REPORT
Are Quality and
,
Productivity Compatible in the Analytical Laboratory.
Harry S. Hertz Center for Analytical Chemistry National Bureau of Standards Gaithersburg, Md. 20899
In an era in which quality is a buzzword in all discussions relating to competitiveness and productivity, it behooves the industrial production manager to examine the relationships among quality, competitiveness, and productivity. The issues of cost-effectiveness and customer needs are becoming prime motivators in the industrial environment. In fact, many companies now define quality as "meeting customer needs." In this environment, it becomes necessary to examine the issues of quality and productivity in the analytical laboratory and also to examine the role of quality chemical measurements in overall industrial productivity. These issues are explored in this REPORT. As a result of reflecting on these issues, it is possible to propose a scenario for the future. Although the discussion is somewhat philosophic, I believe the conclusions are inevitable and they provide information about the chemical measurement system of the future. To put a discussion of quality and productivity in context, one must look at characteristics of chemical measurements, current trends in analytical chemistry, and the current state of the This article not subject to U.S. copyright Published 1988 American Chemical Society
practice of quantitative measurement. With these considerations in mind, one can explore factors that influence productivity and plan for the future.
Characteristics of chemical measurements As all analytical chemists know, chemical measurements of manufactured goods, process streams, byproducts, and effluent streams are very complex undertakings. The complexity is evident when considering some of the key characteristics of chemical measurements. These measurements are relative in nature; the end result is only as reliable as the calibration material or the calibration curve used as the quantitative basis. Sampling and related material homogeneity problems affect the accuracy of measurements and the interpretation of results, thereby affecting decisions related to processing, marketing, and disposal of a byproduct. Chemical measurements are multimethod measurements; a given constituent is often measured by various techniques that have different physical bases for measurement and different biases. Particularly at trace levels, chemical measurements are subject to significant interference. Decisions based on unrecognized interferences can have major economic impacts. Finally, today's chemical measure-
ments usually give only partial information. For example, we can analyze for a trace element, but generally we cannot identify the chemical form (i.e., oxidation state, chemical bonding) in which it exists in a complex material. Greater knowledge of material structure-function relationships will make it important to identify speciation as well as the element present.
Current trends in analytical chemistry With these characteristics in mind, let us examine some of today's driving forces in quantitative analytical chemistry that have an impact on the search for quality and, as measurement complexity increases, on rates of productivity. The first driving force is in response to the fact that most chemical measurements yield only partial information. As we become more aware of relationships between speciation and material performance, there will be an increasing demand for maintenance of very complex speciation information in sample work-up and quantitative analysis. A second driving force is revealed in the trend toward measurement of lower and lower concentrations of constituents in very complex samples, which places a great burden on the accuracy and quality of measurement. When one looks at industries such as high-technology composite materials and semi-
ANALYTICAL CHEMISTRY, VOL. 60, NO. 2, JANUARY 15, 1988 · 75 A
Table I. Interlaboratory variability studies System studied
No. of samples
PCBs in oil Se in serum β-carotene in serum Organic pollutants in water Leachates from hazardous wastes**
No. of labs
Variability (CV)
18 27 11
38-64% a
100% (per sample) 35% (grand average) 500%
Note. These round robins are representative of many others that could have been reported. They represent data generated under the auspices of NBS, the International Atomic Energy Agency, ASTM, and the chemical manufacturing industry. a Range of results is 38-100 ng/L. & For each of 9 elements studied, the range of results was a factor of 10.
