# DBT JRF 2022 — Question 7

Exam: DBT JRF 2022 · Section: A · Topic: Biochemistry › Spectrophotometry & Glucose Estimation · Difficulty: Medium

## Question

You are measuring blood glucose level by glucose oxidase method. Following are the absorbance values that you got for the standard and the test sample:
| Sample | Concentration | A505 |
| --- | --- | --- |
| Standard 1 | 0.4 mmol/L | 0.120 |
| Standard 2 | 0.6 mmol/L | 0.180 |
| Standard 3 | 0.8 mmol/L | 0.240 |
| Unknown | ? | 0.210 |

## Options

- **A.** 0.65 mM
- **B.** 0.70 mM
- **C.** 0.725 mM
- **D.** 0.75 mM

## Answer

Option B

## Explanation

Glucose estimation by glucose oxidase method — linear interpolation from standard curve: Given data (from the table in the question): • Standard 2: [Glucose] = 0.6 mmol/L, A₅₀₅ = 0.180 • Standard 3: [Glucose] = 0.8 mmol/L, A₅₀₅ = 0.240 • Test sample: A₅₀₅ = 0.210 (falls between Standard 2 and 3) Using linear interpolation: $[\text{Glucose}] = 0.6 + \frac{0.210 - 0.180}{0.240 - 0.180} \times (0.8 - 0.6) = 0.6 + \frac{0.030}{0.060} \times 0.2 = 0.6 + 0.10 = 0.70\,\text{mM}$ Answer: 0.70 mM (Option 2).

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