Regulation of the concentration of toxic substances derived from tobacco products is carried out to reduce the incidence of deaths and diseases caused by the use of tobacco cigarettes, as well as to decrease attractiveness, addiction, and toxicity. In this context, modified risk tobacco products (MRTPs) have been developed to provide alternative products that have the potential to reduce the risk and harm to the population when compared to smoking conventional cigarettes. One example of an MRTP is the Tobacco Heating System (THS2.2), which, unlike conventional cigarettes, heats the tobacco instead of burning it, producing a significantly reduced amount of harmful and potentially harmful constituents (HPHCs). To review the data on the content of HPHCs in the aerosols and smoke of conventional cigarettes and those of the THS2.2 type, a critical review of scientific publications in this field was conducted from January 2015 to May 2022. The selection of scientific publications from open sources was carried out from the Scopus, Web of Science, Google Scholar, PubMed, MedLine databases, and others. A similar analysis was carried out on the information already available on the websites of Philip Morris International (PMI), Elsevier, Springer, and other relevant web resources that include information on the use of the THS2.2. After conducting a comprehensive analysis of results from both independent and industry-sponsored studies, it was noted that HPHCs are not completely eliminated from the aerosol produced by heated tobacco products (HTPs). However, the levels of these HPHCs from the PMI List of 58 Constituents (PMI-58 list) are consistently lower and significantly reduced when compared to the mainstream smoke emitted by conventional cigarettes. This suggests that while HTPs present reduced emissions of toxicants in comparison, they are not completely free from risks.
Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous environmental pollutants composed of two or more fused aromatic rings, which are characterized by low water solubility, low vapor pressure, and high melting and boiling points, depending on their structures. Due to the lipophilic nature of these compounds, they are strongly adsorbed by soil and sediments. The United States Environmental Protection Agency (USEPA) has declared 16 PAHs as priority pollutants in 1983 based on their existence of highest concentrations, greater exposure and toxicity. The purpose of this article is to validate a method for determining ten PAHs in soil by ultra-high pressure liquid chromatography with UV-VIS detection. The evaluated performance parameters are: selectivity, linearity, accuracy, precision, limit of detection (LOD), limit of quantification (LOQ), limit of repeatability (r), recovery (R) and uncertainty of measurement (U). LOD ranged between 0.02 mg/mL and 0.3 mg/mL, LOQ ranged between 0.2 mg/mL and 0.95 mg/mL. The recovery values ranged between 75.4% for benzo(b) fluoranthen and 89.8% for chrysene. These values were established using a soil reference material which was extracted with hexane/acetone using a Soxhlet method. The PAH compounds were separated using a nonpolar stationary phase column and were determined by liquid chromatography with Array Diode Detector at 254 nm.
Formalin is used as a preservative in fish, as fish is a perishable product. The present study describes the development of a battery-operated portable colorimeter for the on-site determination of formalin in fish. Combining light sources of various wavelengths with an electric circuit and light dependent resistor results in a simple and cost-effective colorimeter. The gadget functions based on the light received by the light-dependent resistor, which is directly linked to the circuit board for resistance measurement using the resistance to absorbance connection and, the resistance values were converted to absorbance. The developed portable colorimeter is calibrated for the quantitative detection of formalin. The device exhibited an efficient detection of formalin at the range of 1 to 20 ppm. The portable colorimeter exhibited high accuracy and the results are promising for on-site detection of formalin in fish.
The purpose of this paper is elucidating the stereochemistry of a complex obtained by coordinating to divalent nickel a naphthalene-1,4-dione based chemical compound, namely N-(3-mercapto-naphthalene-1,4-dione-2-yl)nicotinamide. As this particular transition metal ion may lead to different coordination geometries and also tacking into account the fact that the organic ligand contains six heteroatoms, it seem to be worth clarifying denticity of the ligand, the coordination geometry (including stereoisomerism) and, of course, what are the atoms involved into the coordination process. The study has been conducted by computational means, followed by quantum-chemical calculations and comparative interpretation of the UV-Vis spectra of both the ligand and the complex compound, in order to find out in which case the structural assessment is consistent with the electronic transitions exhibited whithin the spectra, i.e. which of the several theoretical coordination posibilities is the actual one. This investigation leads to the conclusion that the organic compound acts as a bidentate ligand and, moreover, the complex compound has a square-planar coordination geometry, the two heteroatoms through which the coordination is realized being the sulfur atom and the nitrogen atom directly bonded to the naphthalene-1,4-dione heterocycle. This is an important achievement, as the properties of the complex compound � including its biologic activity - are obviously related to the coordination manner.
This article aimed to separate and identify molecular species obtained in the sol-gel process by gas chromatography coupled with mass spectrometry (GC-MS), for the reaction mixture with methyltrimethoxysilane (MTMOS). In the presence of an unhydrolyzed methyl group, the molecular species starting with the cyclic trimers, a series of geometric isomers were separated and identified due to the position of the methyl groups in relation to the ring plane of each siloxane molecule; in addition, for the hydrolyzed products, isomers with different relative positions of the hydroxyl groups to the methyl and methoxy groups were separated and identified. The reactivity of the new molecular species formed determines subsequent stages of the sol-gel process.
