Determination of formaldehyde using a kinetic-spectrophotometric method. Part II. Oxidation of N-methyl-substituted-1,4-phenylenediamines with hydrogen peroxide

Abstract

A kinetic-spectrophotometric method is proposed for the determination of HCHO based on its “catalytic” property to oxidise N,N-dimethylphenylenediamine (DMPDA) by H₂O₂. The sensitivity at optimum conditions with this method is 1.3-fold greater than the corresponding oxidation of p-phenylenediamine (PDA). The condensation reaction step leading to the Bandrowski Base is much slower with DMPDA than with the PDA oxidation process. Other analytical parameters remain virtually unchanged and the detection limit lies in the range of a few p.p.m. However, the N,N,N′,N′-tetramethyl-1,4-phenylenediamine is not oxidised by H₂O₂ even in the presence of HCHO.