Frequently Asked Questions

Human Blood Products

How is Pel-Freez Biologicals’ antibody-depleted complement made?

We have developed a proprietary process for antibody removal based on affinity chromatography. Our method results in low residual antibody (<3% vs. feed serum) while maintaining high complement potency.

What’s the difference between Pel-Freez Biologicals’ antibody depleted human complement (ADHC) and antibody depleted human serum (ADHS)?

ADHC retains high complement potency for use in assays requiring functional complement activity. ADHS is devoid of complement activity due to heat-inactivation and thus can be used in applications requiring serum components other than complement, e.g. a negative matrix for dilution, preparation of QC samples, or cell culture applications where a nutrient source is need but complement function could inhibit cell growth.

Animal Blood Products

What’s the maximum lot size of animal blood products I can order?

Our typical animal blood product lot sizes range from 50 L to 200 L.

How are your sterile-filtered products made?

Sterile-filtered products are manufactured using a combination of pre-filtration steps optimized for each product and final filtration using 0.2 micron filters.

Do you have processes in place for the proper segregation of animal-based products obtained from different species?

Yes, we maintain proper segregation of animal-based products, in accordance with Regulation (EC) 1069/2009 and Regulation (EU) 142/2011. Our facility is inspected by USDA APHIS to ensure compliance.

What is the anticoagulant ratio for whole bloods and plasmas?

Typical anticoagulant ratios are 9 parts blood to 1 part anticoagulant. Specific ratios are provided in the Product Datasheets and Certificates of Analysis for each product where applicable.

What is the shelf life of whole bloods?

For applications demanding fresh whole blood, we recommend usage within 5-7 days or as soon as possible after delivery. These products may be suitable for a longer period in other applications with less stringent requirements, though we suggest usage within 30 days of delivery.

Should I freeze whole bloods?

Generally, we do not recommend freezing whole bloods as the freeze-thaw process will result in red blood cell lysis. However, certain applications may call for freezing or other treatment of whole bloods or any of our other products. Our products are meant to serve as raw materials or intermediates and therefore may be used in a wide variety of end use applications.

Are blood products aseptically collected?

Yes, depending on the species and collection environment, aseptic collection techniques are practiced whenever possible. In animal collection facilities where aseptic technique may not be feasible, materials are collected as carefully as possible by highly trained technicians. Animal blood products are collected in a abattoir environment.

What buffer should I use to reconstitute gamma globulin?

The protein is more readily soluble in a saline solution. It is generally recommended to reconstitute in at least 0.2% NaCl solution BUT, each end-user must determine if that is appropriate for their application.

Animal Tissues/Extracts

Are tissues collected from a USDA-inspected abattoir?

Yes, our rabbit tissues are collected from our Rogers, AR rabbit processing facility, where a USDA inspector remains on site at all times during processing. Each rabbit processed is inspected and any by-products collected are discarded should any animal be found to be unfit for human consumption or otherwise unsuitable for use.

What is the difference between item 41110 and 41170 rabbit brain acetone powders?

Each of these rabbit brain acetone powders begins with a frozen rabbit brain as the raw material prior to acetone drying and powder production. Code 41170 includes barium sulfate during processing while code 41110 does not. Barium sulfate acts to bind clotting factors which may speed coagulation, thus code 41170 has increased sensitivity to clotting deficiencies.


What are the typical dilutions for your Tyrosine Hydroxylase antibodies, such as western blot, ELISA, formalin-fixed paraffin embedded tissue, etc.

A typical starting dilution for antibodies in immunoassays is 1:1000. Consider adjusting the dilution depending on your experimental conditions, to increase or decrease the signal-to-noise ratio, etc.

Should I store antibodies at -20 C or at -80 C? Should I aliquot them upon delivery?

Either - 20 C or - 80 C is acceptable depending on the usage, however, avoid multiple freeze-thaw cycles. Our antibodies contain glycerol which will inhibit freezing at -20 C, however, the materials will freeze at -80 C. If the antibody will be consumed within a few weeks of delivery, we recommend storage at -20 C. For long term storage, we recommend subaliquoting in single-use aliquots then storing at -80 C.


Do you offer products collected from diseased humans or animals?

Not at this time. Please contact us if you are interested in a particular product as we work with a network of suppliers and may be able to find a solution for you.

Why don’t I see an expiration date on my product?

Our products are used in a wide variety of applications - many of which are difficult for us to replicate in our laboratories. Thus we cannot test for stability in all of the applications in which our products may be used. We do perform an extensive battery of QC tests on all of our products to ensure adherence to standard biological parameters important for each product category.

Do you perform COVID testing of your products? Is it possible that the lots mentioned below are derived from COVID-19+ donors, and if this could pose a health risk for our laboratory staff?

Not at this time. We currently source all raw materials that would be susceptible to COVID-19 from suppliers that follow FDA guidelines. For more information, please visit We recommend following universal precautions to further reduce health risks.

About Pel-Freez Biologicals

Pel-Freez Biologicals produces high quality raw materials and intermediates for biological research and diagnostic manufacturing. Our products include lyophilized tissue powders, normal rabbit serum and serum products from other species including: human serum, human plasma, blood complement, tissues, antibodies, and other biological raw materials.