Determinación Colorimétrica de Glucosa

Medición del análogo de glucosa en sangre usando el método DNS

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

Objetivo

Determinar la concentración de glucosa usando el método colorimétrico del ácido dinitrosalicílico (DNS) y comprender la química del azúcar reductor.

Antecedentes

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.

Advertencias de seguridad

  • 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

EPP requerido

goggles gloves lab_coat

Materiales

  • 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)

Equipamiento

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

Procedimiento

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

Resultados esperados

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.

Limpieza

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

Detalles

Categoría
Colorimetry
Dificultad
Intermediate (High School)
Duración
60 min
Costo estimado
$10,00
Pasos
7
Materiales
4

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Frequently Asked Questions

What is the objective of Determinación Colorimétrica de Glucosa?
Determinar la concentración de glucosa usando el método colorimétrico del ácido dinitrosalicílico (DNS) y comprender la química del azúcar reductor.
How difficult is Determinación Colorimétrica de Glucosa?
This experiment is rated as Intermediate (High School). It takes approximately 60 minutes to complete.
What safety precautions are needed for Determinación Colorimétrica de Glucosa?
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 Determinación Colorimétrica de Glucosa?
The main materials required are: DNS reagent, Glucose stock solution, Unknown sugar solution, Distilled water.
What results should I expect from Determinación Colorimétrica de Glucosa?
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.