Karnovsky's Fixative

Karnovsky's Fixative

Karnovsky’s Fixative is a dual-aldehyde fixation system combining glutaraldehyde and formaldehyde in a buffered solution for structural preservation of biological specimens. It is widely used in electron microscopy (EM) and histology to provide balanced fixation of proteins and cellular architecture.

This formulation leverages the crosslinking strength of glutaraldehyde with the rapid penetration of formaldehyde, resulting in improved preservation of ultrastructure compared to single-component fixatives. Supplied as a pre-measured kit, it enables consistent preparation and reproducibility across experiments.

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Key Features & Benefits

• Dual-aldehyde formulation: combines glutaraldehyde and formaldehyde for effective fixation
• Designed for electron microscopy: supports preservation of cellular ultrastructure
• Balanced fixation mechanism: rapid penetration with strong crosslinking
• Pre-measured kit format: simplifies preparation and improves consistency
• Buffered system: supplied with phosphate buffer for controlled fixation conditions
• Reproducible results: standardized composition reduces variability

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Product Details

• Product name: Karnovsky’s Fixative
• Fixative components: Glutaraldehyde and formaldehyde
• Glutaraldehyde concentration: 50% stock (10 mL ampoule)
• Formaldehyde concentration: 16% stock (2 × 10 mL ampoules)
• Buffer: 0.2 M phosphate buffer (50 mL)
• Preparation: One-step working solution preparation
• Storage (working solution): Stable up to 6 months at 4°C
• Packaging: Kit format (5 kits per package)

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Typical Applications

Electron microscopy (EM)
Used for fixation of biological specimens prior to transmission or scanning electron microscopy, preserving ultrastructural detail.

Histology and tissue preparation
Provides structural stabilization of tissues for sectioning and downstream analysis.

Cellular ultrastructure studies
Supports preservation of membranes, organelles, and protein architecture in research applications.

Laboratory fixation workflows
Suitable for protocols requiring consistent, reproducible aldehyde-based fixation.

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Functional Role

Karnovsky’s Fixative functions as a crosslinking fixation system that stabilizes biological structures through aldehyde-mediated protein crosslinking. Formaldehyde penetrates tissue rapidly, while glutaraldehyde provides stronger crosslinking, resulting in improved preservation of fine cellular detail.

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Why Use Karnovsky’s Fixative?

This formulation is widely used when both penetration and structural preservation are required. Compared to single-component fixatives, the combination of aldehydes provides a more balanced fixation profile, particularly for applications involving electron microscopy and ultrastructural analysis.

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Handling & Storage

• Store components according to label instructions.
• Prepare working solution using provided kit components.
• Store prepared solution at 4°C for up to 6 months.
• Handle with appropriate safety precautions and PPE.
• Consult the SDS for detailed handling and safety information.

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FAQ

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What is Karnovsky’s Fixative used for?

It is used for fixation of biological specimens in electron microscopy and histology to preserve cellular structure.

What makes Karnovsky’s Fixative different?

It combines formaldehyde and glutaraldehyde, providing both rapid penetration and strong crosslinking for improved structural preservation.

How long can the working solution be stored?

The prepared solution can be stored at 4°C for up to 6 months.

Is this suitable for electron microscopy?

Yes. It is commonly used for EM applications where ultrastructural preservation is required.

What buffer is included?

The kit includes a 0.2 M phosphate buffer for preparing the working fixation solution.