## Common ground
Both options are petroleum sulphonates—chemical compounds made by sulphonating petroleum or its fractions.
## Options at a glance
**3402.90 – Water-soluble**
- **Defining trait:** Designed to dissolve in water, typically neutralized with alkali metals, ammonia, or ethanolamines.
- **Typical examples:** Sodium or ammonium petroleum sulphonates used in detergents or emulsifiers.
- **Best fit when:** The product is intended for use in aqueous solutions, such as cleaning agents or oil-in-water emulsions.
**3824.99 – Not water-soluble**
- **Defining trait:** Not neutralized to form water-soluble salts; remains in acidic or partially neutralized form, often used as intermediates or additives.
- **Typical examples:** Raw sulphonated petroleum fractions used in lubricants or as chemical intermediates.
- **Best fit when:** The product is used in non-aqueous systems, such as industrial oils or as a precursor for further processing.
## Key differences
| Feature | 3402.90 (Water-soluble) | 3824.99 (Not water-soluble) |
|-----------------------|--------------------------|------------------------------|
| Solubility in water | Yes | No |
| Neutralization level | High (alkali/amine salts)| Low or partial |
| Primary use | Formulations, detergents | Intermediates, lubricants |
## How to choose
- Is the product designed to dissolve in water? → 3402.90
- Is it used in oil-based systems or as a raw material? → 3824.99
## Overlaps & pitfalls
A product may appear to fit both if it’s partially neutralized. However, solubility is the key differentiator: if it dissolves in water, use 3402.90; otherwise, 3824.99. The main function (final application) should determine the classification—do not prioritize processing method over end-use