Abstract
The interference of perchloric acid on the thirteen elements in atomic absorption spectrophotometry in an air-acetylene flame, in an air-hydrogen flame and in a nitrous oxide-acetylene flame were studied.
A Nippon Jarrell-Ash Model AA-1 atomic absorption/flame emission spectrophotometer was used. Two slot type burners for air-acetylene flame (slit width : 0.5×100 mm) and nitrous oxide-acetylene flame (slit width : 0.4×50 mm), and a total consumption type burner (HETCO burner) for air-hydrogen flame were used.
Hollow cathode lamps of each element were used as sources of radiation.
As shown in Figs. 1 to 3, the interference of perchloric acid could be observed even in concentrations below 10-310-4M. Perchloric acid increased the absorption of magnesium, calcium, molybdenum, chromium and vanadium in an air-acetylene flame, on the other hand, it decreased the absorption of iron, nickel and cobalt.
Perchloric acid increased the absorption of magnesium, calcium and chromium in an air-hydrogen flame, and it also increased the absorption of molybdenum and vanadium in a nitrous oxide-acetylene flame.
As shown in Figs. 4 to 9, it has been found that the interferences of perchloric acid were greatly affected by the change of the fuel gas flow rate (pressure) as well as burner height. Perchloric acid generally gave relatively strong effects on the elements at the lower parts of the fuel-rich flame.
As shown in Fig. 10, such interferences could be also observed in the use of perchlorates such as sodium perchlorate and ammonium perchlorate. But coexisting cations had a strong influence on the results.
And such interferences were found to be peculiar to perchlorate ion, they were not observed with chloride ion, chlorate ion and hypochlorate ion.
