# Glutaraldehyde (CAS 111-30-8) — Complete Guide to Properties and Applications **Category:** Crosslinking Agent / Disinfectant | **Formula:** C₅H₈O₂ | **MW:** 100.12 g/mol --- ## What Is Glutaraldehyde? **Glutaraldehyde (CAS 111-30-8)** is a crosslinking agent / disinfectant with the molecular formula **C₅H₈O₂** and molecular weight **100.12 g/mol**. The IUPAC systematic name is **pentanedial**. It appears as a **colorless to pale yellow liquid with pungent odor**. ## Physical and Chemical Properties | Property | Value | Source | |----------|-------|--------| | CAS Number | 111-30-8 | | | Molecular Formula | C₅H₈O₂ | | | Molecular Weight | 100.12 g/mol | | | IUPAC Name | pentanedial | | | Appearance | colorless to pale yellow liquid with pungent odor | | | Melting Point | -14 °C | | | Boiling Point | 187–189 °C (decomposes) | | | Density | 1.06 g/cm³ (50% aq. solution) | | ## How It Works ### Aldehyde-Protein Crosslinking: The Chemistry of Fixation Glutaraldehyde is the most widely used chemical fixative for biological specimens destined for electron microscopy, owing to its unique ability to crosslink proteins rapidly and irreversibly while preserving ultrastructural detail. The crosslinking chemistry is more complex than simple Schiff base formation and involves multiple reaction pathways that contribute to the exceptional stability of glutaraldehyde-fixed tissue. The primary reaction is the nucleophilic addition of protein amino groups (lysine ε-NH₂, N-terminal α-NH₂) to the aldehyde carbonyls. The initial product is an unstable carbinolamine, which dehydrates to form a Schiff base (imine, –N=CH–). However, the imine linkage can hydrolyze back to the starting materials unless it is stabilized — which is exactly what happens in glutaraldehyde fixation because the dialdehyde can form two-point attachments. The second, more important mechanism involves aldol condensation and polymerization of glutaraldehyde itself. In aqueous solution at neutral to alkaline pH, glutaraldehyde undergoes base-catalyzed aldol condensation to form α,β-unsaturated oligomers containing two to eight monomer units. These oligomeric species bear multiple aldehyde groups capable of simultaneous reaction with multiple lysine residues on the same or different protein molecules. The resulting crosslinked network — protein–(glutaraldehyde oligomer)–protein — is essentially irreversible under physiological conditions. Additional crosslinking modes include Michael addition of protein nucleophiles (lysine, cysteine, histidine) to the α,β-unsaturated aldehyde groups generated through aldol condensation. The pyridinium crosslink formed by reaction of glutaraldehyde with two lysine residues to generate a stable quaternary pyridinium ring structure has been identified as one of the definitive crosslinks in glutaraldehyde-fixed tissue. The net effect is the rapid, dense, and irreversible crosslinking of cellular proteins into an insoluble matrix that is resistant to the organic solvents, heavy metal stains, and electron beam exposure encountered during electron microscopy sample preparation. Unlike formaldehyde (which primarily forms methylol adducts and methylene bridges through a slower, reversible process), glutaraldehyde fixation is essentially complete within minutes to hours and produces a structurally robust specimen that can be stored in buffer for months without degradation. ## How Does It Compare to Alternatives? | Reagent | CAS | Key Difference | Best For | |---------|-----|----------------|----------| | **Glutaraldehyde** | 111-30-8 | Reference compound | General use | | Formaldehyde (Formalin) | 50-00-0 | Monoaldehyde; slower, less complete crosslinking. Reversible under some conditions. Forms fewer and less stable crosslinks. Penetrates tissue faster than glutaraldehyde. | Light microscopy immunohistochemistry where antigen preservation is critical; large specimen fixation where penetration speed dominates | | Glyoxal | 107-22-2 | The smallest dialdehyde (C2). Forms shorter crosslinks between proteins (~4 Å vs ~7.5 Å for glutaraldehyde). Faster penetration but less stable fixation. Generally considered less toxic than glutaraldehyde. | Acid-free histological fixation for light microscopy; formaldehyde-free pathology laboratories | | Genipin | 6902-77-8 | Naturally occurring iridoid crosslinker from Gardenia fruit. Non-cytotoxic. Forms dark blue pigments upon crosslinking (colorimetric indicator). Slower reaction kinetics than glutaraldehyde. | Tissue engineering scaffolds and hydrogels where residual cytotoxicity is unacceptable; food-grade crosslinking applications | *Comparison data verified against supplier specifications.* ## Key Applications 1. **Biological Tissue Fixation for Electron Microscopy**: Glutaraldehyde at 2.5% concentration in 0.1 M sodium cacodylate or phosphate buffer (pH 7.2–7.4) is the universal primary fixative for transmission and scanning electron microscopy (TEM/SEM). Tissue samples (1–2 mm³) are immersed in fixative for 2–24 hours at 4 °C, followed by buffer washes and post-fixation with 1% osmium tetroxide to stain membranes. Glutaraldehyde preserves cellular ultrastructure with near-native fidelity — mitochondria, endoplasmic reticulum, Golgi apparatus, and cytoskeletal elements are all faithfully retained. Immunogold labeling requires careful control of fixation time and concentration to avoid excessive crosslinking that masks antigen epitopes; 0.1–0.5% glutaraldehyde with 4% formaldehyde is a common compromise for correlative light and electron microscopy. 2. **Enzyme Immobilization on Solid Supports**: Glutaraldehyde is the most widely used crosslinking agent for covalently immobilizing enzymes onto solid supports for industrial biocatalysis. The support (aminopropyl-functionalized silica, chitosan beads, amino-Sepharose) is first activated with glutaraldehyde, which attaches to surface amino groups through Schiff base formation. The enzyme is then coupled to the pendant aldehyde groups. This two-step protocol prevents enzyme-enzyme crosslinking and preserves catalytic activity. Immobilized glucose isomerase (for high-fructose corn syrup production), penicillin G acylase (for 6-APA production), and lipases (for biodiesel transesterification) are produced at multi-ton scale using glutaraldehyde crosslinking. 