A method of Fourier transform near-infrared (FT-NIR) spectroscopy combined with partial least squares (PLS) model was successfully applied to investigate the hydrolysis kinetics of four kinds of silane coupling agents (phenyltriethoxysilane, vinyltriethoxysilane, 3-mercaptopropyltriethoxysilane, 3-chloropropyltriethoxysilane) in an acid-catalyzed EtOH system. The fast scanning speed and high sensitivity of the FT-NIR spectroscopy, and the powerful data processing ability of the PLS, enabled the method to quantitatively and accurately catch the fast changing H2O concentration during the hydrolysis processes without delay, realizing the study of the fast-paced hydrolysis reactions of the silane coupling agents. The results showed that electrophilic substitution occurred in the hydrolysis reactions, which followed second-order reactions and greatly depend on the catalyst concentration and reaction temperature. The hydrolysis rate constants, activation energy, and Arrhenius Frequency factors were gained. In conclusion, the FT-NIR PLS model is a powerful tool for hydrolysis kinetics researching of the silane coupling agents.
7 June 2021 in Food Additives & Contaminants: Part A
Sulphonamides (SAs) are widely used in animal husbandry. In our work, based on multi-walled carbon nanotubes, a novel residue method was developed for highly sensitive and determination trace levels of sulfamethoxazole, acetyl sulfamethoxazole and aditoprim in edible swine tissues by LC-MS/MS with magnetic solid-phase extraction. The samples were extracted using 2% ammoniated acetonitrile and purified by magnetic solid phase extraction (MSPE). Under the optimal conditions, good linearity was obtained ranging from 5 to 160 μg kg−1. The limits of detection (LOD) and quantification (LOQ) were 2 μg kg−1 and 5 μg kg−1 respectively. The average recoveries were 73.9–94.8% at different spiking levels. The inter-day RSDs were 6.2–10.7% and the intra-day RSDs were 2.4–5.4%. MSPE based on multi-walled carbon nanotubes was a simple and efficient method to enrich and separate the analyses and could be successfully applied for extraction of sulfamethoxazole, acetyl sulfamethoxazole and aditoprim residues in swine tissues.