Analyse des Colorants Alimentaires par Spectrophotométrie

Identification des colorants alimentaires artificiels par leurs spectres d'absorption

Colorimetry Intermediate (High School) 60 min ~$8,00

Objectif

Déterminer l'identité et la concentration des colorants alimentaires artificiels dans des boissons commerciales en mesurant leurs spectres d'absorption.

Contexte

Artificial food dyes have characteristic absorption spectra that serve as fingerprints for identification. FD&C Red No. 40 absorbs maximally at 504 nm, Blue No. 1 at 630 nm, and Yellow No. 5 at 428 nm. By scanning the absorption spectrum of a commercial beverage and comparing peak wavelengths with known dye spectra, students can identify which dyes are present and estimate their concentrations.

Avertissements de sécurité

  • Food dyes can stain clothing
  • Do not drink any samples after use in the lab
  • Handle cuvettes by the frosted sides only

EPI requis

goggles lab_coat

Matériaux

  • Standard food dye solutions (50 mL each)
    Red 40, Blue 1, Yellow 5 (0.01%)
  • Commercial beverages (50 mL each)
    2–3 colored drinks
  • Distilled water (200 mL)
    For dilutions and blank

Équipement

UV-Vis spectrophotometer (or colorimeter with multiple filters) Cuvettes (quartz or plastic) Pipettes Volumetric flasks (25 mL, 4 total)

Procédure

1

If using a spectrophotometer, scan each standard dye solution from 400 to 700 nm to identify the λmax (wavelength of maximum absorbance).

10 min
2

Record the λmax for each standard: Red 40 (≈504 nm), Blue 1 (≈630 nm), Yellow 5 (≈428 nm).

5 min
3

Dilute commercial beverage samples if too concentrated (absorbance should be below 1.0). Record all dilution factors.

10 min
4

Scan each beverage sample from 400 to 700 nm. Record the absorption spectrum.

15 min
5

Compare the beverage absorption peaks with the standard dye λmax values to identify which dyes are present.

10 min
6

If a calibration curve was prepared for a specific dye, calculate the dye concentration in each beverage (accounting for dilution).

10 min

Résultats attendus

Each beverage should show absorption peaks matching one or more standard food dyes. Green drinks typically contain both Blue 1 and Yellow 5. Orange drinks often contain Red 40 and Yellow 5.

Nettoyage

Pour dilute dye solutions down the drain with running water. Rinse cuvettes immediately to prevent staining.

Détails

Catégorie
Colorimetry
Difficulté
Intermediate (High School)
Durée
60 min
Coût estimé
$8,00
Étapes
6
Matériaux
3

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Frequently Asked Questions

What is the objective of Analyse des Colorants Alimentaires par Spectrophotométrie?
Déterminer l'identité et la concentration des colorants alimentaires artificiels dans des boissons commerciales en mesurant leurs spectres d'absorption.
How difficult is Analyse des Colorants Alimentaires par Spectrophotométrie?
This experiment is rated as Intermediate (High School). It takes approximately 60 minutes to complete.
What safety precautions are needed for Analyse des Colorants Alimentaires par Spectrophotométrie?
Key safety precautions include: Food dyes can stain clothing; Do not drink any samples after use in the lab; Handle cuvettes by the frosted sides only.
What materials are needed for Analyse des Colorants Alimentaires par Spectrophotométrie?
The main materials required are: Standard food dye solutions, Commercial beverages, Distilled water.
What results should I expect from Analyse des Colorants Alimentaires par Spectrophotométrie?
Each beverage should show absorption peaks matching one or more standard food dyes. Green drinks typically contain both Blue 1 and Yellow 5. Orange drinks often contain Red 40 and Yellow 5.