The simultaneous determination of a number of elements by atomic absorption is based upon the combination of desired characteristic radiations from hollow cathode tubes into a single, collimated polychromatic beam that is passed through the absorbing medium, is then resolved into its components, and each component is brought onto a detector. The radiations are combined by locating each source behind a slit that is so positioned with respect to a diffraction or dispersion element to satisfy the diffraction or dispersion equations under conditions which bring each beam along a common path to a single exit slit. The combined beam is resolved into its components by conventional spectrometric principles. Methods by which the optics may be folded to accommodate all elements within a single enclosure are described. The sensitivity and precision of analysis obtained by this method were found to be equivalent to the results of conventional single element determinations.
R. Mavrodineanu and R. C. Hughes, "A Multichannel Spectrometer for Simultaneous Atomic Absorption and Flame Emission Analysis," Appl. Opt. 7, 1281-1285 (1968)