Analysis of orthophosphate-pyrophosphate mixtures resulting from weak pyrophosphatase activities

Several methods of P i estimation commonly used in research on PP-hydrolase activity of various proteins were found inconvenient due to the ability of the excess of PP to decompose during the development of color in strongly acidic media. One of the procedures described by Delsal and Manhouri (20) with Metol as the reducing agent in mild acidic medium was found to be the method of choice for the estimation of weak PP-hydrolase activities. Another Delsal and Manhouri procedure (22) was found useful for the estimation of total P i + PP.