Engineering technician James Suddueth (standing) and Research Associate Robert Miller prepare to analyze gaseous Standard Reference Materials using a computer-operated gas analysis system developed at NBS. At right,

an SRM for comparison. But measurement of PAH's poses special problems. First, their low solubility in water makes it impossible to use the more traditional techniques for preparing accurate chemical measurement standards. In conventional standards, known quantities of the chemicals to be measured are typically dissolved in a solution, which is then analyzed and can be packaged for use in calibrating laboratory equipment, evaluating samples, or performing research. But when PAH's are placed in water, they tend to adsorb onto the walls of storage vessels and tubing of the laboratory equipment. Moreover, since they are carcinogenic, they are dangerous to handle. This means that special care needs to be taken in working with these chemicals so that they do not enter the laboratory environment.

Scientists in the NBS Center for Analytical Chemistry and the Center for Thermodynamics and Molecular Science last year discovered a way to overcome these difficulties. Glass beads coated with PAH's were packed in short stainless steel tubes. Saturated solutions of PAH's were first generated by pumping water through a tube and were then analyzed, enabling NBS to certify the stainless steel tube and its contents as a new SRM. The generation of small quantities of known concentrations of PAH's within the tube ensures instrument calibration while limiting both environmental contamination and exposure to the laboratory analyst.

The full significance of this development goes far beyond the provision of an SRM for polynuclear aromatic hydrocarbons. As part of the Bureau's work in a special national program of research about the environmental implications of energy production and use, this technique now

opens the door to the generation of SRM's for the whole range of toxic organic chemicals found in water. For instance, the method also may be applicable to the measurement of pesticide compounds that are otherwise difficult or impossible to measure.

Also in the quest to provide more precise measurements of environmental contaminants in water, NBS last year developed SRM 1643, Trace Elements in Water. This SRM is already helping State environmental and public health scientists to evaluate the accuracy of trace element measurements in filtered and acidified fresh water. It also is useful for calibrating instrumentation used in making these de

terminations. The SRM was prepared using high purity water and 23 elements to simulate the elemental composition of natural fresh water. The Environmental Protection Agency (EPA) has set maximum contaminant levels for a number of the elements contained in the SRM under authority provided by the Safe Drinking Water Act enacted in 1974.

The potential for using new electrochemical techniques to reveal in more detail how toxic chemicals travel through our environment was vividly demonstrated last year in the Center for Analytical Chemistry. Bureau scientists working in cooperation with the University of Maryland coupled two

traditional yet separate techniques used by chemists-liquid chromatography and differential pulse electrochemical detection-to identify and measure methylmercury, a toxic organometallic substance. Conventional analytical methods can be used to measure the total mercury content in an environmental sample, but it is the organometallic mercury species which are deemed most harmful. This NBSapplied hybrid technique allows laboratory researchers to determine selectively the toxic forms of mercury. Bureau scientists used this method during FY 1978 to measure the methylmercury levels in tuna and shark

meat.

On Land, in the Air

The Bureau's environmental research and measurement programs also address the problems of pollutants on land and in the atmosphere. In FY 1978, for example, the Center for Materials Science devised a new method to separate and measure individual organic derivatives of tin and arsenic at trace concentrations in soil as well as in water. These derivatives often are contained in herbicides, antifoulants

(like those used to slow the growth of barnacles on hulls of ships), and a variety of pesticides. By combining traditional chemical separation and detection techniques-liquid chromatography with graphite furnace atomic absorption or with an ultraviolet detection technique-NBS researchers demonstrated a vastly improved method for analyzing metal-based biocides in the environment.

This Bureau innovation permits the measurement and characterization of individual elements in the parts-perbillion range and provides greater sensitivity than conventional measurement methods. It also allows quicker evaluations and does less damage to the sample being analyzed, which means that the sample can be used again for other tests. With this method, researchers can follow the progress of these materials as they degrade, are transported, and concentrate in parts of the environment. They can also observe the transformation of what may be a relatively harmless herbicide, for instance, into a toxic or carcinogenic form.

The first phase of another Bureau project important for safeguarding both

land and water resources was completed in FY 1978 when NBS researchers developed test procedures which can be used to compare recycled oils with "new" (virgin) oils. This effort by the Office of Recycled Materials will encourage the reuse of once-used oil which would otherwise be wasted or possibly become a serious environmental hazard if dumped into sewers, rivers, or landfills. The NBS test procedures were called for in the Energy Policy and Conservation Act enacted in 1975 and are to be used to establish the "substantial equivalency" of recycled oil with virgin oil for each potential end use. The Bureau's test procedures are being provided to the Federal Trade Commission, which will then remove certain restrictive labeling requirements for recycled oils that can pass the tests. This should enable recycled oils to compete more effectively with virgin oils in the marketplace.

