Question

1.) A person is suspected of diabetes mellitus. He checks his blood glucose level by glucose oxidase method. After the experiment, OD of his blood sample was obtained as 0.08. Based on the glucose standard curve seen in the virtual lab, calculate his blood glucose level. Is he had diabetes mellitus? (Note: Normal blood glucose level in our body is 70-110mg/dl).

2.) Find out the role and chemical reactions of the following reagents in the blood glucose level determination by glucose oxidase method.
a) Sodium sulphate – Zinc sulphate solution
b ) Glucose oxidase reagent
c) Peroxidase

3.) A person did estimation of blood glucose level by glucose oxidase method by referring the virtual lab procedure. But he forgot to add ortho - toluidine reagent during glucose oxidase reagent preparation.
a) What is the observation of the result?
b) Suggest three other chemicals used in place of ortho - toluidine?

Answer 1

2. Role of following chemical reagents:-

• Sodium sulphate/Zinc sulphate solution - Aids in elimination of unwanted protein matter present in blood sample.
• Glucose oxidase reagent -  Glucose oxidase catalyse the oxidation of Beta D- glucose present in the plasma to D glucono -1 ,5 - lactone with the formation of hydrogen peroxide.

3.Glucose oxidase catalyse the oxidation of Beta D- glucose present in the plasma to D glucono -1 ,5 - lactone with the formation of hydrogen peroxide; the lactone is then slowly hydrolysed to D-gluconic acid. The hydrogen peroxide produced is then broken down to oxygen and water by a peroxidase enzyme. Oxygen then react with an oxygen acceptor such as ortho toluidine which itself converted to a coloured compound, the amount of which can be measured colorimetrically.

• Thus is absence of ortho- toluidine there will be no coloured complex formed and hence colorimetric estimation wont be possible.
• 2:6-dichlorophenol-indophenol, 1-ascorbic acid.