Ask a Scientist:
Why Should I Read the Certificate of Analysis?

ask a scientist

ask a scientistStudying the Certificate of Analysis is a fundamental step to ensuring the immune cell products you purchase are going to be viable, pure, or match the specifications required for your experiment.

Let’s face it: even the best purification methods sometimes fail. As a researcher, you need to educate yourself on the purity of the cells before you buy and know what other cell types might be in the vial at a low percentage so you can make an informed purchase.

You can gather a lot of valuable information from a Certificate of Analysis with just a quick glance. It can verify key traits of the cells and the donors, such as:

  • Number of live cells per vial
  • Percentage of viable cells
  • Expression of cell surface antigens (types of cells in the vial)
  • Cell purity
  • Donor age
  • Donor gender
  • Donor race
  • Donor height
  • Donor weight
  • Donor blood type
  • Donor HLA type

As an immunologist, scientist or clinical researcher, you want to be sure the human immune cells you purchase are appropriate for your experiments by following these three tips:

3 Tips for Reading a Certificate of Analysis

1. Always check the viability.

Some vendors may report the total cell number, but cell counts reported on our Certificates of Analysis are always the number of live cells recovered from the vial after thawing. Viability of cryopreserved cells isolated from peripheral blood should be 85% or more. If the viability is lower, the cells may have been handled poorly or isolated a day after collection. Other cell types may have lower viability, but it is still a good indicator of cell quality.

Cells with high viability should behave similarly to this:

Astarte Donor Graph
This chart was created by one of our customers to demonstrate the high viability of our cells and the consistency from vial to vial.

2. Don’t skip the data plots – they contain valuable information.

Looking for more data on the antigen percentages typically supplied on page 1 of the Certificate of Analysis? The 3D data plots, typically found on page 2, provide a great deal more information. If you aren’t sure how to read the plots, it’s simple:

  • The x-axis has one surface characteristic, usually staining with a FITC labeled antibody.
  • The y-axis has a second surface characteristic, usually staining with a phycoerythrin labeled antibody.
  • Color is the third dimension and indicates the number of cells.

The example below shows that this batch of PBMC has 61% T cells and 8.5% B cells. The T cells stain with the CD3 antibody (x-axis) and the B cells stain with the CD19 antibody (y-axis), but there are no cells that express both CD3 and CD19. Another 30% of the cells are neither B cells nor T cells, but are probably monocytes and some NK cells.

CD19PE

3. Check for a “Lot Specific” Certificate of Analysis

Some vendors try to get away with generic Certificates of Analysis that contain their best guess at what is in the vial. Don’t settle for this. Instead, check the Certificate of Analysis to ensure it is “lot specific” meaning the data is relevant to the cells you are purchasing. Look for the lot number somewhere on the document, usually at the top of each page:
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