Interference studies were performed by spiking some cations, Ca2+, Mg2+, Co2+, Ni2+, Cr3+, Cu2+ and Mn2+ into Fe(III) 10 ppm solutions at the final concentration of 1, 5 and 10 ppm (10:1, 2:1 and 1:1 concentration ratios of Fe(III):interference ion). Peak heights obtained from these solutions were compared with standard Fe(III), 10 ppm. It was found that the system could tolerate these cations at least up to 1:1 concentration ratio (10 ppm Fe:10 ppm interference ion). Higher interference ratios were not studied because pharmaceutical preparations normally do not contain these minerals at higher amounts