Колориметрическое определение глюкозы

Измерение аналога глюкозы крови методом DNS

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

Цель

Определить концентрацию глюкозы динитросалициловым (DNS) колориметрическим методом и понять химию восстанавливающих сахаров.

Предпосылки

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.

Предупреждения по безопасности

  • 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

Требуемые СИЗ

goggles gloves lab_coat

Материалы

  • 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)

Оборудование

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

Процедура

1

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

10 мин
2

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

5 мин 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 мин Use tongs for hot tubes
4

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

2 мин
5

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

5 мин
6

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

15 мин
7

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

18 мин

Ожидаемые результаты

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.

Уборка

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

Детали

Категория
Colorimetry
Сложность
Intermediate (High School)
Продолжительность
60 мин
Прим. стоимость
$10,00
Шаги
7
Материалы
4

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Frequently Asked Questions

What is the objective of Колориметрическое определение глюкозы?
Определить концентрацию глюкозы динитросалициловым (DNS) колориметрическим методом и понять химию восстанавливающих сахаров.
How difficult is Колориметрическое определение глюкозы?
This experiment is rated as Intermediate (High School). It takes approximately 60 minutes to complete.
What safety precautions are needed for Колориметрическое определение глюкозы?
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 Колориметрическое определение глюкозы?
The main materials required are: DNS reagent, Glucose stock solution, Unknown sugar solution, Distilled water.
What results should I expect from Колориметрическое определение глюкозы?
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.