Lynn L. Lewis Research Laboratories General Motors Technical Center Warren, Mich. 48090
ANALYTICAL CHEMISTRY AND CONSUMERISM To the consumer, the automotive industry may appear to be like a duck on water—calm, unruffled, and moving forward serenely. But I assure you that there is furious paddling beneath the surface! Amidst all of this vigorous activity, analytical chemistry has vital contributions to make on efforts to conserve materials, solve environmental problems, and ensure product quality. All of these activities require the analysis of chemical systems. Thus, the analytical chemist—a consumer—has direct responsibility in these matters. Today, 9% of personal income in the United States is spent on the automobile (Figure 1). Over two-thirds of all passenger car trips are related to earning a living and family business, and less than one-third is for religious, social, recreational, and other activities (1). On the other side of the coin, some 13 million jobs—one in every six—are created directly or indirectly by this consumerism. An estimated 50,000 firms supply materials, parts, components, and services to motor vehicle manufacturers. Materials Usage. The automobile
industry is properly regarded as a nonchemical industry, but chemistry is here to stay in an industry so heavily dependent on the properties of materials. This is illustrated by the fact that other industries annually produce over $13 billion in automotive parts, with an equally impressive employment (Figure 2). As another measure of materials usage, the average car contains about 15,000 parts. Relationship with Suppliers. When we think of "consumerism" and this industry, we tend to think offhand of the products of personal interest that we see on the highway. This industry is also a consumer, however, with nearly 50% of all revenue going to suppliers of materials and services. Thus, the companies have specifications and test methods for materials purchased and used in their products; in scope, these test methods may range from "ABS Plastics" to "Zinc Plating". In addition, as a consumer the industry has direct interest in at least 39 of the 47 parts of the "1974 Annual Book of ASTM Standards" of the American Society for Testing and Materials.
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With regard to consumer interest in reliable, high-quality products, 35,000 people will spend some 70 million man-hours this year on quality and reliability control in one automotive company alone (2). As an example of the benefit of this effort, the probability of a new car starting on demand is about 0.9995. (This is higher than the reliability of some parts on Apollo missions.) These facts and figures are suitably impressive, but my point in presenting them is to illustrate the fact that analytical chemistry contributions to this industry must include those stemming from all other industries that provide raw materials and parts. Because of the breadth of this subject, most of my references will now be limited to these activities within the automotive industry. Past Efforts Analytical Instrumentation. Analytical instrumentation has a long history of development and application in the automotive industry. For example,'in the late 1920's all three physicists in the General Motors Research
Report
Photograph by Paul McKng iht
IN THE AUTOMOBILE INDUSTRY Laboratories had their PhD degrees in atomic or molecular spectroscopy (3). At that time techniques for purifying hydrocarbons were certainly inadequate, and identification was limited mostly to melting point, boiling point, and refractive index. Thus, one of their early projects was on the development of infrared spectroscopy for the analysis of hydrocarbon mixtures for fuel-engine studies on the knocking characteristics of various gasolines. They also made important contributions to optical emission spectroscopy in the early 1930's; a broad patent (4) was issued that was subsequently licensed to a number of companies without charge, but with a provision for exchange of ideas on method improvements. One of the earliest installations of spectrographic equipment for routine materials analysis was set up in 1934 in an automotive company (5). The dramatic growth of analytical instrumentation in this industry is illustrated by Figure 3. As shown, the use of infrared spectrometers has grown steadily, and they outnumber any other type of analytical instru-
ment. Not shown is the fact that they were outnumbered in the past by optical emission spectrographs, many of which have been replaced by direct reading instruments. Newer techniques, such as atomic absorption spectroscopy and scanning electron microscopy, also have impressive growth curves. In fewer numbers (not shown) are mass, nuclear magnetic resonance, and electron spectrometers. For a complete account of instrumentation used for the analysis of automotive materials, those used by suppliers should be added to those shown in Figure 3. I have no way of estimating the number of all of these instruments, but they surely represent an investment of many millions of dollars. With regard to the purchase and use of these instruments, consumerism (again) has two facets. First, the end use of the instruments is to support efforts on providing products that are satisfactory to the customer. Second, consumerism comes to mind when we purchase an instrument after compar ing competitive instruments on the basis of resolution, sensitivity, versa-
tility, cost, and the like. Perhaps the best tribute to the manufacturers of analytical instrumentation is seen in the widespread and growing use of their equipment in so many areas important to all consumers. Growth of Infrared Spectroscopy. Let us continue by focusing on infrared spectroscopy, one of many analytical techniques used daily in automotive manufacturing plants for receiving inspection. One material inspected is engine oil, which contains antiwear agents, detergent-dispersants, oxidation inhibitors, rust and corrosion inhibitors, viscosity index improvers, and foam inhibitors. To ensure that a "factory fill" oil received from a supplier is the same as that approved after extensive tests in engines and cars, infrared spectra are obtained on shipments to detect deviations in the base oil and additive content. As a matter of direct consumer interest, the recommended interval for oil change has increased from 2,000 miles in 1950, t o two months (or 4,000 miles) in 1962, and to four months (or 6,000 miles) today. A fascinating account (3) of infrared
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Figure 1. Portion of personal income spent on automobiles ( 1)
