1. Karl Fischer Titration (KFT) – Highly Accurate

Principle: Karl Fischer reagent selectively reacts with water, allowing precise quantification.

Procedure:

Extract a known volume of the feed or filtrate.

Inject it into a Karl Fischer titrator.

The instrument measures water content based on the reaction endpoint.

Advantages: Highly precise, suitable for low water concentrations.

2. Dean-Stark Distillation – Best for Higher Water Content

Principle: Uses toluene or xylene to co-distill water from the sample.

Procedure:

Mix a known sample volume with toluene.

Heat in a distillation apparatus; water condenses in a graduated trap.

Measure the collected water volume.

Advantages: Suitable for emulsions with significant water content.

3. Infrared Spectroscopy (FTIR) – Rapid Analysis

Principle: Water has distinct absorption peaks in the IR spectrum.

Procedure:

Develop a calibration curve with known water concentrations.

Scan the sample using an FTIR spectrometer.

Compare absorption peaks to determine water content.

Advantages: Quick, non-destructive.

4. Density and Refractive Index Measurement – Indirect Estimation

Principle: Water presence alters the density and refractive index of the mixture.

Procedure:

Measure the density or refractive index using a densitometer or refractometer.

Compare with reference values for water-oil mixtures.

Advantages: Simple and cost-effective, but less precise.

5. Thermogravimetric Analysis (TGA) – Precise for Small Samples

Principle: Heating the sample evaporates water, and mass loss is measured.

Procedure:

Weigh the sample before and after heating.

The mass difference corresponds to water content.

Advantages: Precise but requires thermal analysis equipment.

Choosing the Best Method

For precise, low-level water detection: Karl Fischer Titration.

For significant water concentrations: Dean-Stark Distillation.

For quick estimation: FTIR or Density Measurements.

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