用自动化ESI-FT-ICR质谱进行石油分析

Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (FT-ICR MS) offers both high resolution (>400,000) and high mass accuracy (<500 ppb) that make it uniquely suited for complex mixture analysis. In the past we have shown that it can provide detailed compositional information (at the level of unambiguous molecular formula assignment) for a wide range of petroleum samples ranging from gasoline to asphaltenes and atmospheric residuals. However, its success has generated a problem. As FT-ICR MS becomes an important tool for compositional analysis of complex petroleum samples, sample throughput quickly becomes a limitation that must be addressed.

 

Here, we present the latest results that enable automated/unattended/remote FT-ICR MS data collection for complex petroleum samples. Automation of the ESI process is achieved with an Advion NanoMate robot coupled to a PREDATOR data station with TCL scripts. For extended automation runs, evaporative loss of the volatile ESI solvent system (comprised mostly of toluene and methanol) is a concern. Additionally, the Advion Nanomate system can draw only 15   L of sample into the polymer-based spray tip. Consequently, if extended ESI spray periods are required, multiple sealed sample compartments must be available for subsequent  analysis  (because  once  pierced,  the  original compartment  will  suffer  from unwanted evaporative loss). Therefore the sample holder must both minimize/eliminate evaporative loss and provide multiple sealed wells for additional sample introduction (if required). For this reason, the ten petroleum samples were each placed in three glass wells (approximately 200   L per well--more could be used if required) and sealed with aluminum foil by an in-house designed clamp. Importantly, all samples displayed no evaporative loss after 22 hours in the foil-sealed 96 well glass plate. The samples were sequentially introduced by positive-ion ESI, and 100 scans were collected for each well. Potential carryover is eliminated because the Advion NanoMate system supplies a new spray tip and nozzle for each petroleum sample.