Strong reducing agents like lithium aluminum hydride (LiAlH4, LAH) are frequently employed by industry and academic laboratories in syntheses and other research applications. Due to LAH’s reactivity, several laboratory explosions and fires have been documented in the literature and on various EH&S webpages at universities. Some of the accidents were caused by incorrect handling of LAH or by improper chemical processes, such as weighing on regular paper, grinding, and creating friction, using contaminated solvents and glassware, and physically scraping the material during transfers. In many of these cases, researchers did not have access to a guidance document or an SOP for many of these incidents, and no thorough risk assessment was carried out. Academic laboratories can avoid similar accidents and associated property damage by developing a safety guidance document that identifies every facet of LAH manipulation in the experiment, including reaction setup, procedures for weighing and transferring material to the reaction vessel, heating, and cooling during the reaction, quenching the reaction, and waste disposal. This LAH guidance document can be used to produce a manipulation-specific SOP that covers best practices and precautions for a variety of substrates and reaction scales.

ACS Chem. Health Saf. 2024, XXXX, XXX, XXX-XXX (10.1021/acs.chas.3c00102)

PDF

Several food contact materials (FCMs) contain non-intentionally added substances (NIAS), and most of the substances that migrate from plastic food packaging are unknown. This review aimed to situate the main challenges involving unknown NIAS in plastic food packaging in terms of identification, migration tests, prediction, sample preparation, determination methods and risk assessment trials. Most studies have identified NIAS in plastic materials as polyurethane adhesives (PU), polyethylene terephthalate (PET), polyester coatings, polypropylene materials (PP), multilayers materials, plastic films, polyvinyl chloride (PVC), recycled materials, high-density polyethylene (HDPE) and low-density polyethylene (LDPE). Degradation products are almost the primary source of NIAS in plastic FCMs, most from antioxidants as Irganox 1010 and Irgafos 168, following by oligomers and side reaction products. The NIAS assessment in plastics FCMs is usually made by migration tests under worst-case conditions using food simulants. For predicted NIAS, targeted analytical methods are applied using GC-MS based methods for volatile NIAS and GC-MS and LC-MS based methods for semi- and non-volatile NIAS; non-targeted methods to analyze unknown NIAS in plastic FCMs are applied using GC and LC techniques combined with QTOF mass spectrometry (HRMS). In terms of NIAS risk assessment and prioritization, the threshold of toxicological concern (TTC) concept is the most applied tool for risk assessment. Bioassays with sensitive analytical techniques seem to be an efficient method to identify NIAS and their hazard to human exposure; the combination of genotoxicity testing with analytical chemistry could allow the Cramer class III TTC application to prioritize unknown NIAS. The scientific justification for implementing a molecular weight-based cut-off (<1000 Da) in the risk assessment of FCMs should be reevaluated. Although official guides and opinions are being issued on the subject, the whole chain’s alignment is needed, and more specific legislation on the steps to follow to get along with NIAS.

Polymers 2021, 13(13), 2077 (10.3390/polym13132077)

PDF

This tutorial provides the theoretical background, the principles, and applications of Electrochemical Impedance Spectroscopy (EIS) in various research and technological sectors. The text has been organized in 17 sections starting with basic knowledge on sinusoidal signals, complex numbers, phasor notation, and transfer functions, continuing with the definition of impedance in electrical circuits, the principles of EIS, the validation of the experimental data, their simulation to equivalent electrical circuits, and ending with practical considerations and selected examples on the utility of EIS to corrosion, energy related applications, and biosensing. A user interactive excel file showing the Nyquist and Bode plots of some model circuits is provided in the Supporting Information. This tutorial aspires to provide the essential background to graduate students working on EIS, as well as to endow the knowledge of senior researchers on various fields where EIS is involved. We also believe that the content of this tutorial will be a useful educational tool for EIS instructors.

ACS Meas. Sci. Au 2023, 3, 3, 162–193 (10.1021/acsmeasuresciau.2c00070)

PDF