conductor devices, one sees an increas ing need for site specificity in analyti cal chemistry. It is no longer sufficient to know only the bulk concentration of a trace constituent; one must know whether it is homogeneously distribut ed or, if not, where it is located in a sample (frequently on a micrometer scale). New measurement instrumentation with increasing automation of chemical measurements is rapidly being intro duced. This is a source of danger be cause sample handling and data ma nipulation frequently are not under the chemist's control and are unavailable for review or modification by the chem ist. To compound the problem, person nel untrained in analytical chemistry, who know less and less about the steps involved in the measurements, are fre quently called upon to operate such "black box" instruments. There is an increasing need for longterm retention of data. The ease of ma nipulating and storing large databases makes it possible to compare data on similar samples over time, over dis tance (e.g., at different manufacturing sites), and across international bound aries. The demand on the chemist is to assure that the compositional differ ences noted are real and not based on analytical bias or imprecision. State of the practice Because modern technology tempts us to compare data generated in different laboratories, analytical chemists must provide accurate information. To sub stantiate this point, data on various in terlaboratory round robins are present ed in Table 1.1 will delve into just the first study that is cited (PCBs in oil). In this study conducted by the National Bureau of Standards (NBS), one of the samples not reported in Table I had no Aroclor (PCB mixture) added. NBS analysis showed that no PCBs were present at the limit of detection, yet
9 out of the 18 laboratories reported the presence of PCBs. One laboratory re ported a high value of 113 ppm. A number of conclusions can be drawn about the state of the practice of quantitative chemical analysis, and one can speculate about the underlying causes of variability leading to results such as those shown in Table I. An ob vious conclusion is that the state of the practice is well behind the state of the art. Routine quantitative measure ment (if participation in a round robin can be considered routine measure ment) falls short of the accuracy and precision achievable under the best of circumstances, which would include qualified chemists, time, and good quality assurance practices. Some of the factors contributing to variability are sample-handling procedures, methodology differences among lab oratories, reagent purity and sample contamination, conditions of laborato ry facilities, and lack of available refer ence or calibration materials for stan dardizing relative measurements. Measurement quality and product reliability A majority of the goods manufactured in the United States is in one way or another affected by the chemical anal ysis of feedstocks, intermediates, and final products. The key issue in decid ing on the level of chemical measure ment quality and necessary improve ments in this quality is the relationship between chemical measurement and product reliability. As more is under stood about compositional variability of materials and the effect this has on performance, product reliability will be improved by better chemical measure ment. A few examples of relationships between measurement quality and product reliability from widely varying sectors of the industrial economy dem onstrate the potential benefits of im proved measurement quality.
76 A · ANALYTICAL CHEMISTRY, VOL. 60, NO. 2, JANUARY 15, 1988
• The estimated value of 1985 ship ments of U.S. breakfast cereals was $5.6 billion. In general, vitamins added to breakfast cereals exceed the amounts stated on the packages. This labeling is done for two reasons: to compensate for the degradation of vita mins during the shelf life of the cereal and to compensate for a lack of homo geneity in the distribution of the vita mins and for the variability of subse quent analysis of the nutrient content of the cereals. In a collaborative study conducted several years ago, vitamin C results obtained by 11 food laborato ries were compared (2). The results ranged from 3.8 to 293 mg/100 g. What would be the economic impact of re ducing this variability? How much could be saved by adding fewer vita mins and distributing them more ho mogeneously? • It is known that oxygen causes fail ure of bearing steels. The current ac ceptable level of oxygen in bearing steels is 10 ppm. In a recent round rob in of leading producers and users of bearing steels, a steel was distributed with an actual oxygen concentration of 4 ppm (2). Results of the round robin analysis ranged from 2 to 8 ppm—a range of 400% for this critical constitu ent. What would be the economic im pact on steel processing and on manu factured goods using bearing steel if the oxygen content were more consis tently and accurately determined? • The estimated value of U.S.-man ufactured electronic products in 1986 was $47 billion (approximately 1.2% of the gross national product [GNP]). The rejection rate for U.S.-manufac tured very large-scale integrated cir cuits is sometimes 99% (3). On the oth er hand, for more common integrated circuit devices, the yield frequently must be greater than 90%. It is known that heavy metals ruin device perfor mance. The current allowed level of uranium and thorium in bulk materials for producing these devices is less than 1 ppb. We do not have a measurement capability for determining where ura nium and thorium end up in manufac tured devices. We cannot perform locationally specific analysis at these levels for heavy metals even though these ele ments may be present at significantly higher concentrations on a locational rather than a bulk basis. When analyti cal chemistry can provide such infor mation, product reliability and success rates should improve. In high-technol ogy industries these complex chemical analyses will make the difference in competitiveness and profitability. Economic impact of chemical measurement It is difficult to obtain a good estimate of the impact of chemical measurement on economic productivity. We do know
