Conductivity test in the Pharmaceutical Industry

In the pharmaceutical industry, water conductivity is a measurement of the amount of dissolved ions in a water sample, and is used to determine the purity of water.

Using a conductivity meter to measure the conductivity of water sample. The meter applies a voltage across two electrodes immersed in the water, and the resulting current flow is measured, which is directly related to the conductivity of the water.

Procedure:
▪️Rinse the conductivity probe with purified water between measurements to prevent contamination.
▪️Immerse the probe into the water sample, ensuring it’s fully submerged and not touching the sides or bottom of the container.
▪️Allow the reading on the conductivity meter to stabilize before recording.
▪️Record the conductivity measurement for each sample.

The conductivity of pharmaceutical grade water should be less than 1.3 microSiemens per centimeter (uS/cm), and should be checked throughout the purification process to ensure it is free of contaminants.

While pure water conducts electricity poorly, water that has certain chemicals or elements in it, and at varying amounts—including sodium, magnesium, calcium, and chloride—is a better conductor of electricity.

water salinity increases, conductivity increases alongside it. Water that’s warmer also tends to have more conductivity.

The conductivity of water can vary depending on its source.

For example, river water typically has a conductivity of 100–2000 uS/cm, while seawater has a conductivity of 45–72 mS/cm.

The conductivity of drinking water should be less than 1 milliSiemens per centimeter (mS/cm).

According to the USP, the conductivity limit for water for injection (WFI) at 25°C should be less than 1.3 uS/cm.

Type I lab water, which is considered “ultrapure”, should have a conductivity of less than 0.056 uS/cm.

Temperature can directly impact the conductivity of any liquid. Conductivity can usually be reduced by minimizing ionic impurities in water.

conductivity is used as a measurement of the purity of the water and its checking in pharma- grade water is a control measure.

USP <645> WATER CONDUCTIVITY

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