A new strategy for non-targeted screening of phthalate metabolites using liquid chromatography-high resolution mass spectrometry

Abstract The ubiquity and potential toxicity of phthalates make their exposure on humans a matter of great concern. Measuring the targeted phthalate metabolites using liquid chromatography-tandem mass spectrometry (LC-MS/MS) is a commonly used approach for human biomonitoring of phthalates. However, the targeted LC-MS/MS methods have been unable to meet the desire to comprehensively and rapidly screen and identify for as many known and potentially unknown phthalate metabolites in human samples. Instead, non-targeted screening methods, allowing the rapid detection and identification of unknown compounds in a wide variety of environmental and human samples are complementary to the targeted methods. In this study, 23 phthalate metabolites were analyzed using liquid chromatography-quadrupole time-of-flight mass spectrometry (HPLC-QTOF-MS) for development of a non-targeted screening method. The fragmentation patterns of the 23 phthalate metabolites were investigated using collision-induced dissociation experiments at 10, 20, and 40 eV. And three common specific product ions at m/z 121.0297, m/z 147.0088, and m/z 165.0193 corresponding to C7H5O2-, C8H3O3-, and C8H5O4-, respectively were observed in their mass spectra. Based on the three common product ions, a new strategy was proposed for non-targeted screening of the new phthalate metabolites as exposure biomarkers for human biomonitoring. It can greatly reduce the time spent on data processing for potential precursor ions. Additionally, the correlation of the retention time and logKow of the phthalate metabolites was explored, which provides a useful tool to reduce the number of identified candidates in the non-targeted screening.