Screening of xenobiotics by ultra-performance liquid chromatography-mass spectrometry using in-source fragmentation at increasing cone voltages: library constitution and an evaluation of spectral stability

In clinical and forensic toxicology, general unknown screening is used to detect and identify exogenous compounds. In this study, we aimed to develop a fast (15 min) comprehensive screening method for 500 toxicologically relevant analytes based on ultra-performance liquid chromatography (UPLC) coupled with a quadrupole mass spectrometer (MS) system operated in full scan mode. Data were acquired using both positive and negative electrospray ionization by scanning across the range m/z 80-650. For each ionization mode, data were also collected under multiple fragmentation conditions (i.e., at six different cone voltages). Consequently, each molecule could be characterized by a combination of retention time and up to a maximum of 12 individual spectra. Investigation of the 500 analytes resulted in the compilation of a library containing 2975 spectra. An assessment of the stability of these spectra was evaluated under various conditions, that is, the impact of increasing drug concentration and the presence of biological matrix. In addition, the transferability of the spectral library was assessed by comparison with data acquired using several other instruments of same model and from the same manufacturer. These data are presented in addition to the utility of the method for the analysis of routine clinical and forensic samples. Following extraction, identified compounds were compared to those found with two other techniques, one based on immunoassay and the other, on high-performance liquid chromatography-photodiode-array.