Analysis of Differentie Between the Methods of Acidimetric and Iodometric Titrimetry for Determination of Aldehydic Groups of Oxidized Dextran

A series of oxidized dextrans were prepared by oxidation of a definite amount of dextran with different amounts of 0.097 4 mol·L-1 sodium periodate solution.And a series of oxidized products of glycerol were also prepared by oxidation of different amounts of glycerol with same amounts of 0.097 4 mol·L-1 sodium periodate solution.Aldehydic groups in each of the above mentioned oxidized products were determined by both the acidimetric and iodometric titration.Significant difference among the results found by the two methods was observed.The variance was analyzed on the base of reaction mechanism of oxidation of dextran and by comparing with the process of oxidation of glycerol.As proved by the experimental data,the discrepancy in analytical results was arisen from the difference of molecular structures of the intermediate or side products in the course of oxidation of dextran.It was concluded that when the ratio of sodium periodate and sugar unit by amount of substance was controlled at less than 2,the method of acidimetric titration was preferred for the determination of aldehydic group of oxidized dextran.