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In the search of new robust and environmental-friendly analytical methods able to answer quantitative issues in pharmacology, we explore liquid chromatography (LC) associated with elemental mass spectrometry (ICP-MS) to monitor peptides in such complex biological matrices. The novelty is to use mass spectrometry to replace radiolabelling and radioactivity measurements, which represent up-to now the gold standard to measure organic compound concentrations in life science. As a proof of concept, we choose the vasopressin (AVP)/V1A receptor system for model pharmacological assays. The capacity of ICP-MS to provide highly sensitive quantitation of metallic and hetero elements, whatever the sample medium, prompted us to investigate this technique in combination with appropriate labelling of the peptide of interest. Selenium, that is scarcely present in biological media, was selected as a good compromise between ICP-MS response, covalent tagging ability using conventional sulfur chemistry and peptide detection specificity. Applying selenium monitoring by elemental mass spectrometry in pharmacology is challenging due to the very high salt content and organic material complexity of the samples that produces polyatomic aggregates and thus potentially mass interferences with selenium detection. Hyphenation with a chromatographic separation was found compulsory. Noteworthy, we aimed to develop a straightforward quantitative protocol that can be performed in any laboratory equipped with a standard macrobore LC-ICP-MS system, in order to avoid time-consuming sample treatment or special implementation of instrumental set-up, while allowing efficient suppression of all mass interferences to reach the targeted sensitivity. Significantly, a quantification limit of 57 ng Se L-1 (72 femtomoles of injected Se) was achieved, the samples issued from the pharmacological assays being directly introduced into the LC-ICP-MS system. The established method was successfully validated and applied to the measurement of the vasopressin ligand affinity for its V1A receptor through the determination of the dissociation constant (Kd) which was compared to the one recorded with conventional radioactivity assays.

The extensive and unregulated use of antibacterial drugs in animal farms in Lebanon can lead to detrimental consequences for the public health. To monitor the levels of sulfonamides and their metabolites in farms in Lebanon, a total of 304 meat samples were collected and analyzed using liquid chromatography coupled to triple quadrupole and hybrid linear ion trap-Orbitrap mass spectrometry following QuEChERS-based extraction. Sulfonamide residues could be detected in forty-six samples, ten of which contained a concentration of sulfaquinoxaline (151.4–1196.7 μg kg −1 in chicken samples) and sulfadiazine (109.8 μg kg −1 in a beef sample) exceeding the European Union-based maximum residue level by 1–12 folds, and thus were unfit for human consumption. Several acetylated, hydroxylated, and/or sulfated metabolites were identified, some of which were not previously detected in edible tissues. Most identified metabolites exhibited potential toxicity equivalent or higher than that of the parent molecule as estimated by in silico tests. [ABSTRACT FROM AUTHOR]