Tartrazine Handling & Lab Use Guidelines | Research Grade

Tartrazine is a synthetic lemon-yellow azo dye widely used in food-colorant research, analytical calibration, and bioassay development, requiring careful handling to ensure reproducible results and laboratory safety.

Chemical Name

Trisodium (4E)-5-oxo-1-(4-sulfonatophenyl)-4-[(4-sulfonatophenyl)hydrazono]-4,5-dihydropyrazole-3-carboxylate

Common Synonyms

FD&C Yellow No. 5; E102; Acid Yellow 23; CI 19140

Molecular Formula

C₁₆H₉N₄Na₃O₉S₂

Molecular Weight

534.36 g/mol

Appearance

Orange-yellow powder or granules

Solubility

Freely soluble in water; slightly soluble in ethanol; practically insoluble in most organic solvents

Recommended Storage

Store at room temperature (15–25 °C), protected from light and moisture in a tightly sealed container

Overview and Research Applications

Tartrazine (FD&C Yellow No. 5, E102, CI 19140) is a water-soluble monoazo dye belonging to the pyrazolone class. Its strong molar absorptivity in the visible range (~428 nm) makes it a practical chromophoric standard for UV-Vis spectrophotometric calibration. Beyond colorimetry, research-grade Tartrazine (SKU: T102059) is employed in:

• Analytical chemistry: preparation of absorbance calibration curves and instrument performance verification.
• Food science & toxicology: in vitro studies examining dye stability under varying pH, temperature, and light conditions.
• Environmental research: model contaminant for evaluating advanced oxidation processes, photocatalysis, and adsorption-based water-treatment technologies.
• Biological assays: tracer and flow-visualization agent in microfluidic and transport studies.

Understanding the physicochemical properties of Tartrazine is essential for designing reproducible experiments and interpreting spectroscopic data accurately.

Solution Preparation Protocol

Follow the steps below to prepare aqueous Tartrazine stock and working solutions:

1. Calculate required mass: Determine the target concentration (e.g., 1 mg/mL or 1 mM). Use the molecular weight of 534.36 g/mol for molar calculations.
2. Weigh accurately: Tare a clean, dry analytical balance vessel. Weigh the required amount of Tartrazine powder (SKU: T102059) using a calibrated analytical balance. Minimize dust generation — use a fume hood or local exhaust ventilation.
3. Dissolve in ultrapure water: Transfer powder to a volumetric flask containing approximately 80% of the final volume of ultrapure (Type 1) water. Tartrazine dissolves readily; gentle stirring or vortexing at room temperature is sufficient. Avoid heating above 60 °C to prevent potential degradation.
4. Adjust pH if required: For pH-dependent studies, use dilute HCl or NaOH to reach the target pH. Note that Tartrazine is stable across a broad pH range but may show slight spectral shifts under strongly acidic or alkaline conditions.
5. Bring to final volume: Transfer to a volumetric flask and make up to the calibration mark with ultrapure water. Mix thoroughly by inversion.
6. Filter if needed: Pass through a 0.45 µm nylon or PVDF membrane filter to remove particulates before spectrophotometric use.
7. Verify concentration: Measure absorbance at ~428 nm against a water blank; confirm against a freshly prepared calibration curve.

Note: Prepare solutions fresh or store as described in the Storage section. Avoid prolonged exposure to light during preparation.

Storage and Stability

Solid powder (SKU: T102059):

• Store at room temperature (15–25 °C) in a tightly closed, light-resistant container.
• Keep away from moisture and strong oxidizing agents.
• Under recommended conditions, the dry powder is stable for an extended period; consult the certificate of analysis (CoA) for the specific lot expiry date.

Aqueous solutions:

• Store in amber glass bottles or wrap containers in aluminum foil to protect from light.
• Refrigerate at 2–8 °C when not in active use; bring to room temperature before use.
• Discard solutions showing visible precipitate, color change, or microbial contamination.
• Prepare working solutions fresh for critical quantitative assays where accuracy is paramount.

