Editors' Column
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innovations in plasma spectrometry SMI is widely recognized and respected as both a leader in atomic analysis and innovator of plasma-emission measurement techniques that have become accepted in numerous laboratories and industries worldwide. As a result of its continuing research and development efforts, SMI has evolved a new generation of low-cost plasma-emission spectrometers that combine the most desirable features of atomic-absorption and atomic-emission analyses, but provide greater capabilities than either. These new total-measurement systems, called Spectraspan III and Spectraspan IV, are compact, benchtop units that operate on safe, inert argon, and are designed for both quantitative and qualitative analysis. The systems offer a hardware flexibility and operating versatility that ensure consistently superior data, and the high productivity demanded by today's analytical requirements. Spectraspan IV performs automatic quantitative analysis of most elements on a sequential basis from major to trace concentrations including many of the so-called difficult elements. Rapid, comprehensive qualitative analysis is also available. Operating efficiency of the Spectraspan IV is improved through the use of a built-in INTEL microprocessor. The most attractive feature, however, is the price which further reflects SMI's innovativeness. While Spectraspan IV offers far more potential, it is priced competitively with a t o m i c absorption units. Spectraspan III, the most versatile plasma-emission spectrometer, incorporates the same unique features as Spectraspan IV p l u s the ability to perform simult a n e o u s quantitative analysis of up to 2 0 different e l e m e n t s . And the system price is also surprisingly modest. If you want to increase your capabilities without increasing costs, do it with a Spectraspan III or Spectraspan IV system. Call SMI today for details. SMI is the innovative company that has more plasma-emission spectrometers in use by satisfied customers throughout the world than any other manufacturer.
SPECTRAMETRICS INCORPORATED 204 ANDOVER STREET. ANDOVER. MA 01810 (617) 475-7015 CIRCLE 197 ON READER SERVICE CARD 1178 A · ANALYTICAL CHEMISTRY, VOL. 4 9 , NO. 13, NOVEMBER
1977
a large number of trace metals in various media with detection limits which are more than adequate. However, in the case of determinations of trace and ultratrace levels of metals in cellular and subcellular components of the body, often suitable analytical methodologies are not available. Mr. Bretthauer further emphasized that the analytical chemist must not isolate him/herself in the laboratory but must become involved in interdisciplinary programs, especially at the planning stage. The analytical chemist is in a unique position to provide "detailed recommendations on the type and size of samples to be obtained, methods of sample preservation and preparation, and the methods of analysis. In recommending the method of analysis, he must consider the various available methods in terms of sensitivity, accuracy, selectivity, and cost-effectiveness. Finally, it is the prime responsibility of the analytical chemist to interpret the analytical data, provide qualifications with certain data if necessary, and to implement a quality assurance program to assess the validity of the data being provided." Mr. Bretthauer's final point to analytical chemists was to generate statistically valid data. This seems to be one of the major challenges to the analyst when dealing with environmental or biological samples. In addition to the problems inherent in the analysis of low levels of compounds, such an analyst must work with an extremely complex and variable matrix. This particular problem was previously addressed by R. O. Kagel of Dow Chemical at a meeting sponsored by the Manufacturing Chemists Association this past January. He advocated the use of the "10-10-10" principle, originally developed for the analysis of pesticide residues. Briefly, 10 determinations are made on a control sample, i.e. (in the residue studies), untreated crop soil or animal tissues, to determine interferences; 10 determinations are made on the control sample spiked with varying concentrations of the compound of interest to determine recoveries; finally, 10 determinations are carried out on different aliquots of the same sample to determine the precision of the procedure. The statistics of the analytical procedures can be verified by two or more independent laboratories. As adopted by the USDA and FDA, this procedure has worked well for the analysis of pesticide residues in animal tissues, plants, soil, and water; it should work equally well in the determination of environmental pollutants. Barbara Cassait
