Environmental Fears Fuel Growth In Chemical Standards

The need for chemical standards is skyrocketing, as a health-conscious public clamors to learn exactly how many parts-per-billion of pesticides are in their veggies, PCBs in their fish, dioxins in their milk, antibiotics in their burgers, cholesterol in their blood, and drugs in their employees' urine. But like a diner unable to judge the quality of a French restaurant because she's never sampled the finest French cuisine, analytical chemists charged with the mounting demand to establish trace components need yardsticks by which to measure their presence. Helping to meet this demand is the United States Department of Commerce's National Institute of Standards and Technology (NIST), and about 30 private vendors. For these vendors, a booming business in standard materials has emerged because NIST is unable to supply everything; moreover, not everyone needs the utmost precision that NIST applies. The standards business has its share of controversy. Recently, the Environmental Protection Agency ceased giving away chemical standards for some of its pollution-monitoring tests. The termination of this giveaway program touched off a lawsuit by one vendor. The firm says its business was damaged when EPA cleaned out its stocks of standards and provided them for free to five other companies. Standards Everywhere Until 1988 NIST, based in Gaithersburg, Md., was known as the National Bureau of Standards. Selling "standard reference materials," or SRMs, is part of its charge. These are materials whose physical or chemical properties are certified to be present in a certain proportion in a sample, to very high accuracy. NIST's more than 1,100 SRMs are grouped in areas such as agriculture and food sciences, geology, coatings, semiconductors, polymers, environmental and clinical testing, and others. CHEMICAL STANDARDS CONTINUE THE ANCIENT PRACTICE OF MEASURING In days past, people measured things with what they had at hand--literally. Volume was assessed by the number of countable objects that filled a vessel, weight by the number of objects that balanced another. What we now call a carat derives from a carob seed, and shoemakers still use the barleycorn as a unit of measure--it is equivalent to about a third of an inch. Thumbs, big toes, and feet have been prominent in measuring systems. The Saxon term "girth" comes from the circumference of the measurer's waist, a standard obviously prone to great variation. Precision of measurements has come quite a way since King Henry I defined a yard as the distance from the tip of his nose to the end of his thumb. Consider the meter. Until four years ago, the National Institute of Standards and Technology (NIST) defined a meter as the wavelength corresponding to a certain frequency of light emanating from a flow discharge lamp lit with krypton. But even that measuring stick was recently improved upon. "The definition is no longer a wavelength of light, but how far a photon of light travels in a certain amount of time, an infinitesimally split second," says Stan Rasberry, director of measurement services at NIST. He says measuring length in terms of time, which can be measured with extreme accuracy, is considered more precise. Among the most interesting NIST standard materials offered are in the marine realm. An environmental researcher can order freeze-dried sediment from the Buffalo River (with certified amounts of 25 elements), albacore tuna extract (with certified amounts of arsenic, mercury, lead, and zinc), bovine liver (with 27 certified elements), or cod liver oil (with quantified levels of PCBs). Columbia River sediment is available as a standard against which to measure nuclear reactor pollution, containing certified amounts of plutonium isotopes originating from the Hanford Nuclear Reservation in Washington state. At the other end of the pollution spectrum is pristine Peruvian soil, used as a blank against which to spot background radiation or laboratory contamination. The same substance will show up in samples in several NIST areas if it affects society in different contexts. Consider lead. "If you poke around the catalog, you find that lead is offered in powdered paint to help in environmental analysis of peeling paint, in blood to help clinical laboratories check lead levels in children's blood, and in a standard to help labs check lead as a toxin in urine," says Stan Rasberry, director of measurement services at NIST, which includes the SRM program. Lead is also impregnated in filter paper, for use in measuring lead particulates in the air in workplaces. In addition, lead is available in various solutions for calibrating different types of spectrometers. Setting The Standard Scientists consult NIST lists when their work requires the greatest accuracy, which NIST can ensure because it has resources to analyze standard materials in multiple ways, beyond the means of some companies. Although NIST is a nonprofit concern, its extensive testing is reflected in its prices, which are the same as or higher than those of private vendors. The analyses used to chemically characterize a potential SRM complement each other--they are independent, with different sources of error, so they essentially cover each other's tracks. The first step is isotope dilution