One CAS Number Can Cover Several Commercial Grades
Industrial and analytical n-Heptane share CAS 142-82-5, but their acceptance criteria and documentation differ. Industrial solvent users may prioritize assay, boiling range, benzene, sulfur and commercial packaging. Laboratories may require much tighter controls for water, evaporation residue, UV absorbance and instrument suitability.
Why Purity Is Not Enough
A product labeled 99% can still be unsuitable for chromatography if trace absorbers or non-volatile material interfere with analysis. Conversely, an industrial process may not benefit from paying for analytical controls that do not affect its outcome. Grade selection should follow the application.
Questions for Supplier Qualification
- Is the quoted value actual n-Heptane or total hydrocarbons?
- Which test method supports the assay?
- Are water and residue controlled?
- Is UV or chromatography suitability tested?
- Is the packaging appropriate for the required cleanliness?
Thermo Fisher specifications illustrate how analytical grades separately control water, residue and other analytical parameters. Xinchen’s standard listing is an industrial n-Heptane grade unless another specification is expressly confirmed.
Safety note: Every grade remains a highly flammable solvent and requires SDS-based handling.