HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY MASS-SPECTROMETRY OF PORPHYRINS BY USING AN ATMOSPHERIC-PRESSURE INTERFACE

A method is described for the high-performance liquid chromatography ( HPLC) mass spectrometry analysis of porphyrin mixtures by using an atm ospheric pressure interface, which can operate in two modes: pneumatic ally assisted electrospray and atmospheric pressure chemical ionizatio n (APCI). Optimization of the conditions and evaluation of spectral in formation has been carried out by using direct injection of free-base and metallo porphyrin standards. The most effective results were obtai ned using APCI. HPLC-APCI mass spectrometry analysis of the demetallat ed vanadyl porphyrin fraction from the Triassic Serpiano oil shale has allowed rapid characterization of the distribution; more than 50 sign ificant components are present. The presence of trace amounts of high molecular weight (> C-33) cycloalkano porphyrins indicates the occurre nce of photic zone anoxia in the ancient water column. This example il lustrates the potential of the approach for studies of porphyrin mixtu res of environmental or biological significance, which should be appli cable to other types of metallo and free-base components that can be s eparated by HPLC under normal or reversed-phase conditions.