New Method Based on Direct Analysis in Real-Time Coupled with Time-of-Flight Mass Spectrometry (DART-ToF-MS) for Investigation of the Miscibility of Polymer Blends

The miscibility of a series of binary blends such as polystyrene/poly(methyl methacrylate) (PS/PMMA), polystyrene/poly(vinyl chloride)(PS/PVC), poly(vinyl chloride)/poly(polymethyl methacrylate)(PVC/PMMA) and poly(ethylene-co-vinyl alcohol)/poly(lactide-co-glycolide acid) PEVAL/PLGA with equal ratios and poly(ethylene oxide)/poly(hydroxyl propyl methyl cellulose) (PEO/PHPMC) containing 30 and 70 wt% PEO, which were randomly chosen among the widely systems reported in the literature, was investigated by a new method based on a direct analysis in real-time coupled with time-of-flight mass spectrometry (DART-ToF-MS). To reach this goal these pairs of polymers and copolymers were prepared by solvent casting method. As a first step, the DSC technique was undertaken in this work to highlight the published results on the miscibility of these binary systems. The thermogravimetry analysis (TGA) was used to define the optimum decomposition temperature of these blends programmed for the study of miscibility using the DART-ToF-MS technique. The results obtained by this method based on the comparison of the nature of the fragments resulting from the isothermal decomposition of the blend with those of their pure components have been very effective in demonstrating the character of miscibility of these systems. Indeed, it was found that the PS/PMMA-50 and PS/PVC-50 blends were immiscible, PVC/PMMA-50 and PEVAL/PLGA-50 miscible, and the PEO/PHMC partially miscible. This method, which is rapid and uses a very small amount of sample (1–2 mg) can be extended in its application to other blends whose other methods used have shown their limits due to the intrinsic properties of the polymers involved

Development of In-Needle SPME Devices for Microextraction Applied to the Quantification of Pesticides in Agricultural Water

The chemical industry explosion in the 20th century has led to increased environmental pollution, affecting fauna, flora, and waterways. These substances alter water’s taste, color, and smell, making it unfit for consumption or toxic. Agricultural water networks face threats from pollution before and after treatment. Some chemical contaminants, like pesticides, are embedded in natural biogeochemical cycles. In this study, we developed a simple and low-cost procedure for the fabrication of needles coated with polydimethylsiloxane (PDMS) as an efficient sorbent for the microextraction of organic pollutant traces from water. The prepared needles were used as an alternative for commercial solid-phase micro-extraction (SPME) devices in analytical chemistry. The PDMS polymeric phase was characterized by Fourier-transform infrared spectroscopy (FT-IR), thermogravimetry (TGA), and scanning electron microscopy (SEM). The PDMS-coated needles were used for extraction of thirteen pesticides by direct-immersion solid-phase microextraction (DI-SPME) from contaminated waters, followed by determination with gas chromatography-mass spectrometry (GC-MS). The developed analytical method showed limits of detection (LODs) between 0.3 and 2.5 ng mL−1 and RSDs in the range of 0.8–12.2%. The homemade needles were applied for the extraction of pesticides in surface and ground aqueous samples collected from an agricultural area. Several target pesticides were identified and quantified in the investigated water samples

New Monomer Based on Eugenol Methacrylate, Synthesis, Polymerization and Copolymerization with Methyl Methacrylate–Characterization and Thermal Properties

