Distilled Water is water that has been purified through the process of distillation.This process removes impurities, minerals, salts, and microorganisms, leaving behind pure H₂O molecules.
How is distilled water made?
- Boiling – Water is heated until it becomes steam.
- Condensation – The steam is collected and cooled back into liquid form.
- Collection – The resulting water is free from most contaminants.
Why Distilled water is commonly used in Quality Control (QC) testing?
- It has high purity and consistency.
- Neutral pH (around 7) if freshly distilled, but can absorb CO₂ from the air over time, making it slightly acidic.
- Conductivity is very low, since it lacks ions.
- Free from Impurities: Distilled water is free from ions, minerals, organic contaminants, and microorganisms that can interfere with analytical results.
- Consistent Results: The absence of impurities ensures that test results are reliable and not influenced by unknown variables from water contaminants.
- Avoid Chemical Reactions: Regular water (like tap water) contains ions (such as calcium, chloride, and iron) that can react with reagents or samples, affecting test accuracy.
- Instrument Protection: QC instruments like HPLC, UV spectrophotometers, and others require pure water to prevent blockages, corrosion, and contamination.
- Compliance: Regulatory guidelines (such as pharmacopeias like IP, USP, EP, or BP) often specify the use of purified water types (distilled, deionized, or water for injection) to ensure reproducibility and accuracy.
In distilled water, these H₂O molecules are the same as in normal water, but without any other dissolved substances (like salts or gases). It’s just pure clusters of H₂O molecules interacting through hydrogen bonds. In short, distilled water minimizes external variables and maintains the integrity of QC testing.
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Resource Person: Susmita