# Reagents and high-purity lab chemicals: Characteristics

Why labs refuse to switch grades once results depend on them

Source page: https://www.materialinsights.org/chemicals/lab_reagents/characteristics/

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)

## Other sections

- [Summary](https://www.materialinsights.org/chemicals/lab_reagents/index.md)
- [Overview](https://www.materialinsights.org/chemicals/lab_reagents/overview/index.md)
- [Correlation](https://www.materialinsights.org/chemicals/lab_reagents/correlation/index.md)
- [Production route](https://www.materialinsights.org/chemicals/lab_reagents/routes/index.md)
- [Production](https://www.materialinsights.org/chemicals/lab_reagents/production/index.md)
- [Feedstocks](https://www.materialinsights.org/chemicals/lab_reagents/feedstocks/index.md)
- [Cycles](https://www.materialinsights.org/chemicals/lab_reagents/cycles/index.md)
- [Trading](https://www.materialinsights.org/chemicals/lab_reagents/trading/index.md)
- [Movement](https://www.materialinsights.org/chemicals/lab_reagents/movement/index.md)
- [Regulation](https://www.materialinsights.org/chemicals/lab_reagents/regulation/index.md)
- [Emissions](https://www.materialinsights.org/chemicals/lab_reagents/emissions/index.md)
- [Relationships](https://www.materialinsights.org/chemicals/lab_reagents/links/index.md)