Question

some possible errors during the quantitative test for carbohydrates

Answer 1

Some possible errors can be.

1) Benedict method i.e Estimation of glucose: The Benedicts quantitative reagent consists of the following ingredients, copper sulphate, sodium carbonate, sodium citrate or potassium citrate, potassium thiocyanate and potassium ferrocyanide. Of these, copper sulphate has to be very accurately measured which can possibly incur an error as the amount of copper sulphate reduced will correspond to the amount of glucose present in solution.

2) Reducing action of the sucrose: Sucrose being a non-reducing sugar because the carbon elements of the aldehyde groups are bonded in what's called a glycosidic bond , so that it cannot form an open-chain structure with an available aldehyde group. Moreover , sucrose contains acetal instead of hemiacetal. So this an error.

3) Lack of exact control of temperature.

4) Auto reduction of fehling solution.