Poly(eugenyl-2-hydroxypropyl methacrylate) (PEUGMA), poly(methyl methacrylate) (PMMA) and poly(eugenyl-2-hydroxypropyl methacrylate-co-methyl methacrylate) (PEUGMA-co-MMA) were synthesized by a free radical polymerization route in the presence of azobisisobutyronitrile. EUGMA was synthesized by etherification of the eugenol phenolic hydroxyl group with glycidyl methacrylate. Polymers and copolymers were characterized using size exclusion chromatography, Fourier transform infrared, and nuclear magnetic resonance. The effects of the encumbering substituent on the thermal behavior of the polymers and copolymers were studied by differential scanning calorimetry, thermogravimetry (TG) and direct analysis, using real-time, time-of-flight mass spectroscopy (DART-ToF-MS) methods. The results obtained revealed that for PEUGMA, the average molecular weight was 1.08 × 105, and increased slowly with the decrease in the EUGMA content in the copolymer. The order of the distribution of dyads comonomer units in the copolymer chains estimated by the Igarashi method based on the reactivity ratio does reveal a random distribution with a tendency toward alternation. The glass transition temperature of PEUGMA (46 °C) increased with the MMA content in the copolymer, and those of the copolymer fit well with the Johnston’s linearized expression. The TG analysis of pure PEUGMA revealed a significantly high thermal stability compared to that of PMMA. During its degradation, the preliminary decomposition was at 340 °C, and decreased as the MMA units increased in the copolymer. The DART-ToF-MS analysis revealed that the isothermal decomposition of PEUGMA led to a regeneration of raw materials such as EUGMA, GMA and EUG, in which the maximum amount was achieved at 450 °C

An uncommon liver abscess secondary to an ingested foreign body: A case report

Introduction: This article discusses a case study involving a unique occurrence of a hepatic abscess caused by the presence of an ingested foreign body. Hepatic abscesses, characterized by pus accumulation within liver tissue, often result from various infections, with some cases having unidentified origins. Case presentation: This study focuses on a 75-year-old man who presented at an emergency department with persistent pain in the right upper abdomen and fever for ten days. Diagnostic tests revealed a low-density, multiloculated mass in the liver and a hyperdense linear structure near the duodenum, indicating a hepatic abscess originating from duodenal perforation due to a foreign body that had migrated from ingestion. The patient underwent antibiotic treatment and a surgical procedure involving laparotomy to extract the foreign object and drain the abscess. Conclusion: this case study underscores the rare occurrence of hepatic abscesses caused by ingested foreign bodies. Swift and accurate diagnosis, along with appropriate treatment involving foreign body removal and abscess drainage, are pivotal for favorable patient outcomes. The choice of treatment strategy impacts hospital stay duration, and understanding potential complications from foreign body ingestion enhances patient management and care

New Method Based on the Direct Analysis in Real Time Coupled with Time-of-Flight Mass Spectrometry to Investigate the Thermal Depolymerization of Poly(methyl methacrylate)

In this work, the isothermal decomposition of poly(methyl methacrylate) synthesized in bulk by the radical route of methyl methacrylate in the presence of azobisisobutyronitrile as the initiator was carried out and monitored for the first time with the DART-Tof-MS technique at different temperatures. Nuclear magnetic resonance (NMR) analysis revealed a predominantly atactic microstructure, and size-exclusion chromatography (SEC) analysis indicated a number average molecular weight of 3 × 105 g·mol−1 and a polydispersity index of 2.47 for this polymer. Non-isothermal decomposition of this polymer carried out with thermogravimetry analysis (TGA) showed that the weight loss process occurs in two steps. The first one starts at approximately 224 °C and the second at 320 °C. The isothermal decomposition of this polymer carried out and monitored with the DART-Tof-MS method revealed only one stage of weight loss in this process, which begins at approximately 250 °C, not far from that of the second step observed in the case of the non-isothermal process conducted with the TGA method. The results obtained with the MS part of this technique revealed that the isothermal decomposition of this polymer regenerates a significant part of methyl methacrylate monomer, which increases with temperature. This process involves radical chain reactions leading to homolytic chain scissions and leading to the formation of secondary and tertiary alkyl radicals, mainly regenerating methyl methacrylate monomer through an unzipping rearrangement. Although they are in the minority, other fragments, such as the isomers of 2-methyl carboxyl, 4-methyl, penta-2,4-diene and dimethyl carbate, are also among the products detected. At 200 °C, no trace of monomer was observed, which coincides with the first step of the weight loss observed in the TGA. These compounds are different to those reported by other researchers using TGA coupled with mass spectrometry in which methyl isobutyrate, traces of methyl pyruvate and 2,3-butanonedione were detected