Currently, there is a growing interest in the study of environmental degradation pathways of organic contaminants such as pesticides, with the objective to better understand their potential risk for environmental systems and living organisms. In this context, DFT (conceptual density functional theory) and predictive methods may systematically be used to simplify and accelerate the elucidation of environmental degradation. We report herein the electrochemical behavior/degradation of the carbendazim (CBZ) fungicide widely used to treat cereal and fruit crops. https://www.selleckchem.com/products/guanosine.html Oxidative degradation of CBZ was studied using an electrochemical flow-through cell directly coupled to a mass spectrometer for rapid identification of CBZ degradation products. The structural elucidation of CBZ oxidation products was based on retention time, accurate mass, isotopic distribution and fragmentation pattern by using LC-HRMS an LC-HRMS2. The most important chemical reactions found to occur in the transformation of CBZ were hydrolysis and hydroxylation. EC-LC-MS and EC-MS analysis has made it possible to highlight the identification of degradation products of CBZ. In addition to previously known transformation products common to those observed during environmental degradation (monocarbomethoxyguanidine, benzimidazole-isocyanate, 2-aminobenzimidazole, hydroxy-2-aminobenzimidazole, hydroxycarbendazim, CBZ-CBZ dimer), two new degradation products were identified in this work a quinone imine and a nitrenium ion. Electrochemistry mass spectrometry hyphenated techniques represent an accessible, rapid and reliable tool to elucidate the oxidative degradation of CBZ, including reactive degradation products and conjugates.As a main contaminant in fish, microcystin-LR (MC-LR) leads to serious liver problems; therefore, the development of MC-LR sensors is important to guarantee aquatic food safety. In this work, a near-infrared (NIR) light-excited photoelectrochemical (PEC) immunosensor was developed through conjugation of Ag2S cubes with Au nanoparticles (NPs) to determine MC-LR residues in fish. Specifically, as a narrow-band semiconducting material, Ag2S is capable of absorbing NIR light. Taking advantage of the localized surface plasmon resonance (LSPR) effect along with good conductivity of AuNPs, the developed AuNP/Ag2S/fluorine-doped tin oxide (FTO) owns much higher photoelectric conversion efficiency, and the photocurrent is 5.3 times that of Ag2S FTO. Subsequently, the NIR-driven AuNP/Ag2S/FTO was used to immobilize antibodies (Abs) for MC-LR. Their specificity to MC-LR led to steric effects and limited surface electron transfer, causing reduce of the photocurrent. Through AuNP/Ag2S-composite amplification and immunological specificity, the PEC immunosensor can quantitatively measure MC-LR with a wide linear range, 10 pg L-1 to 10 μg L-1, and a much low detection limit, 7 pg L-1 (S/N = 3). Finally, the NIR PEC sensor was employed in the analysis of MC-LR contents in fish. This work reveals the NIR-responsive ability of Ag2S cubes and deepens understanding the role of AuNPs in the PEC process. Due to the superior properties, the developed NIR PEC immunosensor has been demonstrated as a promising method for analysis of biological samples.A high-efficiency enrichment method is required for determination of trace-level volatile terpenes in fish tissue, since the presence of such compounds in fish at elevated levels may induce bad sensory acceptance of fish meat, thus degrading its customer acceptance and consequently, its market value. In this study, a solid-phase microextraction (SPME) arrow configuration using a thick sorbent coating (120 μm, PDMS/CWR) was applied to enrich selected terpenes, namely α-pinene, limonene, linalool, and citronellol, in fish tissue (Oreochromis niloticus). Due to the thicker coating of the SPME arrow, a longer extraction time of 60 min was required to reach equilibrium extraction in comparison to the traditional fiber configuration. SPME conditions such as extraction temperature (60 °C), desorption temperature (250 °C), and salt effect (10% NaCl) were optimized for the developed application using the arrow configuration. The developed method exhibited good linearity at a concentration range of 5.0-500.0 μg L-1 for α-pinene and limonene, and 50.0-500.0 μg L-1 for linalool and citronellol. In addition, the coefficients of determination (R2) for all terpenes ranged from 0.9990 to 0.9999. The developed method was shown to be robust with good inter-day reproducibility in the range of 3.6-8.3%. Method sensitivity was assessed in terms of limits of detection (LODs) and limits of quantification (LOQs), with higher sensitivity achieved for α-pinene and limonene (LODs of 1.7 μg L-1) in comparison to linalool (LOD, 5.0 μg L-1) and citronellol (LOD, 17.0 μg L-1). Theoretical calculations verified that the increased coating thickness afforded by the arrow configuration can enable higher method sensitivity and widen the range of detected compounds for the headspace SPME.In this research, 9-methylacridine and 9-undecylacridine were synthesized through Bernthsen's reaction and well characterized using gas chromatography-mass spectrometry (GC-MS) and nuclear magnetic resonance (NMR). Two mixed-mode stationary phases were developed by functionalizing silica with 9-methylacridine and 9-undecylacridine. Then, two modified silicas were characterized by elemental analysis, thermogravimetric analysis (TGA), and fourier transform-infrared spectroscopy (FT-IR). Due to the extent of conjugative rings, the hydrophobic hydrocarbon chain, and anion exchange sites of 9-methylacridinium and 9-undecylacridinium group on the silica gel of columns, mixed-mode stationary phases were designed with multiple interactions including π-π stacking interaction, reverse phase, hydrophilic interaction, and anion exchange. According to the type of acridine, different interactions may be formed in the target column. Polycyclic aromatic hydrocarbons (PAHs), alkylbenzenes, pyridines and parabens were chromatographed on π-π stacking modes and RPLC, where anion exchange sites can be applied for the separation of inorganic anions on AEC mode. Considering the structure of the stationary phases, these columns were used to separate organic compounds with higher polarity on the HILIC retention. The performance of the columns was investigated by the chromatographic parameters in terms of column efficiency (N/m), asymmetry factor (Af), retention factor (k), and resolution (Rs). The mixed-mode stationary phases can be successfully employed to conduct chromatographic separation on a wide range of samples with a single column.