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Continuum Echelle Wavelength Modulated AA Sir: Professor Koirtyohann is to be commended for his recent REPORT (1) reviewing future needs in atomic absorption spectrometry. I was particularly pleased to note the reference to continuum échelle wavelength modulated atomic absorption (CEWM-AA) (2, 3) as "a system deserving of commercial development." Unfortunately, however, the REPORT seems to imply t h a t the development of C E W M - A A was accomplished solely at the University of Maryland. In point of fact, the development of C E W M - A A was a joint Villanova University-University of Maryland project under the joint supervision of myself (Villanova) and T. C. O'Haver (Maryland). T h e first C E W M - A A system was built at Villanova University by A. T. Zander, the University of Maryland graduate student first involved in the joint project. C E W M - A A itself is an extension of previous continuum source échelle monochromator work {4, 5) done at Villanova University in the mid-1970s. Literature Cited (1) Koirtyohann, S. R. Anal. Chem. 1980, 52 736 A. (2) Zander,A. T.; O'Haver, T. C; Keliher, P. N. Anal. Chem. 1976, 48, 1166. (3) Zander, A. T.; O'Haver, T. O; Keliher, P. N. Anal. Chem. 1977, 49, 838. (4) Keliher, P. N.; Wohlers, C. C. Anal. Chem. 1974,46, 682. (5) Keliher, P. N.; Wohlers, C. C. Anal. Chem. 1976,48, 140. P e t e r N. Keliher Department of Chemistry Villanova University Villanova, Pa. 19085
Just for the Record Sir: I was impressed by Roy Koirtyoh a n n ' s paper on the history of atomic absorption spectrometry (Anal. Chem. 1980,52, 736-44 A). It was well orga-
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1368 A · ANALYTICAL CHEMISTRY, VOL. 52, NO. 13, NOVEMBER 1980
nized, and he must be congratulated. However, I must protest the implication in Table I t h a t from 1955-62 development of AA took place mainly in Australia and New Zealand. T h e U.S. was "an underdeveloped country" during this period, according to Koirtyohann. Sir Alan Walsh of Australia first started work on AA in 1952. In 1954 he exhibited a working model of an AA spectrometer at the Institute of Physics Exhibition of Scientific Instruments at Melbourne, Australia. T h e reaction was zero. In 1955 he published the first of several brilliant papers outlining almost completely the theory of A A and the required components of a working instrument. At t h a t time the scientific community relegated this information to the category "only of academic interest." In 1958 he gave his first paper in the U.S. at the Louisiana State University International Symposium at Baton Rouge, La., which was organized in those days by Phil West. Impressed by his lectures and the tremendous potential of the technique, I started research on AA at Esso Research and t h a t year built the first instrument in the U.S.—a modified Perkin-Elmer Model 13. A systematic study of analytical sensitivities, chemical interferences, solvent effects, background correction, multielement hollow cathodes, etc., was undertaken, and Esso began to use the method for routine analysis. Many lectures at local and national ACS and SAS meetings followed. By 1959 several laboratories in Australia were interested in trying out the method. CSIRO arranged for one small Australian manufacturer to make hollow cathode lamps, for a second to manufacture burners and mechanical items, and for a third to make electronic equipment. T h e monochromators were imported. About 1960 Sir Alan again visited Baton Rouge, followed by a visit to the Pittsburgh Conference, which in those days was still held in Pittsburgh. At a
A n e w Analytical C18 column for LC. Plain f a c t s from Perkin-Elmer. This analytical C18 column design represents a significant advance in practi cal liquid chromatography. While maintaining a selectivity that matches the best, the Perkin-Elmer*/Analytical C18 column achieves efficiency that's better than all the rest. Our new column facility tests each column individually to a minimum plates per meter of Ν = 24,000. Each efficiency measurement is obtained using low dead-volume instru mentation designed specifically to assure accurate interpretation of column performance. In practice, however, the performance of these columns may be limited by the extra-column volume of the chromatographer's LC system or the response time of the detector used. Technical excellence speaks for itself. The facts are plain, and they're all here. Compare the figures below with those for any other analytical C18 col umn. Then make your own trials and s e e the results. Column Characteristics Dimensions, ID mm χ length mm Effective chromatography surface Description of: Bonding Capping Pore Size, Â Maximum peak asymmetry, 4.3σ Pore volume (Vp), cc/gm Coating level, percent Void volume (V'o), ml Flow resistance (Φ) k reproducibility of selected molecular probes * reproducibility of selected molecular probes
area, m 2 /gm
ACID BASE NEUTRAL ACID BASE NEUTRAL
Recommended temperature operating range Solvent considerations for improved results
Particle size by volume average, πΐμ
Perkin-Elmer*/ Analytical C18 Part No. 0258-0184 4.6x250 360 ± 10% ODTMCS TMS 70±10 1.2 0.7 11±1 3.2
