Hydroquinone Solution: Uses, Handling & FAQs

Hydroquinone solution is a ready-to-use aqueous or solvent-based preparation of 1,4-benzenediol widely employed in research laboratories as an antioxidant, polymerization inhibitor, and photographic developing agent.

Chemical Name

1,4-Benzenediol (Hydroquinone)

CAS Number

123-31-9

Molecular Formula

C₆H₄(OH)₂

Molecular Weight

110.11 g/mol

Primary Applications

Antioxidant, polymerization inhibitor, photographic developer, analytical chemistry

Storage Condition

Store in a cool, dark, well-ventilated area away from oxidizing agents

What Is Hydroquinone Solution?

Hydroquinone solution is a prepared liquid formulation containing 1,4-benzenediol (CAS 123-31-9), an aromatic diol with the molecular formula C₆H₄(OH)₂ and molecular weight of 110.11 g/mol. The compound belongs to the class of phenolic antioxidants and is characterized by two hydroxyl groups positioned para to each other on a benzene ring. In solution form, it is supplied at defined concentrations to facilitate reproducible use in laboratory workflows without the need for weighing potentially hazardous solid material. Hydroquinone is readily oxidized to para-benzoquinone, a reaction that underpins many of its analytical and synthetic applications.

Research Applications of Hydroquinone Solution

Hydroquinone solution finds use across multiple research disciplines:

• Antioxidant and radical scavenger: Hydroquinone donates hydrogen atoms to free radicals, making it useful for protecting sensitive reagents and biological samples from oxidative degradation.
• Polymerization inhibitor: It is commonly added to monomer storage solutions to suppress premature radical polymerization, extending shelf life and ensuring experimental reproducibility.
• Photographic and imaging chemistry: Hydroquinone acts as a reducing agent in photographic developers, converting exposed silver halide crystals to metallic silver.
• Electrochemistry: The reversible hydroquinone/quinone redox couple (E° ≈ +0.70 V vs. NHE at pH 0, pH-dependent) is exploited in electrochemical studies, biosensor development, and as a redox mediator.
• Analytical chemistry: Hydroquinone is used as a standard or reagent in colorimetric and spectrophotometric assays.

Storage, Stability, and Handling

Proper storage is critical for maintaining the integrity of hydroquinone solution:

• Light sensitivity: Hydroquinone oxidizes upon exposure to air and light, causing discoloration (browning or darkening). Solutions should be stored in amber or foil-wrapped containers and protected from direct light.
• Temperature: Store at controlled room temperature or as specified on the product label, away from heat sources.
• Oxidizing agents: Keep away from strong oxidizers, which can accelerate degradation.
• Shelf life: Once opened, solutions should be used promptly; check for discoloration before use as a quality indicator.
• Personal protective equipment (PPE): Wear nitrile gloves, safety glasses, and a lab coat when handling. Work in a well-ventilated area or fume hood. Hydroquinone is classified as harmful if swallowed, inhaled, or absorbed through skin, and is a suspected carcinogen under some regulatory frameworks.

Safety and Regulatory Considerations

Hydroquinone is subject to regulatory classification in multiple jurisdictions. Key safety considerations include:

• GHS Hazard Classification: Typically classified as Acute Toxicity (oral, dermal), Skin Sensitizer, Eye Damage/Irritation, and potentially Carcinogenicity Category 2 depending on jurisdiction and concentration.
• SDS compliance: Always consult the current Safety Data Sheet (SDS) supplied with the product before use. The SDS provides first-aid measures, spill procedures, and disposal guidance.
• Waste disposal: Dispose of hydroquinone-containing waste according to local, institutional, and national environmental regulations. Do not pour down the drain without authorization.
• Environmental hazard: Hydroquinone is toxic to aquatic organisms and should not be released into the environment.

Note: Regulatory classifications may vary by country and concentration of solution. Always verify with the current SDS and local regulations.

Ordering and Specifications

Aladdin Scientific supplies hydroquinone solution under SKU H117393. When placing an order or evaluating suitability, consider the following:

• Concentration: Confirm the concentration listed on the current product page or Certificate of Analysis (CoA) matches your experimental requirements. Contact technical support if a custom concentration is needed.
• Purity and grade: Verify that the reagent grade meets the requirements of your assay (e.g., HPLC-grade solvent base where applicable).
• Volume options: Check available pack sizes on the product listing to select the quantity appropriate for your throughput.
• Certificate of Analysis (CoA): A CoA with lot-specific data is available upon request and should be retained for GLP/GMP documentation purposes.
• Lead time and shipping: Hydroquinone solution may be subject to hazardous materials shipping regulations; confirm packaging compliance and estimated delivery with your Aladdin Scientific representative.

Frequently asked questions

What is hydroquinone solution used for in research?

Hydroquinone solution is used as an antioxidant and free-radical scavenger, a polymerization inhibitor for monomer stabilization, a reducing agent in photographic developers, and a redox mediator in electrochemical and biosensor research. It also serves as a reference standard in colorimetric and spectrophotometric assays.

How should hydroquinone solution be stored to prevent degradation?

Hydroquinone solution should be stored in amber or light-protected containers at controlled room temperature, away from oxidizing agents, heat, and direct light. Solutions that have turned brown or dark should not be used, as discoloration indicates oxidation to para-benzoquinone.

Is hydroquinone solution hazardous, and what PPE is required?

Yes, hydroquinone is classified as harmful by ingestion, inhalation, and skin absorption, and is a potential skin sensitizer. Users should wear nitrile gloves, safety glasses, and a lab coat, and handle the solution in a well-ventilated area or fume hood. Always consult the current SDS (Safety Data Sheet) for detailed hazard and first-aid information.

What is the CAS number and molecular formula for hydroquinone?

Hydroquinone (1,4-benzenediol) has the CAS number 123-31-9, the molecular formula C₆H₄(OH)₂, and a molecular weight of 110.11 g/mol.

How can I obtain a Certificate of Analysis (CoA) for Hydroquinone solution SKU H117393?

A lot-specific Certificate of Analysis for Hydroquinone solution (SKU H117393) is available upon request from Aladdin Scientific. Contact customer service with your lot number, and the CoA can be provided for GLP, GMP, or quality documentation purposes.

References

1. March, J. Advanced Organic Chemistry: Reactions, Mechanisms, and Structure. Wiley-Interscience. General reference for hydroquinone chemistry.
2. Sigma-Aldrich / Merck product documentation for Hydroquinone, CAS 123-31-9. General physicochemical properties reference.
3. European Chemicals Agency (ECHA). Hydroquinone substance information. CAS 123-31-9.

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