Sample Enrichment and Sample Cleanup (2-Position/6-Port or 2-Position/10-Port Valves)

Advantages:

Easy automation of sample preparation
Higher reproducibility
Increased productivity and sensitivity

Sample cleanup is essential for samples with complex matrices, such as food extracts and waste water. Before injection into a LC or LC/MS system, the sample matrix must be separated from the analytes of interest. Otherwise, contaminants can disrupt separation and detection or even damage the analytical column.

Enrichment Methods

Enrichment methods are the techniques of choice to obtain highest sensitivity and to remove the sample matrix. The analytes are retained and concentrated onto the precolumn, while the sample matrix is passed to waste. After the valve switch, a second pump backflushes the analytes out of the precolumn onto the separation column. This allows injection of large volumes onto the precolumn, significantly expanding sensitivity in the range of ten to several thousands.

Sample Cleanup

Cleanup methods handle analytes and matrices in the opposite way to enrichment methods. Matrix components are retained on the precolumn while the analytes pass through to the separation column. After the valve switches, an extra pump backflushes the matrix components out of the precolumn to waste, while the analytes are separated on the main column. Backflushing prepares the precolumn for the next injection.