Formation of Artifacts from Simple Phenolic Compounds in SFC-UV-(HR)MS

In this study, we present the formation of artifacts from simple phenolic compounds and derivatives in SFC-UV-MS analysis. These ions were detected only when the UV detector was turned on, demonstrating that UV light is necessary for their formation. Based on high-resolution mass spectrometry (HRMS) analysis of 21 standards in negative electrospray ionization mode, the artifacts were annotated as ions where CO₂ or NO₂ had been added to the molecular ion or to an ion that had lost a functional group. In approximately half of the cases, the MS signal of the artifact was higher than that of the molecular ion. Although the formation of artifacts can complicate nontarget analysis as the detected molecular ion does not match with the analyzed standard, we demonstrated that the phenomenon can aid with the structural identification of isomers due to the formation of specific ions. In addition, the overall MS signal increased when the UV was turned on, which can help with the detection of low-abundance compounds, and one compound─ anisole─ was detected only thanks to the artifact. Thus, the aim of this article is to make researchers aware of the UV effect in SFC-UV-MS analysis together with the advantages and disadvantages of artifact formation.