Method for quantifying permanganate-reducing compounds
View Patent ↗A method for quantifying the permanganate-reducing compounds (PRCs) in an acetic acid sample is disclosed. The method comprises establishing a correlation between permanganate absorbances of standard samples and their PRC contents and determining the PRC content of the acetic acid sample by measuring its permanganate absorbance of a reaction mixture containing a standard permanganate solution and the acetic acid sample. The permanganate absorbance is obtained by subtracting the manganese dioxide absorbance from the absorbance of the mixture.
1. A method for quantifying permanganate-reducing compound (PRC) content of an acetic acid sample, comprising:
(a) establishing a correlation between permanganate absorbances of standard samples and their PRC content by:
(i) preparing two or more standard samples with known PRC contents;
(ii) adding a known amount of a standard permanganate solution to each standard sample from (a)(i) to form a mixture;
(iii) for each standard sample, measuring the absorbance of the mixture (A mix ) at a selected wavelength in the range of 460 to 580 nm at a set reaction time;
(iv) for each standard sample, determining the permanganate absorbance (A perm ) at the set reaction time by subtracting from A mix the absorbance due to manganese dioxide (A MnO2 ) at the selected wavelength;
(v) establishing a correlation between permanganate absorbances and their PRC contents; and
(b) repeating steps (a)(ii) through (a)(iv) with the unknown acetic acid sample that contains an unknown amount of PRC to determine its PRC content.
2. The method of claim 1 wherein A MnO2 is determined by drawing a baseline across the base of a permanganate absorption band.
3. The method of claim 1 wherein the correlation is a calibration curve.
4. The method of claim 1 wherein the standard permanganate solution is a potassium permanganate solution.
5. The method of claim 1 wherein the set reaction time is from 10 to 30 min.
6. The method of claim 1 wherein a solvent is used to form the mixture.
7. The method of claim 6 wherein the solvent is selected from the group consisting of water, alcohols, carboxylic acids, amides, nitriles, and mixtures thereof.
8. The method of claim 7 wherein the solvent is water.