method. The analytical method will determine the total amount of nicotine that was collected. To convert this to an atmospheric concentration it will be necessary to know the total volume of air sampled. Provisions will be made for determining this.,.either through the use of a total flow meter or a flow rate meter with an internal time standard on the data record. Particulate collection devices other than filters are available that utilize the principle of electrostatic precipitation of particles on a: liquid surface. These devices can handle very large volumes of air and have an air/liquid volume ratio in excess of 1,000,000:1.' This type of device could be used to make measurements in areas where there is very low nicotine concentration. However, they are more difficult to use in field tests than filter papers because of the problems of handling liquids. We do not intend to evaluate the liquid collectors during this program unless the clients specifically requires the capability of measuring nicotine at very low concentrations in a short period of time. l

ANALYTICAL METHODS General In this proposed research, an accurate, specific analysis technique is required to determine the concentration of nicotine in the presence of unknown interferences. In general, the system should avoid the requirement for extensive equipment or esoteric techniques that would not normally be available in a modern analytical laboratory. A preliminary review of the literature and discussions with SRI personnel have led to the conclusion that there is nothing sufficiently unique about nicotine chemistry to permit specific measurement without prior separation or concentration from gross samples taken from a polluted atmosphere. There are a number of ways that this separation could be performed. These will be discussed in the following sections. All of these separation techniques require sample handling that would not be practical to perfor6in a small, portable, unobtrusive package. Therefore, it will be necessary to collect the smoke on a filter and then return these filters to a laboratory for analysis. This means that the nicotine concentration will not be determine&in real time, but at the current state-of-the-art, it is the only way that unimpeachable concentration data can be obtained for this compound. It is expected that the filters would.be returned to the laboratory, extracted, and analyzed. A preliminary review of literature shows that many different solvents have been used for this extraction (e.g., water, benzene-chloroform, isopropyl, alcohol, etc.). One reference claims thzt precision of this extraction is ±3 percent. One of the factors that will have to be evaluated during the test program is the optimum~ procedure to use for this extraction. It is expected that an easily identifiable internal standard will be utilized during the extraction procedure. This will allow correction 8

of the final calculated~nicotine values back to the initial amount of- nicotine collected on the filter. Gas Chromatography with Electrolytic Conductivity Detector Gas chromatography is the most commonly used technique for the separation of the type of mixtures that are expected from these samples. The literature shows that many different types of columns, operating conditions, and detectors have been used by others to measure nicotine. SRI has had direct experience in the measurement of both nicotine in rat brains and caffeine. During this work chromatographic techniques have been developed that do an excellent job of separating these types of materials. In order to further improve,the specificity for nicotine and to discriminate against most of the interferences, we propose to use a gas chromatograph equipped with a nitrogen-specific electrolytic conductivity detector. This detector was invented by Dr. Coulson of SRI. The effluent stream from the gas chromatooraphic column is delivered into a high temperature microtube furnace which is fitted with a quartz tube in which the components eluted from the column are hydrogenated over a hot nickel catalyst. The products of hydrogenation are contacted~ with an acid adsorption packing which removes H2S and hydrogen halides. The resulting gas stream containing NH3 from the hydrogenation of the organic nitrogen is then passed through an electrolytic conductivity detector cell. This detection system is insensitive to aliphatic and aromatic hydrocarbons, ketones, alcohols, and sulfur-phosphorus- and halogen-containing compounds. This detector gives equal response of al]l types of organic nitrogen and is sensitive to as little as one nanogram of organic nitrogen. For the proper operation of this system, it is necessary to have about 100 ng of nicotine extracted from the filter. At a concentration 9