FLEXIBLE OFF-LINE LC-IR INTERFACING BY MICRO-COLUMN SWITCHING AND ADDITION OF A MAKE-UP LIQUID

The versatility of a spray-jet LC-IR interface has been improved by ap plication of capillary liquid chromatography combined with post-column addition of methanol as a make-up liquid. Fluctuations in the evapora tion profile are minimized, which facilitates gradient elution includi ng high percentages of water. Microcolumn switching has been applied t o allow the introduction of large sample volumes, thus improving the l imit of detection. The current performance of the interface is demonst rated by the results for the separation and structure elucidation of m etabolites of pyrene in an in-vitro microsomally treated sample.