When this test applies
Chemical characterisation is how endpoints get addressed with data rather than with animals under ISO 10993-1:2025. This particular arm is one cell of a grid — volatility on one axis, solvent polarity on the other. It targets the heavy end — larger oligomers, non-volatile antioxidant degradants, colourants and anything that would decompose rather than elute on a GC column, and in n-hexane specifically it is hydrocarbons and mineral oils, slip agents and lubricants such as erucamide and metal stearates, phthalate and adipate plasticisers, non-polar antioxidants and their degradants, and waxes that come out. Hexane is the non-polar extreme, and it is what demonstrates the lipophilic end of the profile has actually been looked for — a common gap in submissions.
When to run it
Early, and commissioned as a solvent set rather than one arm at a time — the same extraction campaign supports all of them, and a partial profile usually has to be repeated. Before any of it, get the protocol and the analytical evaluation threshold agreed (GRK-2005): an AET set too high means the study missed things it should have found, and that is a finding a reviewer makes, not you.
What the result gives you
A GLP report giving each recovered compound identified and semi-quantified against its reporting limit, by liquid chromatography rather than gas, with the extraction conditions documented. If your own toxicologist writes the assessment, this is the dataset they need and the documentation trail a reviewer asks for. If you would rather we reached the conclusion, the ISO 10993-17 assessment (GRK-2001) is the next line item.
What it does not settle
HPLC/MS is the arm for the heavy end, and its identifications are typically less definitive than GC/MS library matches — an unknown here often needs follow-up work to name. Hexane recovers essentially nothing polar, and it wets polar polymers poorly, so on a hydrophilic material it can under-recover across the board. A clean hexane result on a polar substrate says less than it appears to. And chemical characterisation has no independent pass or fail at all: compounds are reported against analytical reporting limits, not against a safety threshold, so the judgment about patient safety is made in the ISO 10993-17 assessment rather than here.
Method
Testing per ISO 10993-18:2020/Amd 1:2022. A single extract is prepared in n-hexane at 10 mL, with the extraction ratio per ISO 10993-12: 6 cm²/mL for material under 0.5 mm thick, 3 cm²/mL at 0.5 mm or thicker, or 0.1 to 0.2 g/mL where surface area is indeterminate. The extract is analysed by HPLC/MS.
Where it runs
This analysis is subcontracted to an ISO/IEC 17025 accredited, GLP certified laboratory, and the report is issued under Groenakker cover, in Groenakker’s report template or in your document template on request at no extra cost. Turnaround is 4 to 5 weeks.
Usually ordered alongside
The semi-volatile arm in hexane, and the water and IPA non-volatile arms. Consider gravimetric residue in hexane too, as a mass-balance check on how much this arm actually accounted for. And — critically — an ISO 10993-17 toxicological risk assessment to interpret the numbers. Chemistry without the assessment is data without a conclusion; ChemTox bundles the two.
