Xác Định Glucose Bằng Phép Đo Màu

Đo nồng độ glucose tương tự đường huyết bằng phương pháp DNS

Colorimetry Intermediate (High School) 60 phút ~$10,00

Mục tiêu

Xác định nồng độ glucose bằng phương pháp đo màu axit dinitrosalixylic (DNS) và hiểu hóa học đường khử.

Bối cảnh

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.

Cảnh báo an toàn

  • 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

PPE cần thiết

goggles gloves lab_coat

Vật liệu

  • 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)

Thiết bị

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

Quy trình

1

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

10 phút
2

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

5 phút 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 phút Use tongs for hot tubes
4

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

2 phút
5

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

5 phút
6

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

15 phút
7

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

18 phút

Kết quả dự kiến

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.

Dọn dẹp

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

Chi tiết

Danh mục
Colorimetry
Độ khó
Intermediate (High School)
Thời gian
60 phút
Chi phí ước tính
$10,00
Số bước
7
Vật liệu
4

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Frequently Asked Questions

What is the objective of Xác Định Glucose Bằng Phép Đo Màu?
Xác định nồng độ glucose bằng phương pháp đo màu axit dinitrosalixylic (DNS) và hiểu hóa học đường khử.
How difficult is Xác Định Glucose Bằng Phép Đo Màu?
This experiment is rated as Intermediate (High School). It takes approximately 60 minutes to complete.
What safety precautions are needed for Xác Định Glucose Bằng Phép Đo Màu?
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 Xác Định Glucose Bằng Phép Đo Màu?
The main materials required are: DNS reagent, Glucose stock solution, Unknown sugar solution, Distilled water.
What results should I expect from Xác Định Glucose Bằng Phép Đo Màu?
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.