that manufactured goods represent approximately 40% of the U.S. GNP {4). Furthermore, the anecdotal information provided above indicates some of the ties between chemical measurement and product reliability. Better understanding of this link should help to improve competitiveness and productivity. A conservative estimate of the number of chemical analyses that are repeated in the analytical laboratory today because of suspected contamination, interference, or poor result is 1 in 10. With a conservative estimate of 250 million chemical measurements per day in the United States, at a cost of $50 billion annually, repeat analyses therefore represent 25 million measurements per day at a cost of $5 billion annually. At our current level of sophistication, we cannot fully correlate chemical composition with product performance and functional characteristics. In industries in which chemical composition is already tied to product performance, it has been estimated that as many as 30% of the samples must be retested. If one assumes that this relationship holds constant in the future, the cost of repeat analyses alone would be $15 billion annually or nearly 0.5% of the GNP. A recent estimate for U.S.-manufactured goods indicated that 10-20% of
domestic sales are for "off-spec" products—manufactured goods sold at a loss or reprocessed to meet specifications (5). Because manufactured goods represent 40% of the GNP, off-spec products represent 4-8% of the GNP. Of course, one cannot conclude that chemical analysis would prevent the manufacture of off-spec goods, but by considering the two cases just presented, it can be estimated that between 0.5 and 8% of GNP is directly affected by the quality of chemical measurement. Even 8% is probably a conservative estimate of the overall impact of chemical measurements on U.S. productivity, because the total impact also includes measurements that qualify or reject feedstock and process streams, resulting in high-quality products. Certainly as the state of chemical measurement improves and as relationships between chemical composition and product performance are better understood, the impact of quality chemical measurement on U.S. productivity will increase. Laboratory of the future If one accepts these arguments, one can speculate on how measurements will be made in the laboratory of the future. Laboratory efforts would begin with the accurate measurement of a chemical constituent known to be important
to product performance. The concentration of that constituent would then be varied and the impact on product performance determined. By ascertaining the concentration level at which product performance suffers, one could then set accuracy and precision goals for measuring that constituent in feedstocks, intermediates, and final product. Thus performance characteristics for the product and measurement goals for the chemical and physical testing laboratories could be established simultaneously. Productivity would be maximized both in manufacturing and in the cost-effective quality assurance program in the chemical laboratory. A discussion of measurement in the future would be incomplete without stating that the laboratory of the future will be closer to the actual production process. Developing more sophisticated chemical sensor technology and providing more immediate feedback to the process stream controller will result in greater use of in-process measurements in industry. The laboratory of the future will also have a number of analytical aids now being developed to assist in the generation of quality data and to enhance the productivity of the laboratory. The first major contributors will be expert systems capable of providing informa-
GAIN
WITH AMERICAN • Keep up-to-date with weekly copies of CHEMICAL AND ENGINEERING NEWS • Enjoy substantial discounts on subscriptions to ACS's internationally respected, authoritative journals and publications • Network with your fellow scientists at local, regional and national meetings • Enhance your©areer opportunities with ACS employment services • Save on insurance and retirement plans and tax deferred annuity programs • Discover the latest advances in your discipline with a first-year-free Division membership
. . . and this is just the beginning. 78 A · ANALYTICAL CHEMISTRY, VOL. 60, NO. 2, JANUARY 15, 1988
Learn why 9 out of 10 ACS members renew year after year. Gain the Professional Edge: Join ACS now. For further Information write or send the coupon below or call TOLL FREE 1-800-424-6747 American Chemical Society 1155 Sixteenth St., N.W. Washington, DC 20036 YESI Please send information on the advantages of joining the ACS.
