The determination of silver, copper, zinc and magnesium in aluminium alloys by atomic absorption spectroscopy has been previously reported'*". The sample was dissolved by digestion with sodium hyclroxide solution ; the solution was then acidified with nitric acid, suitably diluted and atomised in an air-coal gas flame. The copper determinations were unaffectecl by the presence of other elements but the silver, zinc, and magnesium absorbances were appreciably lowered in the presence of relatively large amounts of aluminium, although these effects could be compensated by using standard solutions containing the same concentration of aluminium as the samples to prepare calibration curves.
When this technique was applied to the analysis of commercial alurninium alloys containing elements such as silicon, titanium, chromium and manganese, the results for magnesium were invariably low. This difficulty was partially overcome by the USC of the standard addition technique, but this depends on the assumption that the absorbance varies linearly with concentration over a fairly wide range. This, of course, is not necessarily true and must be checked in each separate type of alloy, thus at least trebling the number of determinations required for a single analysis. Another problem encountered in attempting to analyse commercial aluminium alloys was the difficulty associated with the atomisation of elements such as chromium and zirconium which do not show any absorption in the air-coal gas flame.
A major advance in atomic absorption spectroscopy technique over the past few years has been the use of flames which are hotter than the air-coal gas flame. The use of air-acetylene flames has increased the number of elements which can be determined to about thirty by addingmetals such asmolybdenum, tin, chromium, etc. Some chemical interferences were also removed in this flame, e.g. the effect of sodium on the determination of magnesium 3. The refractory elements such as titanium, zirconium, silicon, etc., were added in 1965 when WIJLIS~ introduced the nitrous oxide-acetylene flames. It isnow possible to determine about sixty elements by atomicabsorption spectroscopy.
The increase in the level of noise on the output meter due to emission from the hotter flames, particularly when elements with resonance lines around 3000 A are determined, is a minor drawback. SULLIVAN AND WALSH~ have recently produced hollow-cathode tubes where the intensity of the resonance line is greatly enhanced. It Aural. Ckim. Acla, 40 (1968) fjO3-512 Artal, Ckim. AcCn, 40 (x968) 503-512 Aural. Chim. Ada, 40 (1968) 503-512 SUMMARY The analysis of ahuninium-base alloys for silver, copper, magnesium, zinc, chromium, and zirconium by atomic absorption spectroscopy is described. The use Awl. Chinr. Ada, 40 (1968) 503~-512 A.