1. Old LC-MS couplings

The many problems associated with the on-line coupling of these two techniques, which can easily be used separately, have long held back the effective development of LC-MS systems. The directions initially taken to circumvent the apparent incompatibility of the two techniques were all abandoned. At one time, they resulted in instruments marketed by all manufacturers, often at very high prices, and are now only of historical interest. These early methodologies are briefly listed here for the record, along with a selection of references for interested readers.