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cases. Copper and lead were analyzed by atomic absorption, and detection limits of approximately 2 X 10"11 gram were obtained. All of the analytical curves showed good linearity over two to three orders of magnitude in concentration. The relative standard deviation was usually between 4-7% at concentrations one order of magnitude greater than the detection limit. In Figure 1, typical re-

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A silicon-intensified target vidicon tube (SIT) is evaluated for analytical use in the determination of 17 elements in an Ar-separated C2H2/air flame and 5 elements in an Ar-separated C2H2/N2O flame using combined atomic emission and atomic fluorescence as excited by a 150 W CW EIMAC xenon arc lamp. Benefits of combining emission and fluorescence signals in multielement analysis are experimentally shown. Limits of detection are approximately 100 times worse than previously reported by atomic fluorescence alone using a conventional spectrophotometer with the same 150 W EIMAC lamp. Linear dynamic ranges are between ∼10 and ∼100 for elements analyzed in the C2H2/air flame and are as high as 1000 for elements in the C2H2/N2O flame. Little or no use of the SIT and many similar image detectors for multielement analysis via atomic emission and/or atomic fluorescence is predicted at the present “state of the art.”

In recent years, electrodeless discharge lamps (EDLs) have been put forth as intense sources for atomic spectrometry. However, it has not been until recently that work involving temperature-controlled (thermostated) EDLs has resulted in stable, intense, reliable EDL sources for atomic spectrometry. It has previously been demonstrated that single-and multielement EDLs are very sensitive t o temperature changes when operated with a thermostated antenna ( I , 2). The insensitivity of spectral output of EDLs operated with the thermostated "A"-antenna to changes in microwave power has been discussed previously (1-3). Some of the reasons given for using thermostated EDLs have been: microwave generators are difficult t o stabilize adequately, whereas air temperatures can be regulated with good precision; and changes in the coupling efficiency between the microwave field and the EDL discharge can, in the absence of temperature control, lead to drastic changes in lamp spectral output. Until recently ( 4 ) , one microwave generator per antenna had been used when operating EDLs. This is readily understood when one considers the myriad of papers on EDLs and the art and skill needed to utilize EDLs for analytical studies. However. with the insensitivity of thermostated EDLs to changes in microwave power, it is readily conceivable that more than one thermostated EDL could be operated simultaneously from one microwave generator utilizing a microwave power divider and that such a system would be very advantageous for multielement analysis. Norris and West ( 4 ) have reported the use of a two-port power divider for two dual-element EDLs and mentioned that it was a n economical means of illuminating a flame cell with radiation from more than one EDL simultaneously.In this study. thermostated EDLs operated a t their optimal temperatures and powered by one microwave generator using a power divider are evaluated. Detection limits for atomic fluorescence spectrometric measurement of several elements with these EDLs were obtained and compared with other published results.