3. **High-Level Disinfection of Medical Devices**: A 2% alkaline glutaraldehyde solution (activated to pH 7.5–8.5 with sodium bicarbonate buffer) is a high-level disinfectant and chemical sterilant for heat-sensitive medical devices including endoscopes, respiratory therapy equipment, and dialysis instruments. At 20–25 °C, a 20-minute immersion achieves high-level disinfection (destruction of all vegetative bacteria, mycobacteria, fungi, and viruses). A 10-hour immersion at 20–25 °C achieves chemical sterilization (destruction of bacterial endospores). The alkylation of microbial proteins and nucleic acids by the aldehyde groups is the mechanistic basis of the biocidal activity. Activated solutions have a 14–28 day use life depending on the specific formulation. Proper ventilation and personal protective equipment are mandatory due to glutaraldehyde's irritant and sensitizing properties. 4. **Leather Tanning (Chrome-Free Alternative)**: Glutaraldehyde is an important tanning agent in leather processing, particularly for 'wet-white' leather production as an alternative to chromium(III) tanning ('wet-blue'). It crosslinks collagen fibers through the same lysine-targeted chemistry, producing leather with high hydrothermal stability (shrinkage temperature ~80–85 °C, compared to ~100 °C for chrome-tanned and ~60 °C for untanned hide). Glutaraldehyde-tanned leather is white, lightfast, and compatible with a wide range of dyes and fatliquors. The absence of chromium makes the leather more amenable to biodegradation at end-of-life and reduces the environmental burden of chromium-containing solid waste from leather processing. Combined tanning with synthetic tanning agents (syntans) and vegetable tannins can achieve shrinkage temperatures approaching chrome-tanning performance. 5. **Biomedical Material Fabrication — Heart Valve Bioprostheses**: Glutaraldehyde-crosslinked porcine aortic valves and bovine pericardium are the standard materials for bioprosthetic heart valve replacement. The glutaraldehyde treatment crosslinks the collagen-rich extracellular matrix, reducing antigenicity (by masking xenoantigens including the α-Gal epitope), increasing mechanical strength and fatigue resistance, and imparting resistance to enzymatic degradation by host collagenases and matrix metalloproteinases. Crosslinked valves are packaged in glutaraldehyde solution and require thorough rinsing before implantation. The primary failure mode after 10–15 years in vivo is calcification of the crosslinked tissue rather than mechanical failure, and anti-calcification treatments (ethanol, aluminum chloride, detergent extraction) are applied to extend valve durability. ## Handling and Storage - **Storage:** Store in a cool, dry, well-ventilated area. Keep container tightly closed when not in use. - **PPE:** Wear appropriate gloves, safety goggles, and lab coat. - **Ventilation:** Use in a fume hood or well-ventilated area. Always consult the Safety Data Sheet (SDS) from your supplier before handling. ## Frequently Asked Questions ### What is the CAS number of Glutaraldehyde? The CAS Registry Number is **111-30-8**. This unique identifier is registered with the Chemical Abstracts Service and serves as the authoritative reference for chemical substance identification in scientific literature, regulatory filings, and commercial transactions. When ordering Glutaraldehyde from any supplier, specifying the CAS number ensures you receive the correct compound regardless of naming variations. ### What is the molecular weight of Glutaraldehyde? The molecular weight is **100.12 g/mol** based on the molecular formula **C₅H₈O₂**. This value is calculated from the standard atomic weights of the constituent elements and represents the mass of one mole of the compound. For synthetic planning, use this value to calculate molar equivalents and prepare solutions of known concentration. ### What is Glutaraldehyde used for? Glutaraldehyde is primarily used as a crosslinking agent / disinfectant in organic synthesis and related chemical processes. The specific applications depend on the particular research or industrial context. For detailed application information, consult the product sections above or refer to the supplier's technical documentation and published synthetic protocols. ### How should Glutaraldehyde be stored? Store Glutaraldehyde in a cool, dry, well-ventilated area away from incompatible materials including strong oxidizing agents, strong acids, and sources of ignition. Keep the container tightly closed when not in use. Always consult the Safety Data Sheet (SDS) from your specific supplier for the most accurate and up-to-date storage recommendations, as conditions may vary by purity grade and formulation. ### Where can I buy Glutaraldehyde? Glutaraldehyde (CAS 111-30-8) is available from major chemical suppliers. Availability, pricing, and purity grades vary by supplier and region. Check the product sourcing section for CoreyChem availability or contact our sales team for sourcing assistance and bulk quotation. ### What is the purity of commercial Glutaraldehyde? Commercial Glutaraldehyde is typically available at ≥97% purity from major chemical suppliers. Higher purities (≥99%) may be available for specialized applications in pharmaceutical manufacturing and analytical standards. Always verify the specific purity grade and certificate of analysis (CoA) with your supplier before use in critical applications. ## Where to Buy **Glutaraldehyde is available in the CoreyChem catalog.** [View Glutaraldehyde (CAS 111-30-8) on CoreyChem →](https://careerchemical.com/product/111-30-8)