D. C. powder arc excitation has been considered as unsuitable for quantitative spectrochemical analysis because of its poor reproducibility. Investigation of this reproducibility is made in the case of ferro-chrome analysis with the following results.
(1) If the source conditions such as arc current, gap distance and prearc time are properly chosen, the reproducibilityis fair, its coefficient of variation being under 5 %.
(2) Experimental conditions for obtaining fair reproducibility are common to the determinations of Mn, Cu and Si in ferro-chrome.
(3) Effects of selective volatilization should not be overestimated in the said determinations.
(4) In anode excitation, it is better not to give prearc time, but in cathode excitation, it may be advisable to allow some prearc time.
(5) Fair reproducibility is attained by using the total arc column as light source.
(6) Anode excitation gives better results than cathode excitation in this investigation.
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