Leachables and extractables - Glossary

Leachables and extractables (E&L) are chemical contaminants that can migrate from contact materials, such as vials, stoppers, or tubing, into a stored product. They come from packaging or equipment, not from the product itself. Because they sit outside the main substance, they may not show up in a basic purity result, but they can still affect safety and efficacy.

E&L Testing Follows a Two-Stage Process

Extractables study: This phase uses aggressive solvents and high temperatures to pull chemicals out of contact materials. It builds a worst-case profile of substances that could migrate from vials, stoppers, or tubing under stress.
Leachables study: This stage tests the actual stored product across its shelf life under normal conditions. It checks which chemicals from the extractables profile actually entered the product during real-world storage.

E&L Matters Beyond a Purity Claim

A standard "99% pure" lab result measures the substance itself, not contaminants from rubber stoppers or plastic vials. Unmonitored leachables can react with the product, change its efficacy, or create toxicological risks that a purity percentage does not capture. Many lab reports for research chemicals omit E&L testing, so a high purity score can still leave unknown exposure from the container.

E&L is different from process-related impurities, such as leftover synthesis reagents, and from degradation products, where the molecule breaks down over time. E&L comes from external packaging and contact materials. Extractables are the theoretical maximum that could leave a material under stress; leachables are the actual contaminants present under normal storage.

E&L Testing Follows a Two-Stage Process

E&L Matters Beyond a Purity Claim

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