Improvements in the spectrochemical analysis of aluminum with point-to-plane, high-voltage spark excitation are obtained by using nitrogen shielding of the discharge zone. The improvements, relative to excitation in air, include: increased spectral line intensity; decrease in the concentration equivalent of background; reduction of the influence of sample composition on background; reduction of the influence of the graphite counter electrode structure on spectral intensity; increased precision; and minimized interelement effects as judged by a reduction in the number of analytical curves required for analysis. Variables investigated in establishing the method are discussed and control parameters for consistency of operation are described. A bibliography on the development of gaseous shielding for spark discharges is included.
Charles K. Matocha and John Petit, "Spectrochemical Analysis of Aluminum Alloys Using Nitrogen Gas Shielding and Point-to-Plane Spark Excitation," Appl. Spectrosc. 22, 562-571 (1968)