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1522 A · ANALYTICAL CHEMISTRY, VOL. 54, NO. 14, DECEMBER 1982
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omization rate. The furnace atmosphere also heats quickly, enhancing the decomposition of gas-phase molecules. The result is slightly increased sensitivity and a drastic reduction in both matrix interferences and background absorption problems. In fact, the authors say that there is no need for background or slope corrections except in high-solid-content samples such as seawater. A potential disadvantage of capacitive heating is the need for extremely fast electronics to accurately record the signals. Holcombe and Salmon (28) have described an instrument that gives both time (1 ms) and space (0.3 mm) resolution of absorbances within a 3-mm diameter furnace. The system is being used to study the effects of vaporization, desorption, oxidation, etc. on atom populations and the detailed distribution within the atomizer. Holcombe's studies represent the "detailed studies of principle and mechanisms" to which Laitinen referred. They are more likely to have an impact on the design of the next generation of furnaces than to dramatically change the way people use the present ones. Simultaneous multielement analysis, which is so common in emission spectroscopy, has not been significantly employed in atomic absorption. This may change based on work by Harnley et al. (29). They use a continuum source, a multichannel high-resolution échelle spectrometer, and wavelength modulation to get backgroundcorrected absorption data for 16 elements. Detection limits are comparable to conventional AA at wavelengths greater than about 280 nm. There is a gradual deterioration toward shorter wavelengths, with zinc (214 nm) being about an order of magnitude poorer than with a hollow cathode lamp source. The linear range is also limited with their system because the effective bandpass is about the same as the line width—not much narrower, as required in the simple equations that predict linearity. They have developed a novel method of automatically shifting the wavelength of measurement to the wings of the line when high absorbances are encountered. In this way, the measured absorbance can be kept low enough to be in the linear range, even at relatively high analyte concentrations. The system seems ripe for commercial development, because it provides high-quality background correction plus multielement capability. In most laboratories furnaces are used exclusively for atomic absorption, but Ottaway and co-workers (30) have demonstrated that the furnace atmosphere is hot enough to excite useful emission from some of the more
