## Common ground
Both options refer to soda lime—a mixture of calcium hydroxide and sodium hydroxide—used primarily for absorbing carbon dioxide.
## Options at a glance
**3822.19 – Laboratory reagent**
- **Defining trait:** Sold in standard quantities for general lab use, not specially formulated for medical or closed-system applications.
- **Typical examples:** Soda lime in bottles for gas purification in chemistry labs.
- **Best fit when:** Used in non-medical, research, or educational settings where CO₂ absorption is needed but not in life-support systems.
**3824.99 – Medical/industrial absorbent**
- **Defining trait:** Specifically prepared by impregnating lime with NaOH for high-efficiency CO₂ absorption in closed environments like anesthesia circuits or submarines.
- **Typical examples:** Anesthesia canisters, rebreather systems in diving or space suits.
- **Best fit when:** Used in medical devices, breathing apparatus, or confined environments requiring reliable, continuous CO₂ removal.
## Key differences
| Feature | 3822.19 – Lab reagent | 3824.99 – Medical/industrial absorbent |
|-----------------------|------------------------------|------------------------------------------|
| Primary use | General lab gas purification | Life-support or closed-system breathing |
| Formulation specificity | Standard mix | Impregnated with NaOH for enhanced absorption |
| Environment | Open, non-critical | Sealed, safety-critical (e.g., surgery) |
## How to choose
- Is it used in a medical device like an anesthesia machine? → 3824.99
- Is it sold in standard lab bottles for general chemical use? → 3822.19
## Overlaps & pitfalls
A product may fit both if it’s used in labs but also has medical-grade formulation—however, **the main function determines the code**. If the product is marketed or designed for medical/industrial breathing systems (e.g., labeled for anesthesia), use 3824.99. Otherwise, use 3822.19. Do not assume that all soda lime is medical-grade