Interference of phosphoric and sulfuric acid in atomic absorption spectroscopy for calcium and magnesium

Studies on the atomic absorption by the double aspiration method. I

Abstract

The influence of phosphoric and sulfuric acid on the atomic absorption of calcium and magnesium was studied by using a glass atomization chamber equipped with two atomizers.
The intensity of atomic absorption of calcium and magnesium was increased considerably by supplying calcium or magnesium solution from one atomizer and phosphoric or sulfuric acid from the other.
The enhancing effect observed by this double aspiration method could not be ascribed to physical factors, such as viscosity and surface tension of the solution, acetylene pressure and characteristics of aspiration chamber, but to some chemical reactions occurring in the flame.
The depressing effect of phosphoric or sulfuric acid on the ordinary atomic absorption of calcium or magnesium was considered to be caused by the formation of phosphate or sulfate in solution which would then give refractory substances in the acetylene flame.