Fluorimetric determination of manganese at the nanogram level by catalytic oxidation of pyridoxal 2-pyridylhydrazone by hydrogen peroxide

Abstract

The development and optimisation of a fluorimetric reaction rate method for the determination of Mn(II) is described in detail. The method is based on the enhancement by Mn(II) of the reaction between pyridoxal 2-pyridylhydrazone and hydrogen peroxide. Equations for the kinetics of the catalytic and non-catalytic reaction are developed, and the appropriate energies of activation are determined. Using several kinetic methods (tangent, differential, fixed-time and fixed-intensity) micro-amounts of Mn(II)(0.05–8 ng ml^–1) can be determined. The influence of foreign ions on the accuracy of the results is investigated and the method is applied to the analysis of manganese in food samples. The characteristics of the fluorimetric methods are critically compared with those described previously.