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In this study, continuous in-source hydrogen/deuterium exchange (HDX) atmospheric pressure photoionization (APPI) mass spectrometry (MS) with continuous feeding of DO was developed and validated. DO was continuously fed using a capillary line placed on the center of a metal plate positioned between the UV lamp and nebulizer. The proposed system overcomes the limitations of previously reported APPI HDX-MS approaches where deuterated solvents were premixed with sample solutions before ionization. This is particularly important for APPI because solvent composition can greatly influence ionization efficiency as well as the solubility of analytes. The experimental parameters for APPI HDX-MS with continuous feeding of DO were optimized, and the optimized conditions were applied for the analysis of nitrogen-, oxygen-, and sulfur-containing compounds. The developed method was also applied for the analysis of the polar fraction of a petroleum sample. Thus, the data presented in this study clearly show that the proposed HDX approach can serve as an effective analytical tool for the structural analysis of complex mixtures. Graphical abstract ᅟ.

A solvent composition dependent signal reduction mechanism was suggested and evaluated for the (+)-APPI-MS analysis of polyaromatic hydrocarbons (PAHs) generating mainly molecular ions. Overall, the evidence provided in this work suggests that reactions between solvent cluster(s) and toluene molecular ions are responsible for the observed reductions in signal.

In this study, expanded polystyrene (EPS) was photodegraded in vitro, and its water-soluble degradation products were extracted using solid-phase extraction. An in vivo test using the MTT assay showed that EPS exhibited increased toxicity upon photodegradation. This clearly demonstrates the necessity of investigating the degradation products at a molecular level, and thus, we conducted analyses using high-resolution mass spectrometry coupled with liquid chromatography. Overall, 68 compounds were detected, of which 13 were identified after comparing the retention times and tandem mass spectra of the extracted compounds with those of standards. The toxicity of the degraded EPS was studied by examination of the detected compounds combined with published reports. In addition, the quantification of the most abundant compounds showed that discarded EPS can generate a significant amount of chemicals by UV degradation. The data in this study show that degraded EPS can pose a significant environmental threat as a source of potentially hazardous chemicals. This study provides a fundamental basis for the evaluation of the fate and toxicity of photodegraded EPS.

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