DETERMINATION OF HYDROXY POLYCYCLIC AROMATIC-HYDROCARBONS BY LIQUID-CHROMATOGRAPHY MASS-SPECTROMETRY - COMPARISON OF ATMOSPHERIC-PRESSURE CHEMICAL-IONIZATION AND ELECTROSPRAY

Atmospheric pressure chemical ionization (APCI) and pneumatically assi sted electrospray (ESP) mass spectrometry (MS) in both positive and ne gative ionization modes coupled to high-performance liquid chromatogra phy (HPLC) have been used for the characterization of hydroxy polycycl ic aromatic hydrocarbons (hydroxy-PAHs). A series of hydroxy-PAHs were separated using reversed-phase liquid chromatography and their ESP an d APCI spectra were analyzed. Results showed that chemical ionization was the main process in APCI and, in contrast to what happened with ES P, no electrochemical reaction was observed. In order to optimize the response in ESP and to adjust the optimum flow-rate for the coupling o f the HPLC system to the ESP source, the variation of the response ver sus flow-rate and the use of split systems were studied. LC-MS detecti on limits (signal-to-noise ratio 3:1) were determined for APCI and ESP in both ionization modes, ranging from 1.5 to 35 mu g/ml for ESP and from 0.3 to 50 mu g/ml for APCI.