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NeuroScience Associates

Perfusion Fix Solutions


High quality perfusion fix solutions yield high quality results. Commercially available formaldehyde solutions are NOT fresh and usually have added ingredients to stabilize the solution for long shelf life. This should be considered a “technical grade” perfusion fix solution. Such solutions should only be used for standard, routine, classical stains. However, even these stains may be optimized by having a freshly prepared perfusion solution using reagent grade components.

Preferred Perfusion Fix Solution

Phosphate-Buffered Paraformaldehyde:


Order from EM Sciences, call (215) 412-8400; catalog # 1224SK.
Prepare in the lab:

 For 1000 ml TotalFor 2000 ml TotalFor 4000 ml TotalFinal %
Paraformaldehyde40 g80 g160 g4%
Phosphate Buffer
0.2M; pH 7.2
500 ml1000 ml2000 ml--
Note: Not to be used for the purpose of cryoprotection
40 g80 g160 g4%

For 1000 ml Total:

  1. Begin with 500 ml of dH20 and heat to 60°-65°C (~104° F) on a heater/ magnetic stirrer.
  2. Add the sucrose. Please note: Sucrose is optional and this solution is not to be used for cryoprotection.
  3. Create a deep vortex using a magnetic stirrer bar. Gradually sprinkle the finely powdered paraformaldehyde onto the vortex surface. The solution will be quite milky.
  4. Allow to cool to room temperature
  5. Bring the total volume to 1000 ml with 0.2M Phosphate Buffer and verify the pH.
  6. Filter the solution using a qualitative paper.

For more information:

Antigen Preserve (AP) Solution

Mounting Solutions

Post-Fixative (Storage) Buffer Solutions


Contact Technical Support at NSA Labs via this form or call 865.675.2245 for shipping and preparation questions.

COVID-19 IMPACT: Our labs are currently OPEN for business. We are fully operational with uninterrupted delivery services ready to receive your tissue.


For clients with projects in process: NSA will communicate with you prior to shipping materials to ensure you are able to accept deliveries. If you are unable to receive deliveries due to the current global situation, NSA will hold shipments at our facility until your delivery system returns to normal. If you have not added digital imaging to your order but need it to expedite or continue your research, contact us right away so we can work together to meet your needs.

For clients with tissues, sections and/or slides located at our facility: Please allow us to help you continue your research, particularly if you are working remotely. We are able to perform additional stains, digitize slides for secure remote viewing, and perform additional analysis. Contact us today via email at or using our contact form.

For new clients: We are ready to assist you with all of your neurohistology needs. We are open and fully operational with uninterrupted delivery services ready to receive your tissue.. This is a dynamic situation and we will update this message as things change.

NSA strives to minimize the impact of this global situation on your research and the neuroscience community as a whole. We wish you and yours the best as we maneuver through uncharted waters. Please contact us if we can assist you in any way.