In this paper, we propose a spectrophotometric method for assessing the effect of organic ligands on the oxidizing properties of complexing agents (iron (III), copper (II)) and on the heterogeneous equilibrium in the magnesium-hydrophosphate system. An analysis of experimental data shows that glutamic acid at a concentration in solution from 50 to 250 mg/l does not affect the reduction of iron (III), however, the interaction of copper (II) with glutamic acid reduces the ability of Cu2+ to reduce by 9% and 39% at concentration in solution from 50 to 100 mg/l, respectively. The greatest complexing interaction with magnesium, in the "magnesium-hydrophosphate" system, was shown by proton pump inhibitors: rabeprazole and pantoprazole, and the smallest - esomeprazole and omeprazole.