Name Address
I am most interested in the following science(s):
WHEATON
Product performance
VACUUM SOURCES High technology innovations for low pressure performance
. Multivariate ^ correlations
Measurement accuracy
Figure 1. The interaction of quality- and productivity-determining factors
Vacumate™ •
Nonelectric, explosion resistant vacuum pump • Whisper quiet operation with no moving parts Lightweight and portable — operates at 58 psi compressed air A 3 S Aspirator ~ Conserve water— selfcontained recirculating water supply requires no water tap hookup • Compact, safe, and easyto-operate — perform two independent aspirations simultaneously • Constant pressure for stable vacuum over a large displacement volume For more information call toll-free 1-800/225-1437.
WHEATON I N S T R U M E N T S Manufacturers Since 1888 1301 N. Tenth Street Millville, NJ 08332, USA Call Toil-Free: 1-800/225-1437 Ext. 2527
tion on analytical methods and techniques of choice for performing particular analyses. In the long run, expert systems will control the chemical measurement process in the laboratory. Laboratory robots will initially perform chemical manipulations, and then they will obtain instructions from expert systems programmed by analytical chemists. Finally, chemometrics will be fully incorporated into the operation of the analytical laboratory. Using chemometric approaches, data reduction will include feedback loops to a robot performing chemical manipulations or to an expert system controlling the chemical robot and thus will permit fine-tuning of an experiment to improve analytical data. Furthermore, chemometric approaches will be used more heavily in the initial design of experiments to obtain information on as many constituents as possible in a single experiment. The laboratory of the future will be governed by a measurement triangle as shown in Figure 1. All three components will interact to assure accuracy of data and sufficient quality to meet product performance requirements. Given the requirements of measurement accuracy and the product performance, multivariate correlations will be made to show the relationships between different chemical constituents and their impact on product performance. Such correlations will further enhance performance and then dictate any improvements needed for measurement accuracy. It seems logical to conclude that productivity, profitability, and competitiveness will be based on efficient production of high-quality products. Quality products will result from obtaining all information available—both performance- and composition-related. To the extent that compositional information learned early in the manufacturing process can help to avoid manufacture of off-spec products and improve the quality of a product in real time, compositional measurement and the analytical chemist will be vital to industrial productivity.
CIRCLE 177 ON READER SERVICE CARD
80 A · ANALYTICAL CHEMISTRY, VOL. 60, NO. 2, JANUARY 15, 1988
The author gratefully acknowledges many helpful discussions with Curt W. Reimann and Ranee A. Velapoldi during the past several years. Their contributions made it possible to create this paper.
References (1) Egberg, D. C. In Reference Materials for Organic Nutrient Measurement; Margolis, S. A., Ed.; NBS Spec. Publ. 635; U.S. Government Printing Office: Washington, D.C., 1982; pp. 8-12. (2) Diamondstone, B.; Flinchbaugh, D.; Green, W. Proceedings of the International Symposium on Effects of Steel Manufacturing Processes on the Quality of Bearing Steels; American Society for Testing Materials: Philadelphia, Pa., in press. (3). Downing, R. G., personal communication. (4) Statistical Abstract of the United States: 1987,107th éd.; U.S. Government Printing Office: Washington, D.C., 1986; p. 416. (5) Kowalski, B. R., personal communication.
Harry S. Hertz is the director of the Center for Analytical Chemistry at the National Bureau of Standards. He received a B.S. in chemistry from the Polytechnic Institute of Brooklyn (1967) and a Ph.D. in organic chemistry from the Massachusetts Institute of Technology (1971). After spending two years as an Alexander von Humboldt Fellow at the University of Munich, he joined the staff of the National Bureau of Standards. His research has been in the area of organic mass spectrometry, with emphasis on quantitative trace organic analysis. His current interests are in analytical chemical and clinical measurement systems, quality assurance, and future systems for accomplishing quantitative chemical measurements.
