Purified Water (PW) and Deionized Water (DI Water) are related but not exactly the same, although Deionized Water can be considered a type of Purified Water in pharmacopoeial terms.
Purified Water (PW) as per IP is water that meets specific quality standards, regardless of the method used to produce it. It can be made by:
1. Distillation
2. Deionization (Ion Exchange)
3. Reverse Osmosis (RO)
4. Other suitable purification methods.
Deionized Water (DI Water) is water that has been specifically purified through ion exchange resins to remove ions (salts and minerals) –
1. Cation exchange resin: Removes positive ions (like calcium, magnesium, sodium).
2. Anion exchange resin: Removes negative ions (like chloride, sulfate, nitrate).
This process doesn’t remove all impurities—microorganisms, organic compounds, and particles may still be present unless additional purification steps are used (like filtration or UV treatment).
In simple terms all Deionized Water is Purified Water if it meets IP standards for Purified Water.But not all Purified Water is necessarily Deionized Water, because PW can also be produced by other methods (like RO or distillation).
Notes for DI Water in Pharma Use:
1. If you generate Deionized Water through ion exchange, it must pass all the IP tests to be called Purified Water in pharmaceutical use.
2. DI water systems must be validated and regularly monitored to ensure ongoing compliance.
3. DI water is not suitable for injections (for that, Water for Injection – WFI is required).
Key Point (Pharma perspective):
When IP refers to Purified Water, it’s about the quality and specifications, not the production method. So, if your deionized water meets IP Purified Water specifications, you can call it Purified Water for pharmaceutical purposes.
Related Topics:
| Biosimilar vs. Bioequivalence | Sterilization vs. Depyrogenation | QC vs. QA |
| Bioavailability | Biotechnology | Bioinformatics |
Resource Person: Susmita