The EcoSEC GPC system contains two pumps, a sample pump to deliver sample and solvent through the column, the other pump is designed to flow solvent (via a reference column) to the reference cell of the RI detector. By installing an optional column switching valve and replacing the reference colum with another analytical column, an analysis can be performed on column 1, while equilibrating column 2. After switching the valve, column 2 becomes the measurement column, while column 1 will be in the flow path to the reference cell.
The illustrations below show the sample being transported to column 1, while the reference pump delivers solvent via column 2 to the RI reference cell. After switching the valve, the sample flow is directed to column 2, while column 1 now acts as the reference column. The column switching valve consists of two 4-port valves. In the figure below a simplified schematic with one valve is used to illustrate the principle operation of this optional device.
The optional column switching valve shortens the time needed to perform an analysis of the same sample on, for instance, a low and high MW linear column, or to analyze the same sample on two different column types using a single solvent.
Control of up to 8 columns in the GPC instrument
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