Letters
An Absorbing Question Sir: I have recently had occasion to compare the nomenclature of absorbance spectroscopy that is recommend ed to analytical chemists by your JOURNAL and Applied Spectrosco py with the nomenclature recom mended to physical chemists by IUPAC. The only differences are IUPAC's use of specific absorption coeffi cient and molar absorption coefficient for the quantities 1//C logio Io/I and \/ICM logio Io/I, where I0 and / are the intensities, or power, of radiation which enter and leave the sample, re spectively, corrected for window ab sorption and reflection losses, / is the sample length, and C and CM are the mass concentration and the molar concentrations, respectively. You rec ommend the terms absorptivity and molar absorptivity for these quan tities.
The purpose of this letter is to re quest, with the deference that is ap propriately shown by a physical chem ist who makes such a request to A N A LYTICAL C H E M I S T R Y , that you re consider the desirability of your no menclature. I base this request on the following considerations. Absorptivity has an in ternationally accepted meaning as l~l-abJi where 0abs and φι are the power absorbed by, and incident on, a sample, respectively. This usage of ab sorptivity is consistent with such tra ditional definitions in physics as those of conductivity and resistivity, and I do not know of a definition of a word ending in "ivity" that involves the concentration of the medium. Further, the term absorption coefficient, either specific or molar, appears to me to be consistent with the traditional terms for these quantities, which have usual ly had the ending "coefficient".
My interest in this matter is peda gogical as well as the minimization of the considerable confusion that al ready exists in scientific nomen clature. A student who is given differ ent names for the same quantity in analytical and physical chemistry courses is placed under an unneces sary burden of potential confusion. Thank you for considering this re quest, which is not, I think, a trivial matter. J o h n E. Bertie Department of Chemistry The University of Alberta Edmonton, Alta., Canada T6G 2G2
Reply: Interested readers are invited to send their comments to A N A L Y T I CAL C H E M I S T R Y .
AN INVITATION TO ATTEND
EXPOCHEM '79 • October 22-25, 1979 • Astrohall • Houston, Texas
hundreds of booths with the latest in industrial and biomedical instrumentation, • shown by the corporations on the leading edge of technology. T_T over one hundred invited papers by acknowledged experts in the areas of Π ϋ ί Ι Γ · • High-Resolution Gas Chromatography • Chromatographic Analysis in the Petroleum Industry • Analytical Systems Based on Gas Chromatography — Mass Spectrometry • Quantitative Thin-Layer Chromatography • High-Performance Liquid Chromatography • Liquid Chromatographic Detection Systems • Ion-Selective Electrodes • Analytical Chemistry of Surfaces • Trace Analysis of Elements and Molecules • Advanced Concepts in Automated Instrumentation • Trace Analysis of Pollutants in the Environment (Air and Water) • Bioanalytical Mass Spectrometry • Analytical Advances in Pharmacology — Toxicology. A ^--^-4-ww»^! · nine intensive short courses on October 20 and 21, / \ . H d l V l · 1979, preceding the show. FOR FULL DETAILS AND REGISTRATION INFORMATION, WRITE: Dr. A. Zlatkis, Expochem '79, Chemistry Department, University of Houston, Houston, TX 77004. Or telephone direct: Area Code (713) 749-2623.
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CIRCLE 64 ON READER SERVICE CARD
808 A · ANALYTICAL CHEMISTRY, VOL. 5 1 , NO. 8, JULY 1979
