Kolorimetrische Glucosebestimmung

Messung einer Blutglukose-Analoglösung mit der DNS-Methode

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

Ziel

Die Glucosekonzentration mithilfe der Dinitrosalicylsäure-(DNS-)Kolorimetrie bestimmen und die Chemie reduzierender Zucker verstehen.

Hintergrund

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.

Sicherheitswarnungen

  • 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

Erforderliche PSA

goggles gloves lab_coat

Materialien

  • 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)

Ausrüstung

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

Durchführung

1

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

10 Min.
2

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

5 Min. 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 Min. Use tongs for hot tubes
4

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

2 Min.
5

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

5 Min.
6

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

15 Min.
7

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

18 Min.

Erwartete Ergebnisse

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.

Aufräumen

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

Details

Kategorie
Colorimetry
Schwierigkeit
Intermediate (High School)
Dauer
60 Min.
Geschätzte Kosten
$10,00
Schritte
7
Materialien
4

Weitere Experimente

Analyse von Lebensmittelfarben durch Spektrophotometrie 60 min Eisenbestimmung in Wasser 75 min Kolorimetrische Phosphatbestimmung 90 min Kolorimetrischer Proteintest (Bradford-Methode) 60 min Spektrophotometrische Analyse eines Gemisches 75 min Spektrophotometrische Bestimmung von Aspirin 75 min Verifikation des Lambert-Beer'schen Gesetzes 60 min

Frequently Asked Questions

What is the objective of Kolorimetrische Glucosebestimmung?
Die Glucosekonzentration mithilfe der Dinitrosalicylsäure-(DNS-)Kolorimetrie bestimmen und die Chemie reduzierender Zucker verstehen.
How difficult is Kolorimetrische Glucosebestimmung?
This experiment is rated as Intermediate (High School). It takes approximately 60 minutes to complete.
What safety precautions are needed for Kolorimetrische Glucosebestimmung?
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 Kolorimetrische Glucosebestimmung?
The main materials required are: DNS reagent, Glucose stock solution, Unknown sugar solution, Distilled water.
What results should I expect from Kolorimetrische Glucosebestimmung?
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.