Removal of phosphate and silicate interferences in the determination of magnesium, calcium and strontium by atomic absorption spectrometry

Abstract

A number of ions affect the absorbance of magnesium, calcium and strontium in a fuel-rich air-acetylene flame and this effect is removed by the presence of catechol or pyrogallol. An investigation of the removal of the interfering effect of silicate or phosphate using the continuous titration technique revealed a stoicheiometric relationship due to the formation of anionic complexes between pyrogallol and silicate or phosphate, i.e., 4 : 1 and 3 : 1, respectively. This stoicheiometry has been confirmed by spectrophotometric measurements.