spectroscopy in an automotive company has been provided by Gerald M. Rassweiler, who collaborated with the pioneering infrared group at the University of Michigan in the late 1920's. After two years of patient and meticulous work, the spectra of 25 compounds were obtained. No relationships could be established between engine knock and the position of absorption bands, but the potential of infrared spectroscopy for hydrocarbon analysis became apparent (6). Later, the first procedures were described for analyzing multicomponent liquid mixtures with concentrations of any of the components varying from 0 to 100% (7). Although all conscionable researchers keep societal benefits of their work in mind, the magnitude of these benefits may only become apparent much later. For example, in 1934 Max D. Liston, an electrical engineer in an automotive research laboratory, worked on the development of thermopiles and breaker-type dc amplifiers for use in infrared detection systems (3). He later joined the Perkin-Elmer Corp. and designed a new double-beam recording spectrometer (8). Subsequently, he formed his own company and developed an infrared nondispersive analyzer for monitoring automotive emissions. This instrument, manufactured by Beckman Instruments, Inc., is now widely used for determining whether exhaust emissions from a car are within prescribed emission limits. Present Applications
To single out a major difference between past and present activities, a major portion of today's effort is placed on examining samples with techniques so sensitive that many of the substances of interest can be found almost anywhere. This is also true elsewhere and applies, for exam-
Figure 2. Other industries annually produce over $13 billion in automotive parts ( 1)
.. - GJS r.hromatixjraphs 3 - ûptîcil omission spectrometers. direct reacting 4 - Atomic absolution spectrometers 5 - X-ray emission spectrometers •:• - Scanning electron microscopes
Figure 3. Growth of analytical instrumentation in automotive industry
pie, to traces of bismuth in steel, mercury in fish, phthalates in plastics, and impurities in semiconductors. Common to all of these examples is the need for complete regard for sampling and the analytical "blank". In some instances, unfortunately, analytical incompetence and premature conclusions have led to undue concern in matters of public interest, and scientific effort has been diverted from genuine problems. In other words, some irresponsible actions remind me of a remark said to have been made by one of the passengers on that famous hydrogen-filled zeppelin that was soon to burst into flames, "I guess we're allowed to smoke." Just as we see today, there was action and reaction!
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Diverse Analytical Competences. A list of the analytical competences required in the industry would be quite extensive. Instead, shown in Table I is a list of research activities that depend on analytical chemistry services. To help the industry respond to the demands of a rapidly advancing society, the dimensions and directions of research programs in these groups change continually. For example, analytical chemistry activities are closely associated today with increased emphasis on environmental science (sources, dispersal, and effects of pollutants), physical chemistry (catalysis), and polymers (aging effects and recycling).
T a b l e 1. R e s e a r c h G r o u p s T h a t R e q u i r e A n ;ilytical C h e m i s t r y Services Biotiii Electr ochomistry ;
':;Ί.;::·. ·Ξ~Γ'·Ζ~ ion·; research
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Oil Consumption Measurements of Engines. Requirements for materi als, parts, and components are set forth in specifications to be met by suppliers. These separate specifica tions alone, however, do not guarantee the overall quality of the manufac tured unit. Thus, reliable methods that test product performance are continually being developed and ap plied. As an example, product quality was improved by detecting and cor recting the cause of excessive oil con sumption in some automotive engines on the assembly line. Although oil consumption has been measured by using a calibrated dipstick and a drain-and-weigh method, neither one is fast or accurate enough for in-plant measurements. A radiometric method (9) was de veloped that requires only a few min utes of engine running time to obtain an accurate measurement. In this method (Figure 4) oil containing a small amount of a radioactive bromine compound is added to the engine crankcase fill. As crankcase oil enters the combustion chamber during en gine operation, the radioactive tracer is converted to hydrogen bromide and carried out with the exhaust gases. The exhaust gases are passed through canisters where the bromide is cap tured on porous pellets saturated with a sodium hydroxide solution. The amount of radioactivity collected in the canisters is proportional to the rate of engine oil consumption. Fifteen microcuries of bromine (an exempt quantity pursuant to AEC regula tions) are used, which provides the sensitivity for detecting the consump tion of 1 quart of oil in 60,000 miles of vehicle operation. As another benefit, known defects (such as installing a compression ring upside down) can be introduced to measure their effect on oil consumption. Particle Size Measurements. The particle size analysis of colloidal or particulate matter is important in sev870A
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Figure 4. Construction and location of canister (insert) used to trap radioactive bro mine in measuring oil consumption of engines (9)
Figure 5. Optical system of laser light-scattering photometer (10)
eral areas of interest: paints and pig ments, reinforcing fillers for elasto mers and plastics, synthetic and natu ral latex, and pollution studies. Lowangle light scattering (forward lobe) is a particularly useful technique for these particle size analyses in the size range of about 0.05-50 μηι. To take full advantage of this technique, an in strument was designed that features the use of lasers for high angular reso lution, a single photon-counting sys tem for providing precise digital data, 46,
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and an automated data collection and treatment system (10). A schematic of the optical system is shown in Figure 5. Measurements in situ are provided, thus avoiding some of the inherent problems of measurements by micros copy. The method is independent of concentration over a wide range, rath er insensitive to particle shape differ ences, and largely independent of re fractive index. In one application the instrument was applied to latex rubber matura-
tion studies (27.). Basic information was provided on the relationship be tween processing variables and the physical-chemical changes occurring during the precure stage. Elemental Analysis of Atmo spheric Aerosols. Measurement of daily variations of individual elements in the atmosphere can be used to de termine the sources of pollution. Fil ters of small pore size (
