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Frequently Asked Questions

Which skin sensitisation test do I need?

Current regulatory guidance for in vitro skin sensitisation testing is to adopt the “2 out of 3” approach, whereby 2 positive results out of the 3 tests (OECD TGs 442c, 442d and 442e) results in classification as a Skin Sensitiser. If you perform two of the tests and get matching results, this strategy states you can have confidence in the result without the third test. If they have different results, proceed to the third method to find a definitive result. Each of the three methods has different requirements regarding the solubility of your test item, so contact us to find out which will be best for you. You can also read more about the test methods here.

What units is antioxidant activity measured in for this assay?

XCellR8’s antioxidant test uses the OxiSelect™ method. The test is based on the intracellular conversion of DCFH to its fluorescentmetabolite (DCF). The reaction is inhibited by anti-oxidants, reducing the amount of fluorescence observed and so the test measures fluorescent intensity. You can read more information about OxiSelect™ here.

What is an assay?

Broadly speaking, assay is a scientific term that means test. It is often used by the pharmaceutical industry to describe the experimental procedure that quantitatively or qualitatively measures the presence, amount, or functional activity of a target entity (to get all Wikipedia about it!)

Where do you get your human cell cultures from?

We have long standing relationships with global biotechnology companies who we buy our tissue models from. They source them from consenting donors, usually as a by-product of cosmetic surgery.

Why do you need to know the purity of my test item?

Noting the purity of the item being tested is part of our GLP (Good Laboratory Practice) compliance. For certain tests, it allows us to ensure the correct concentration is being tested. It’s also another piece of key information that we check to make sure we have the right test item, and you get the right result.

Why do I need to provide an expiry date or a retest date for my sample?

We ask for an expiry or retest date to ensure that your test item is within its established shelf life specifications when stored under defined conditions – it’s all part of our work being performed in line with GLP (Good Laboratory Practice). It’s important that this is a true expiry date or retest date as it helps us make sure your test item is behaving as it should, and the results you get from us are correct.