Electrospray ionization mass spectrometric detection of low polar compounds by adding NaAuCl 4

Liquid chromatography electrospray ionization mass spectrometry (LC/ESI/MS) has been widely used for various analyses. However, it is difficult to use LC/ESI/MS for the analysis of low polar compounds, such as polycyclic aromatic hydrocarbons. It is well known that AuCl 4 − ion decomposes to AuCl 3 by heating, and AuCl 3 is a strong π‐electrophilic Lewis acid. Low polar compounds (pyrene, benzo[ a ]pyrene, perylene, benzo[ ghi ]perylene, dibenzothiophene and p ‐dimethoxybenzene) were detected by ESI/MS in the positive ion mode by adding NaAuCl 4 . The low polar compound interacts with AuCl 3 formed at the ESI interface, and undergoes electron transfer to AuCl 3 . The radical cation of the low polar compound was then detected by MS. In addition, the LC/ESI/MS determination of polycyclic aromatic hydrocarbons by the post‐column addition of NaAuCl 4 was studied. © 2016 The Authors Journal of Mass Spectrometry Published by John Wiley & Sons Ltd