mass spectroscopy, says Rasberry. That is, a known amount of one isotope is added to a sample as a reference. Then the total amount of each isotope of the element is measured via mass spectrometry, and the amount of change in the ratio between the isotopes tells with great precision how much of each isotope is present in the undiluted sample. "Then we look at a method based on the outer electron shells, such as atomic absorption spectroscopy, followed by a technique based on the inner electron shells, such as X-ray fluorescence analysis. Then we use neutron activation analysis, which doesn't affect the inner or outer electrons, but is nuclear-related," Rasberry says. "If the inner electron, outer electron, and nuclear-based methods give the same results, then we certify the material. That and isotope dilution mass spec, together, give us a lot of confidence," he says. Private vendors often fashion their products using NIST SRMs as models, creating what Rasberry calls a "hierarchical progression of distribution." The relationship is cooperative, rather than competitive, he says. Rasberry offers the example of meter bars, structures used to accurately measure a meter (see accompanying story): "A company makes 10,000 one-meter bars, and says they are traceable to NIST with a slightly lower degree of accuracy. We manufacture one-meter bars to 1-part-per-million [millionth-of-a-meter] accuracy. Say the customer needs 1 part per 10,000. The company transfers our work to 1 in 100,000, and that satisfies the customer. This saves us from having to measure every meter bar in the country, when the customer doesn't really need our degree of accuracy. If you need the highest accuracy, you need [NIST's] ultimate standard, but if not, you can calibrate from a `junior,' or `offspring,' material. It is okay to do this, provided the customer realizes they are losing a little bit of the accuracy in a step-down." Check The Claims Claims of traceability to NIST must be checked carefully, says Eileen Skelly-Frame, a staff chemist in the elemental analysis laboratory at General Electric Corp.'s Research and Development Center in Schenectady, N.Y. She says some companies say a product is "traceable to NIST," implying that some sort of rigorous analytical comparison has been made between their chemical or a standard solution containing the chemical and an original NIST standard. In fact, very often they have simply calibrated their own analytical balances with NIST standard weights, or even weights that have been compared with NIST weights, before preparing their own standard solutions, she says. Analytical Products Group Inc. of Belpre, Ohio, takes a novel approach to ensuring purity. Through its "performance evaluation program," the company allows customers to compare their instruments' analyses on a blind sample with other laboratories' results on the same sample. "APG operates the only interlaboratory performance evaluation program in the country. Currently, over 700 labs in the United States and Canada participate," says customer service representative Myra Rine. Standards Supplier Sues EPA But all is not peaceful in the standards camp. Chem Service Inc. of West Chester, Pa., one of the largest suppliers, filed suit in mid-February in United States District Court in eastern Pennsylvania against EPA, because the agency recently gave away its 800,000 stored chemical standards to five chemical manufacturers, of which Chem Service was not one, under a cooperative research and development (CRADA) agreement designed to foster technology transfer. These companies can now sell the samples, bearing the label "EPA Certified," and EPA receives royalties on sales. The chemicals are typically used to calibrate instrumentation used in EPA-required pollution tests. The samples had been stored for years, and are not of great quality, sources at Chem Service say. "What has happened is that EPA has found a way to help support their research program. They couldn't support their repository, so they dissolved it, and gave out [the samples] under the guise of the Technology Transfer Act. Essentially, they are marketing very-poor-quality products as EPA standards. These samples were never tested to be standard reference materials. But you put an EPA label on it, and everyone thinks it's a great product," says Edward Hollenbach, president of Chem Service. EPA officials acknowledge having received the complaint, but decline comment on the case before their response is filed, which had not yet occurred at press time. Choosing New Standards NIST handles the flood of requests for new SRMs by prioritizing. "We try to further those that are the most useful and that will help the most people do the best work," says Rasberry. One new SRM, for example, is an asbestos particulate material for EPA's asbestos testing program. Practical matters enter into the decision to make a new SRM. NIST must be able to obtain a large quantity of the requested material at an affordable price, and be assured that a market will exist for the eventual standard. "It isn't as simple as someone in industry deciding, `We must have a standard for this--make it!' There is a lot of interaction between NIST, industry, and federal regulatory agencies, so that they can direct their efforts," says GE's Skelly-Frame. This