The Bureau's measurement capabilities are also applied in controlling air pollution from automobile exhausts and achieving Federal clean air standards. And since auto fuel economy ratings are calculated on the basis of exhaust gas measurements, NBS measurement skills are also important in this facet of Federal automobile standards concern. Along these lines, several advancements in auto exhaust analysis were made in FY 1978 at the Bureau, which has been providing SRM's and performing research in both automobile fuel economy and pollution measurements for a number of years. Through an agreement signed last year, the Bureau is assisted in its development and production of SRM's in this area by a 2-year Research Associate Program sponsored by the Motor Vehicle Manufacturers Association. The program aims to develop and produce 26 new gas SRM's for use in establishing the accuracy of motor vehicle emissions tests, with primary emphasis

on measurement of emissions from heavy duty engines.

An automated gas analysis system for the certification of primary gas mixture SRM's was developed last year in a project cosponsored by NBS and EPA. Termed COGAS, for computeroperated gas analysis system, the arrangement is designed to sequentially sample and analyze up to 25 cylinders of a given gas mixture without supervision. COGAS has permitted a substantial reduction in the costs associated with SRM certification, while also producing a larger, more precise data base upon which the absolute gas concentration is derived. With slight modification, the system can also be used by other Federal agencies, State governments, and motor vehicle manufacturers as an instrument to significantly reduce the labor requirements in exhaust sampling and analysis.

Also in the area of auto emission testing, a long wavelength acoustic flowmeter was invented for measuring the rate of exhaust flow from the tailpipe of an automobile or truck. Linked with pollutant concentration detectors, this flowmeter could be used on production lines and in State and local test stations to determine compliance with EPA emission regulations. There is no competing technique for measuring the exhaust flow rate and the NBS device could eventually replace conventional testing equipment, which is comparatively expensive and cumbersome. Moreover, the flowmeter could provide more accurate information and be operated by unskilled personnel. Developed in the Center for Mechanical Engineering and Process Technology in cooperation

NBS research on the atmosphere ranges from studies at ground level to the upper regions. At top, physicist Ken Evenson adjusts a laser magnetic resonance spectrometer used in a project that has helped to revise estimates of how ozone levels are affected by fluorocarbons and supersonic transports.

with the Office of Environmental Measurements, the flowmeter may also have applications in developing fuelefficient engines or in medical research. for measuring human or animal breath flow rates.

In addition to auto-related pollution, the Bureau also addresses measurement needs associated with other sources of air pollution. For instance, NBS issued a sulfur dioxide SRM useful in measuring the pollutants from fossil fuel power plants. Also in FY 1978, Bureau researchers developed a nitrogen dioxide SRM which will be

The lower photo shows particulate matter in an urban air specimen as seen through an NBS electron scanning microscope. Urban air particulates are among the Standard Reference Materials that NBS is developing to help in monitoring air quality.

used to analyze emissions from nitric acid plants and power generation facilities.

Emissions from waste incinerators are still a significant air pollution problem, despite advances in control technology. In order to control these pollutants, engineers must know the chemical makeup of the waste material. Studies in the Center for Thermodynamics and Molecular Science led to the publication last year of thermodynamic data for 331 selected materials important to waste incineration processes. The data provide engineers with information that will help them design facilities to handle waste materials in a more effective and environmentally acceptable manner. This publication also offers engineers better measurements of the potential energy content of the waste stream for use in projects to recover heat from the incineration process. Undertaken in conjunction with a committee of the American Society of Mechanical Engineers and administered through the NBS Office of Standard Reference Data, its inclusion in the Bureau-operated standard reference data network ensures its

then be utilized to estimate the effects of specific substances in the atmosphere.

In a joint program with the National Oceanic and Atmospheric Administration, NBS identifies and experimentally measures critical chemical reactions using advanced laser spectroscopic techniques developed at the Bureau. Scientists in the Bureau's Center for Absolute Physical Quantities last year reported on research to determine the reaction rates when hydroperoxyl radicals-important components of the upper atmosphereinteract with nitric oxide. The NBSNOAA research involved the direct measurement of this chemical reaction for the first time. When this information was plugged into a computer model of the upper atmosphere, it significantly altered earlier analysis of the ozone depletion problem. Accordingly, supersonic transports are now judged to have little effect on the ozone layer. In fact, at some altitudes, they may actually create ozone. As a result of this research, however, damage to the ozone layer from fluorocarbons is estimated to be three times greater than had been previously assumed.

The latest basic data used as input by all models of stratospheric pollution. effects were published in FY 1978 by the Bureau as part of the NBS program of standard reference data evaluation and dissemination. Reaction Rate and Photochemical Data for Atmospheric Chemistry, NBS Special Publication 513, is a compilation of over 400 critically evaluated reaction rate items. It was cosponsored by the Department of Transportation, the National Aeronautics and Space Administration and three NBS groups-the Office of Standard Reference Data, the Office of Environmental Measurements, and the Center for Thermodynamics and Molecular Science. Like most of the Bureau's environmental research and services, this publication provides the measurement necessities for monitoring, evaluating, and improving the quality of our environment.