The determination of sodium in aluminium alloys by flame spectrophotometry with fuel-rich flames to reduce interference

Abstract

The determination of trace quantities of sodium in aluminium alloys by flame spectrophotometry offers a rapid and accurate control procedure. When conventional flames with a balanced fuel-air mixture are used, molecular oxide band spectra of iron and manganese are strongly excited, and interfere with the measurement of the sodium emission. The interference is much less in fuel-rich flames while the sensitivity to sodium is slightly increased. The use of fuel-rich flames therefore provides a more versatile and accurate method than those hitherto used. As in most methods for the determination of sodium it is advantageous to add lithium as an internal standard to compensate for minor variations in conditions. The results are of general application to the analysis of other materials which may contain iron and manganese, and possibly nickel and chromium.