1985 年 105 巻 6 号 p. 569-573
In out previous paper, a mixture of Ti (IV) and 4-(2-pyridylazo) resorcinol (Ti-PAR reagent) was recommended to be useful in the spectrophotometric determination of trace amounts of hydrogen peroxide. The absorbance at 508 nm was proportional to the concentration of hydrogen peroxide. The Ti-PAR reagent was successfully applied to assays of both hydrogen peroxide and sulfite added as a food additive for bleaching by the same procedure. Aliquot amounts of sample solution were pipetted into six volumetric flasks, and graded amounts of standard hydrogen peroxide solution were pipetted into them. The absorbances of sample solutions colored by the Ti-PAR reagent were plotted as ordinate and the concentration of added hydrogen peroxide as abscissa. In the presence of hydrogen peroxide in the sample, the plots of absorbance verses concentration of added hydrogen peroxide as standard intersected the abscissa on the left-hand side of its origin, and the value of the intercept showed the concentration of hydrogen peroxide in the sample solution. On the other hand, the added hydrogen peroxide was consumed through the redox reaction with sulfite in sample. Consequently, the plots of absorbance verses concentration of hydrogen peroxide added as standard intersected the abscissa on the right-hand side of its origin, the value of the intercept of abscissa showed the concentration of sulfite in the sample solution. The present method made it possible to determine both hydrogen peroxide and sulfite in amount ranging from 0.02 to 6.5 ppm and from 0.04 to 9 ppm, respectively, by using 100 g of food sample. In both cases the coefficients of variation were less than 5%.