The Charge Ratio Analysis (CRA) method is an official method used to determine the moisture content of various materials. The CRA method entails the measurement of the electrical properties of the analyzed substance through its ‘dielectric constant’. This method is employed across various industries, including the food, pharmaceutical, and construction sectors.
This technique operates on the basis of the relationship between the moisture content of a substance and its dielectric constant. As moisture infiltrates a substance, it augments the material’s dielectric constant. This is due to moisture’s high polarity, which facilitates the accumulation of electrical charges between its molecules. Consequently, the higher the moisture content, the greater the dielectric constant.
The Charge Ratio Analysis method involves the utilization of a specialized device referred to as a capacitative sensor. The capacitative sensor is introduced into the material under investigation, and the electrical conductivity between the sensor and the material is quantified. The dielectric constant is determined from this conductivity measurement.