Reagents and high-purity lab chemicals: Characteristics
Why labs refuse to switch grades once results depend on them
What this tab covers The physical and chemical properties that set its grade, price and uses, with the commercial grades and the standards that define them.Grade is everything: purity, trace metals, UV absorbance, water content and particle levels, all certified per lot. Buyers stay with a qualified grade because changing it can change test results.
Properties that matter commercially
| Property | Value / specification | Why it matters | Source |
|---|---|---|---|
| Assay purity | ACS/AR grades typically at least 99-99.9% (indicative) | analytical accuracy | ACS Reagent Chemicals (indicative) |
| Trace metals | ppb levels for trace-metal grade acids (indicative) | ICP-MS analysis | indicative |
| UV cut-off and residue | HPLC acetonitrile UV cut-off about 190 nm (indicative) | baseline noise in chromatography | indicative |
| Water content | anhydrous solvents below about 50 ppm (indicative) | moisture-sensitive reactions | indicative |
Commercial grades
- Laboratory reagent (LR) and synthesis grade
- Analytical reagent (AR) and ACS grade
- HPLC, LC-MS and spectroscopy grades
- Pharmacopoeia grades (USP, EP, IP)
- Molecular biology grade
- Certified reference materials (ISO 17034)