Stability considerations: Tartrazine is susceptible to photodegradation under prolonged UV/visible-light exposure. Reductive conditions (e.g., ascorbic acid, sulfite) and strong oxidants (e.g., bleach, hydrogen peroxide) can cleave the azo bond, leading to decolorization and formation of degradation products. Avoid storage near such reagents.

Safety, Waste Disposal, and Regulatory Notes

Personal Protective Equipment (PPE): Wear appropriate laboratory coat, nitrile gloves, and safety glasses when handling Tartrazine powder or concentrated solutions. Use a dust mask or work in a fume hood when weighing powder to avoid inhalation of fine particles.

Health hazards: Tartrazine is classified as a permitted food colorant in many jurisdictions; however, research-grade material is not intended for consumption. Some individuals exhibit hypersensitivity reactions (e.g., urticaria, rhinitis). As a laboratory reagent, treat as a potential irritant. Refer to the Safety Data Sheet (SDS) supplied with the product for full hazard classification.

Environmental precautions: Do not discharge concentrated Tartrazine solutions into drains without treatment. As an azo dye, it is considered a potential environmental contaminant; local and institutional regulations for colored wastewater apply.

Waste disposal: Collect waste solutions in designated labeled waste containers. Dispose of in accordance with institutional, local, and national chemical waste regulations. Incineration at a licensed facility is an appropriate disposal route for concentrated waste.

Regulatory status: Tartrazine (E102) is approved as a food colorant in the EU, the USA (FD&C Yellow No. 5), and many other countries, but carries labeling requirements in some regions. Research-grade Tartrazine (SKU: T102059) is supplied for laboratory use only and is not a food-grade material.

Frequently asked questions

What is the maximum recommended concentration for preparing a Tartrazine stock solution in water?

Tartrazine is freely soluble in water; solubility values reported in literature are generally above 100 mg/mL at room temperature. For practical laboratory use, stock concentrations of 1–10 mg/mL are typical for analytical calibration, while environmental degradation studies may use higher concentrations. Always verify complete dissolution visually and by the absence of turbidity before use.

At what wavelength should Tartrazine absorbance be measured for spectrophotometric quantification?

The primary absorbance maximum of Tartrazine in aqueous solution is approximately 428 nm (literature values typically range from 425–432 nm depending on pH and ionic strength). Always verify the exact λmax for your specific instrument and solution conditions by running a full wavelength scan, and construct a calibration curve at that wavelength for accurate quantification.

Can Tartrazine solutions be autoclaved for sterile experiments?

Autoclaving is not recommended for Tartrazine solutions. Prolonged exposure to high temperature (121 °C) and steam may promote hydrolysis and degradation of the azo chromophore, altering the dye's spectral properties and concentration. For sterile applications, filter-sterilize solutions through a 0.22 µm membrane filter instead.

How should I verify the purity and identity of Tartrazine (SKU: T102059) upon receipt?

Upon receipt, inspect the Certificate of Analysis (CoA) provided with the lot for purity specification, assay method, and test results. Identity can be confirmed by UV-Vis spectroscopy (characteristic absorption at ~428 nm) and, if required, by TLC or HPLC against a reference standard. Report any discrepancies to Aladdin Scientific immediately.

References

1. European Food Safety Authority (EFSA). Scientific Opinion on the re-evaluation of tartrazine (E 102). EFSA Journal. 2009;7(11):1331.
2. U.S. Food and Drug Administration (FDA). Color Additives: FD&C Yellow No. 5 (Tartrazine). Code of Federal Regulations Title 21, Part 74.
3. Merck Index, 15th Edition. Entry: Tartrazine. RSC Publishing, 2013.
4. Colour Index International. Acid Yellow 23 (CI 19140). Society of Dyers and Colourists / American Association of Textile Chemists and Colorists.

Products are supplied for research and development use only. Not for use in humans, animals, diagnosis, or therapy.