HPLC cassettes--a new modular separation system with high flexibility.

: A new HPLC system is described wherein the column is used in the form of a cassette. The system includes a novel, problem-free column connection technique (needle seal). The column is not fitted with the usual single inlet and single outlet, but with a system of four combined inlets/outlets. These features provide on the one hand simple operation (e.g., rapid column exchange--no tools needed) and increased performance (e.g., no loss of separating power in the ancillary equipment), and on the other hand, a high degree of flexibility (e.g., convenient column backflush, improved sample splitting, simple eluate splitting, elegant post-column derivatization, and easy column switching).