Development of a Sheathless Interface between Reversed-Phase Capillary HPLC and ICPMS via a Microflow Total Consumption Nebulizer for Selenopeptide Mapping

A sheathless interface based on a total consumption micronebulizer operating at flow rates in the range 0.5-7.5 (mu)L min^-1 was developed between capillary HPLC and ICPMS. It allowed the efficient nebulization and transport into the plasma of mobile phases containing up to 100% organic solvent without either cooling the spray chamber or oxygen addition. The coupled system was applied to selenopeptide mapping in a protein fraction isolated from a selenized yeast extract. The detection limits were 150 (80Se) and 200 fg (82Se) for a quadrupole instrument with and without a collision cell, respectively, which is a factor 100-150 less than that reported elsewhere for HPLC-ICPMS. The minimal peak broadening (~5 s at the half-height) allowed baseline resolution of a mixture containing more than 30 selenopeptides, many of which could not be separated using the conventional HPLC-ICPMS coupling.