Effect of phytate on the in-vitro solubility of Al+, Ca2+, Hg2+ and Pb2+ as a function of pH at 37°C

The effect of phytate on the solubility of Al³⁺ and Pb^{2 +} has been investigated in vitro at 37°C across the pH ranges 3–7 (Pb²⁺) and 2–5 (Al³⁺). For both ions minimum solubility was found when the initial metal ion: phytate ratio was in the range 5:1–3:1 across the whole pH range. For Al³⁺ the solubility rose sharply either side of these ratios whereas for Pb^{2 +} solubility rose only slowly as the metal ion: phytate ratio was reduced. Hg²⁺ was totally soluble under all conditions tested. At pH 7 Ca²⁺ solubility was found to be at a minimum when the initial Ca : phytate ratio was 5 :1 irrespective of the initial Ca²⁺ concentration.