triage system for new SRMs means that some requested materials aren't made. When NIST or a standards manufacturer cannot supply a particular material, a company will generally make its own, by taking part of a typical large batch and analyzing it in several complementary ways, then using it as a standard against which future runs are matched. The Private Sector Vendors supplying standard reference materials tend to specialize. SPEX Industries Inc., based in Edison, N.J., for example, sells inorganic materials, offering 70 different elements available in 500-milliliter bottles at 1,000- to 10,000-parts-per-million concentrations, at prices ranging from $60 to $450, depending upon the element. Purities range from 99.99 to 99.9999 percent, and the products are targeted to plasma emission spectroscopy, a method used to identify elements by heating them to the point at which electrons are stripped from atoms. Ultrapure standards are a must for correctly identifying elements with this technique. A more down-to-earth application of SPEX's inorganic standards is in wear metal analysis, used to pinpoint trouble spots in vehicles. For these analyses, SPEX sells single metals or metals in combinations, suspended in oil, against which an engineer or mechanic can compare oil dripping from a vehicle to help diagnose the problem. For example, chromium in oil points to a defect in rings or valves, copper reflects a bearing problem, leaking iron implicates the engine shaft, lead comes from paint, and sodium metal signals an antifreeze leak. Researchers whose needs are food-related might want to peruse the menu of Crescent Chemical Co. Inc. of Hauppauge, N.Y., which carries hundreds of pesticides and PCBs, and dozens of antibiotics, hormones, and dioxins. Most materials sell for $60 a gram. Some standards are packaged for specific EPA tests. Crescent specializes in lipid analysis standards, selling mixtures of fatty acids that correspond to natural products, such as linseed, olive, poppy seed and soybean oils; lard; and beef tallow. PCR Inc. of Gainesville, Fla., has carved out a niche in supplying organofluorine and organosilane compounds--more than 900 of the former, used to synthesize coatings, and more than 260 of the latter, used to synthesize plastics, oils, and medical implants. The materials may be used as standards, as most are 97 percent to 99 percent pure. "We do have some products that are used routinely for mass spectrometry calibrations. We supply manufacturers of mass spec instruments, and they give the standards to their customers," says Rick DuBoisson, business manager of research chemicals at PCR. Of the nine materials in a mass spec "kit," five are fluorine-based compounds available only from PCR. The company also supplies standards for gas chromatography, used for environmental analyses. Alphagaz, a division of Liquid Air Corp., in Walnut Creek, Calif., bills itself as the "world's major producer of rare gases," supplying specialty gases, including some eclectic standard materials, to "every conceivable industry," says spokesman David Marley. For example, Alphagaz offers a choice of gas mixtures containing traces of volatile organic compounds used in indoor and outdoor air pollution testing, such as benzene, chloroform, toluene, and vinyl chloride, and can also customize blends of sulfur dioxide, carbon dioxide, and carbon monoxide. Its natural gas reference standards include a variety of hydrocarbon mixtures, designed for testing in a gas chromatograph. The company's proprietary computer program assesses optimal pressures for a gas mixture's components to keep the product in one phase, avoiding the common problem of a single component of a gas mixture that condenses onto the cylinder walls and throws off the expected concentration. Standard Reference Materials Simply having a well-characterized standard reference material is of little value if a researcher does not know how to use it. This is where the Philadelphia-based American Society for Testing and Materials (ASTM) comes in. Through this nonprofit organization, scientists teach each other how to use standards to make the most of their equipment. "We are basically a standards development organization. We have 134 different technical committees that bring people together with different interests to produce standards," says spokesman Steve Mawn. Standards at ASTM are not the chemical entities they are at NIST, but are documents telling how to do a particular procedure, or exactly what components should constitute a material. Since 1984, ASTM has run standards technology training courses, at which "standards users roll up their sleeves and get down to work in courses lasting from one to five days," according to Barbara Schindler, editor-in-chief of Standardization News, ASTM's monthly magazine. A recent course on spectrochemical analysis, for example, focused on planning and operating an analytical chemistry laboratory, how to calibrate the instrumentation, and how to recognize variant analytical results. ASTM courses are held throughout the United States and generally cost from $400 to $700. Ricki Lewis teaches biology at the State University of New York, Albany.

Environmental Fears Fuel Growth In Chemical Standards

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