Microchip Atmospheric Pressure Photoionization for Analysis of Petroleum by Fourier Transform Ion Cyclotron Resonance Mass Spectrometry

Atmospheric pressure photoionization (APPI) Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) has significantly contributed to the molecular speciation of petroleum. However, a typical APPI source operates at 50 microL/min flow rate and thus causes a considerable mass load to the mass spectrometer. The recently introduced microchip APPI (microAPPI) operates at much lower flow rates (0.05-10 microL/min) providing decreased mass load and therefore decreased contamination in analysis of petroleum by FT-ICR MS. In spite of the 25 times lower flow rate, the signal response with microAPPI was only 40% lower than with a conventional APPI source. It was also shown that microAPPI provides very efficient vaporization of higher molecular weight components in petroleum analysis.