Letters
first with 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.
Sadao Mori Department of Industrial Chemistry Faculty of Engineering Mie University Tsu, Mie 514, Japan
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SMI
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ANALYTICAL CHEMISTRY, VOL. 50, NO. 4, APRIL
the word. The term "exclusion" includes steric exclusion as well as ion exclusion which belongs to a different technique. It seems reasonable to assume that several proposed theories such as steric exclusion and restricted diffusion take each part of "size exclusion" mechanisms. This situation is similar to the fact that several adsorption or partition mechanisms are proposed for "Adsorption" or "Partition" Chromatography. To the end that we can use the consolidated terminology for the techniques, I propose that the term "Size Exclusion Chromatography (SEC)" be used to describe this chromatography instead of GPC, GFC, Gel Chromatography, and other related names.
1978
Graphite Furnace AA Sir: I would like to clarify a point raised by Ralph Sturgeon in his INSTRUMENTATION article, "Factors Affecting Atomization and Measurement in Graphite Furnace Atomic Absorption Spectrometry" [ANAL. CHEM., 49,1255A (1977)]. On page 1260 A he states, "It is the inseparability of the rate of heating of the atomizer and the maximum temperature which it attains that presents a major problem with commercial ET (electrothermal) atomizers employing threestage heating programs." He reiterates this throughout the text. This problem has been recognised and eliminated by at least one manufacturer of commercial atomizers. The Varian CRA-90, which was released in January 1976 and described [B. R. Culver and D. E. Schrader, Amer. Lab., 8 (3), 59 (1976)] in March 1976, allows independent selection of the heating rate and the maximum temperature. A ramp rate of up to 800 °C/s, a hold temperature of up to 3000 °C, and a hold time of up to 5 s may be independently selected for the atomization stage. I hope this letter will prevent your readers from gaining the mistaken impression that there is no commercial graphite furnace with the desirable characteristics specified by Dr. Sturgeon. P. R. Liddell Varian Techtron Pty. Ltd. 679/687 Springvale Road Mulgrave, Vic, Australia 3170
