When this test applies
ISO 10993-1:2025 makes chemical characterisation to ISO 10993-18 the starting point of a biological evaluation for prolonged and long-term contact devices, and the preferred route to the systemic, genotoxicity and carcinogenicity endpoints wherever good extractables data can replace an animal study. Non-volatile residue is the mass-balance check on the extraction: it says how much came out in n-hexane, independent of what the compounds are, and it is the quantity the exhaustive-extraction stopping rule in ISO 10993-18 is written against.
When to run it
At the start of an exhaustive-extraction programme, and alongside the compound-specific screens in the same solvent. A high NVR with a short compound list is the signal that the screens are missing something and the method needs attention.
What the result tells you
The mass of residue left after the n-hexane extract is evaporated, reported per device or per unit area. Under the ISO 10993-18 stopping rule, extraction continues until a step yields no more than 10% of the residue recovered in the first. There is no independent pass or fail.
What it does not tell you
Nothing about what the residue is — identification and quantification are the job of the VOC, SVOC and NVOC screens — and nothing about volatiles, which are lost on evaporation. Chemical characterisation has no independent pass or fail: the data mean nothing until a toxicologist reads them against exposure under ISO 10993-17, and the screen cannot see compounds the solvent did not extract or the technique cannot detect.
Method
Testing per ISO 10993-18:2020/Amd 1:2022. The sample is extracted in n-hexane, the extract is evaporated to dryness under controlled conditions and the residue is weighed on an analytical balance against a solvent blank. Extraction ratio follows 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.
Where it runs
Testing is performed to Groenakker protocols at an ISO/IEC 17025 accredited laboratory in Groenakker’s network, and the report is issued under Groenakker’s ISO 13485:2016 certified quality system, in Groenakker’s report template or in your document template on request at no extra cost.
Usually ordered alongside
The other screens that make up a complete extractables profile — VOC, SVOC, NVOC and heavy metals across the three solvents — then the toxicological risk assessment (GRK-2001) that turns the compound list into a conclusion. The ChemTox packages bundle all of this for one price.
