Efficiencies of Acid and Base-Catalyzed Methylation of Vegetable Oils by Ambient Mass Spectrometry

The fatty acids (FA) profile is an important parameter for quality control and typification for foods in general. These profiles work as a sort of "fingerprint", and may be useful to monitor frauds and deterioration of diverse types of foods. For vegetable oils, the FA profile is commonly determined after hydrolysis, methylation and gas chromatography (GC) analysis. In this work, the acid and base-catalyzed soybean oil methylation methods was monitored via GC-FID and also by ambient sonic-spray ionization mass spectrometry (EASI-MS). The base-catalyzed method is much superior regarding other esterification assays, because it is cheaper, less toxic, no oxidation products are formed and its reaction yield is greater (95.66% m/m against 92.86% and 94.51% from acid-catalyzed methylation methods, respectively)

Antimicrobial Composites Based on Methacrylic Acid–Methyl Methacrylate Electrospun Fibers Stabilized with Copper(II)

This study presents fibers based on methacrylic acid–methyl methacrylate (Eudragit L100) as Cu(II) adsorbents, resulting in antimicrobial complexes. Eudragit L100, an anionic copolymer synthesized by radical polymerization, was electrospun in dimethylformamide (DMF) and ethanol (EtOH). The electrospinning process was optimized through a 22-factorial design, with independent variables (copolymer concentration and EtOH/DMF volume ratio) and three repetitions at the central point. The smallest average fiber diameter (259 ± 53 nm) was obtained at 14% w/v Eudragit L100 and 80/20 EtOH/DMF volume ratio. The fibers were characterized using scanning electron microscopy (SEM), infrared spectroscopy in attenuated total reflectance mode (FTIR-ATR), and differential scanning calorimetry (DSC). The pseudo-second-order mechanism explained the kinetic adsorption toward Cu(II). The fibers exhibited a maximum adsorption capacity (qe) of 43.70 mg/g. The DSC analysis confirmed the Cu(II) absorption, indicating complexation between metallic ions and copolymer networks. The complexed fibers showed a lower degree of swelling than the non-complexed fibers. The complexed fibers exhibited bacteriostatic activity against Gram-negative (Pseudomonas aeruginosa) and Gram-positive (Staphylococcus aureus) bacteria. This study successfully optimized the electrospinning process to produce thin fibers based on Eudragit L100 for potential applications as adsorbents for Cu(II) ions in aqueous media and for controlling bacterial growth