Summary Of Lane-Eynon Titration

Lane-Eynon titration method is one of the method of determining the concentration of reducing sugars in a sample by using titration. It is based on the determination of the volume of a test solution required to reduce completely a known volume of alkaline copper reagent. The titration takes place in a boiling solution. The end-point is indicated by the use of an internal indicator which is methylene blue. In approximate titration, 15 mL of solution C and Fehling’s solution (Mixture of 5 mL Fehling’s A solution and 5 mL Fehling’s B solution) is boiled in conical flask. The mixture of solution C and Fehling’s solution turns brick-red. 2 drops of methylene blue is then added into the boiling solution and turns the solution blue. Then, sample solution C, diluted from strawberry jam sample is titrated into the boiling Fehling’s solution. The end-point is reached when the

The inverted solution C is used to carry out another titration with Fehling’s solution to determine the concentration of reducing sugars as invert after hydrolysis, where all sucrose are hydrolyzed into glucose and fructose. By carrying out two titrations, we can therefore determine the concentration of reducing sugars obtained from the hydrolysis of sucrose by finding the difference between the concentration of reducing sugars of both titrations. One molecule of sucrose is made up of one molecule of glucose and one molecule fructose joined by 1,2-glycosidic linkage. Therefore, the concentration of reducing sugars obtained from the hydrolysis of sucrose is multiplied with a factor of 0.95 (the molecular weight of sucrose which is 342 g/mol to the total molecular weight of glucose and fructose which is 360 g/mol). The value obtained from this step is the concentration of sucrose present in the strawberry jam sample, which is