3,5-Dinitrosalicylic acid

3,5-Dinitrosalicylic acid the derivative of salicylic acid. 3,5-Dinitrosalicylic acid is used in the α-amylase assay, carbohydrase assay, and for the colorimetric determination of reducing substances^[1]. In Vitro:3,5-Dinitrosalicylic acid is a commonly used reducing sugar detection reagent. 3,5-Dinitrosalicylic acid undergoes an oxidation-reduction reaction with reducing sugars to generate derivatives, thereby producing a color change for quantitative detection of reducing sugar content.
Two different DNSA reagents were prepared:
1. Reagent preparation:
DNSA-1 reagent: 0.4M NaOH solution, and each 100mL solution contains a certain amount of heptahydrate.
DNSA-2 reagent: 0.7M NaOH solution, Each 100mL contains 2g 3,5-dinitrosalicylic acid.
2.Sample preparation:
Prepare a series of maltodextrin solutions of different concentrations (0.15 - 5.85mM). If the effect of calcium ions is to be studied, calcium chloride is added to the maltodextrin solution to a concentration of (40mM).
3.Test steps:
Take 2mL of sample and place it in a Folin-Wu sugar tube and add DNSA reagent. Heat the solution in a boiling water bath for precisely 5min and then cool it in cold running water for 5min. After cooling, dilute the solution to 25mL and measure the absorbance using a Unicam SP 1300 colorimeter with a green filter.
4.Result analysis:
Plot a curve with absorbance (A) as the ordinate and millimolar concentration of maltodextrin (M) as the abscissa. Compare the molar reduction values of different maltodextrins by plotting the slope of the absorbance-concentration curve of each maltodextrin versus the size (number of glucose residues) of the maltodextrin. If the absorbance value of the reagent is proportional to the number of reducing ends, the slope of the curve is zero; if the absorbance value is not proportional to the number of reducing ends and increases with the size of maltodextrin, the slope of the curve is greater than zero.