Estimation of Phosphorus in Native and Modified Starches. Improvement in the Molybdovanadophosphoric Acid Method

The spectrophotometric method for estimation of phosphorus based on molybdovanadophosphoric acid complex has been improved for its sensitivity (8–10 fold) by reducing the reagents concentrations to one‐third and measuring the absorbance at its λ max (355 nm). The range of the method is brought down to 0.5 μg to 7 μg/ml for 1 cm light path. Phosphorus content of potato starch remained unchanged upon acid modification or oxidation with hypochlorite. Maize and tapioca starch, on the other hand, lost about 30–40% of their phosphorus upon acid modification. The difference probably lays in the state of phosphorus in the respective starch granules.