Fast liquid chromatography/electrochemistry/mass spectrometry of ferrocenecarboxylic acid esters

Rapid liquid chromatographic separations of ferrocenecarboxylic esters of various alcohols and phenols have been achieved on reversed-phase columns of 20 mm length. After separation, the ferrocene derivatives are oxidized electrochemically under formation of the charged ferrocinium species, which are easily detected by mass spectrometry using an atmospheric pressure chemical ionization source operated in the heated nebulizer mode. While a series of nine phenol derivatives was separated within less than 1.5 min, six alcohol derivatives eluted within 1 min. Limits of detection using a single quadrupole mass analyzer ranged from 60 to 190 nmol/l. Additional work was directed on the use of a graphite in-line filter instead of a silica-based reversed-phase column to achieve the separation.