Differentiation of isomers of oxygenated polycyclic aromatic hydrocarbons by laser desorption laser post-ionization time-of-flight mass spectrometry

Abstract

Oxygenated polycyclic aromatic hydrocarbons (OPAHs) are mutagenic and ubiquitous pollutants to both humans and environment. Routine analytical methods for differentiating their isomers still remain challenges. In this article, we present laser desorption laser post-ionization time-of-flight mass spectrometry (LDPI-TOFMS) as a new approach for the characterization of isomers of OPAHs. Herein, a pulse laser with the wavelength of 532 nm is used to desorb analytes which are post-ionized by another pulse laser with wavelength of 266 nm. A clear discrimination of quasi-molecular ion peaks and characteristic peaks among OPAHs could be observed. We have demonstrated that LDPI-TOFMS can be used to distinguish isomers quickly and clearly irrespective of the polarity and solubility of samples. Additionally, results from other four mass spectrometry (MS) based methods have also been compared, despite the fact that they were unable to distinguish the isomers or unable to obtain molecular ion peaks. These results suggested the great potential of LDPI-TOFMS platform for ascertain varieties of organic isomers which are not practically distinguished by other MS methods.