葡萄糖的比色测定

用DNS法测量血糖类似物

Colorimetry Intermediate (High School) 60 分钟 ~$10.00

目标

用二硝基水杨酸（DNS）比色法测定葡萄糖浓度，理解还原糖化学。

背景

The DNS method is a classic colorimetric assay for reducing sugars. 3,5-dinitrosalicylic acid (yellow) is reduced by the free aldehyde group of glucose to 3-amino-5-nitrosalicylic acid (orange-red). The color change occurs upon heating, and the intensity at 540 nm is proportional to the reducing sugar concentration. This method is widely used in food science and fermentation monitoring.

安全警告

  • DNS reagent contains NaOH — corrosive to skin
  • Boiling water bath — handle tubes with tongs
  • Cool tubes before opening to prevent splattering
  • DNS reagent stains skin yellow

所需PPE

goggles gloves lab_coat

材料

  • DNS reagent (100 mL)
    1% DNS in NaOH with sodium potassium tartrate
  • Glucose stock solution (100 mL)
    10 mg/mL in water
  • Unknown sugar solution (20 mL)
  • Distilled water (200 mL)

设备

Spectrophotometer or colorimeter Cuvettes Boiling water bath Test tubes (10) with caps Pipettes (1 mL, 5 mL) Ice bath Timer

步骤

1

Prepare glucose standards: 0, 1, 2, 4, 6, 8, 10 mg/mL by diluting the stock solution.

10 分钟
2

Add 1 mL of each standard and the unknown to labeled test tubes. Add 1 mL of DNS reagent to each tube.

5 分钟 DNS contains NaOH
3

Place all tubes in a boiling water bath for exactly 5 minutes. The color changes from yellow to orange-red.

5 分钟 Use tongs for hot tubes
4

Transfer tubes immediately to an ice bath to stop the reaction. Cool for 2 minutes.

2 分钟
5

Add 8 mL of distilled water to each tube and mix well.

5 分钟
6

Measure absorbance at 540 nm. Zero with the blank (0 mg/mL glucose).

15 分钟
7

Plot the calibration curve and determine the glucose concentration of the unknown.

18 分钟

预期结果

A linear calibration curve from 1–10 mg/mL glucose. The color intensifies from pale yellow (blank) to deep orange-red (10 mg/mL). Non-reducing sugars like sucrose give no color change.

清理

Neutralize DNS waste with dilute HCl before disposal. Clean test tubes immediately as dried DNS residue is difficult to remove.

详情

类别
Colorimetry
难度
Intermediate (High School)
时长
60 分钟
预估费用
$10.00
步骤数
7
材料
4

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Frequently Asked Questions

What is the objective of 葡萄糖的比色测定?
用二硝基水杨酸（DNS）比色法测定葡萄糖浓度，理解还原糖化学。
How difficult is 葡萄糖的比色测定?
This experiment is rated as Intermediate (High School). It takes approximately 60 minutes to complete.
What safety precautions are needed for 葡萄糖的比色测定?
Key safety precautions include: DNS reagent contains NaOH — corrosive to skin; Boiling water bath — handle tubes with tongs; Cool tubes before opening to prevent splattering.
What materials are needed for 葡萄糖的比色测定?
The main materials required are: DNS reagent, Glucose stock solution, Unknown sugar solution, Distilled water.
What results should I expect from 葡萄糖的比色测定?
A linear calibration curve from 1–10 mg/mL glucose. The color intensifies from pale yellow (blank) to deep orange-red (10 mg/mL). Non-reducing sugars like sucrose give no color change.