Multidimensional high performance liquid chromatography

While LC x LC separations are not conventional with respect to hyphenated methods of analysis, they do in fact serve that purpose. Selectivity changes for complex samples can be monitored using the second dimension as a means to "detect" the changes that take place in the first dimension. This allows the analyst to develop separation protocols for complex samples that truly reflect the characteristics of the sample, rather than being based on a set of model compounds, which may or may not adequately represent the real sample. Furthermore, the high peak capacity of a 2D system allows for chemical signatures to be obtained. These signatures are readily achieved without the need for more complex hyphenated methods of analysis, and could be used as a first step in the classification of the sample, perhaps then limiting the number of samples that require further, more detailed hyphenated methods of analysis. This would greatly reduce the cost and speed in the analysis of complex samples. This type of analysis is ideally suited to the needs of the analyst who also requires that key sample components be extracted and collected from the more complex native sample.