Chromatography is a separation technique where a mobile phase carries a mixture of materials through a stationary packed column. The interaction between the different components of the mixture cause them to move at different speeds through the column and hence exit at different times.

The bulk of ITS’s experience has been built up with column based, liquid chromatography in the biotech sector. Whilst widely used in analytical chemistry, electrical tomography is not well suited to gas phase chromatography (GLC).

There are two main areas of interest – the performance of the column itself (in terms of different packing methods) and the actual separation of particular components of interest.

Column performance has been assessed using several cross-sectional measurement planes. Electrodes are engineered to provide the minimal impact on the column wall. Data from each measurement plane are integrated together to provide a real time view as a step change in conductivity progresses down the column.

In addition to circular planes, ITS has also developed linear arrays which focus on the rate of flow of materials as they progress down the column. This approach assumes a degree of circular symmetry through the plane of the column.

The separation process itself can also be measured. This is best done where there is a significant change in electrical conductivity between the different phases of interest.