Search

This article provides an overview of the status of analytical chemistry education worldwide. The International Union of Pure and Applied Chemistry (IUPAC) has funded a project to assess the state of analytical chemistry education due to concerns about its declining professional status. The article discusses the challenges of conducting a survey on this topic due to the different terminologies and curricular systems used globally. It also examines how analytical chemistry is incorporated into the curricula of several countries, including Australia, Germany, Peru, South Africa, the United Kingdom, and the United States. The educational systems vary in terms of structure, requirements, and hours dedicated to analytical chemistry. The article emphasizes the importance of employers considering the diverse skills and backgrounds of graduates in this field. [Extracted from the article]

In the last two decades, environmental experts have focused on the development of several biological, chemical, physical, and thermal methods/technologies for remediation of PAH‐polluted water. Some of the findings have been applied to field‐scale treatment, while others have remained as prototypes and semi‐pilot studies. Existing treatment options include extraction, chemical oxidation, bioremediation, photocatalytic degradation, and adsorption (employing adsorbents such as biomass derivatives, geosorbents, zeolites, mesoporous silica, polymers, nanocomposites, and graphene‐based materials). Electrokinetic remediation, advanced phytoremediation, green nanoremediation, enhanced remediation using biocatalysts, and integrated approaches are still at the developmental stage and hold great potential. Water is an essential component of the ecosystem and highly susceptible to PAH contamination due to crude oil exploration and spillage, and improper municipal and industrial waste management, yet comprehensive reviews on PAH remediation are only available for contaminated soils, despite the several treatment methods developed for the remediation of PAH‐polluted water. This review seeks to provide a comprehensive overview of existing and emerging methods/technologies, in order to bridge information gaps toward ensuring a green and sustainable remedial approach for PAH‐contaminated aqueous systems. Practitioner points: Comprehensive review of existing and emerging technologies for remediation of PAH‐polluted water.Factors influencing efficiency of various methods, challenges and merits were discussed.Green nano‐adsorbents, nano‐oxidants and bio/phytoremediation are desirous for ecofriendly and economical PAH remediation.Adoption of an integrated approach for the efficient and sustainable remediation of PAH‐contaminated water is recommended. [ABSTRACT FROM AUTHOR]

Unbanded crocodilian eggs do not form an opaque band around their lesser circumference, indicating fertilization failure or early embryonic death. Assuming they represent fertile eggs prior to the onset of embryonic metabolism, the concentration and content of calcium (Ca) and phosphorus (P) in each component (shell, shell membrane, yolk and albumen) of unbanded farm‐laid Nile crocodile (Crocodylus niloticus) eggs were described. The grouping effect of clutch (clutch effect) on each component's Ca and P concentration and content were assessed. Using regression models, the clutch size, clutch laying date, pond of origin, component mass and component Ca and P concentration were evaluated for an effect on each component's Ca and P content. Eggshell made by far the greatest contribution to total egg Ca whilst contributing no measurable P. Yolk contributed by far the greatest quantity of P and a significant quantity of Ca. Albumen contributed variable, but generally very low quantities of Ca and P to the egg. A strong clutch effect existed for shell Ca content and yolk Ca and P concentration and content. A very weak clutch effect existed for shell Ca concentration, and albumen Ca and P concentration. Shell membrane was an unreliable sample type in this study, likely reflecting issues with processing. Shell Ca and yolk Ca and P content were influenced primarily by component mass, and secondarily by element concentration. Albumen Ca and P content was principally influenced by element concentration. These descriptive findings will guide sample selection for future research. [ABSTRACT FROM AUTHOR]

Students often regard laboratory instruments as 'black boxes' which generate results, without understanding their principles of operation. This lack of understanding is a concern because the correct interpretation of analytical results and the limitations thereof is invariably based on an understanding of the mechanism of measurement. Moreover, a number of tertiary institutions in Africa have very limited resources and access to laboratory equipment, including that related to the field of photonics, which prevents students from acquiring hands-on practical experience. We address both of these challenges by describing how students can assemble a novel, low-cost spectrophotometer, called the SpecUP, which can then be used in a range of experiments. The same kind of information can be generated as that obtained with costly commercial spectrophotometers (albeit of a lower quality). With the SpecUP, students also have the opportunity to vary instrumental parameters and to observe the effects these changes have on their experimental results, allowing for enquiry-based learning of spectroscopic principles. The results obtained for some chemistry-related spectrophotometric experiments are described for each of the two operational modes of the SpecUP, although the instrument can be applied in fields ranging from physics to biochemistry. [ABSTRACT FROM AUTHOR]

Here we functionalized micro-scaled polymer beads with nano-scaled quantum dots and demonstrate optical trapping and tweezing, with in-situ fluorescence measurement, in an all-digital all-optical configuration. We outline the chemistry required to facilitate this, from deactivating the optical trapping environment to size, adhesion and agglomeration control. We introduce a novel holographic optical trapping set-up that leverages on vectorially structured light, allowing for the delivery of tuneable forms of light from purely scalar to purely vector, including propagation invariant flat-top beams for uniform illumination and tailored intensity gradient landscapes. Finally, we show how this has the potential to quench bleaching in a single wavelength trap by linear (spatial mode) rather than non-linear effects, advancing the nascent field of optics for chemistry. [ABSTRACT FROM AUTHOR]

Here we functionalized micro-scaled polymer beads with nano-scaled quantum dots and demonstrate optical trapping and tweezing, with in-situ fluorescence measurement, in an all-digital all-optical configuration. We outline the chemistry required to facilitate this, from deactivating the optical trapping environment to size, adhesion and agglomeration control. We introduce a novel holographic optical trapping set-up that leverages on vectorially structured light, allowing for the delivery of tuneable forms of light from purely scalar to purely vector, including propagation invariant flat-top beams for uniform illumination and tailored intensity gradient landscapes. Finally, we show how this has the potential to quench bleaching in a single wavelength trap by linear (spatial mode) rather than non-linear effects, advancing the nascent field of optics for chemistry. [ABSTRACT FROM AUTHOR]

Biomass burning is a significant anthropogenic source of air pollution, including the preharvest burning of sugar cane. These burn events result in atmospheric emissions, including semivolatile organic compounds, that may have adverse impacts on air quality and human health on a local, regional, and even a global scale. Gaseous and particulate polycyclic aromatic hydrocarbon (PAH) emissions from various sugar cane burn events in the province of Kwa‐Zulu Natal in South Africa were simultaneously sampled using a portable denuder sampling technology, consisting of a quartz fiber filter sandwiched between two polydimethylsiloxane multichannel traps. Total gas and particle phase PAH concentrations ranged from 0.05 to 9.85 µg m–3 per individual burn event, and nine PAHs were quantified. Over 85% of all PAHs were found to exist in the gas phase, with smaller two‐ and three‐ring PAHs, primarily naphthalene, 1‐methyl naphthalene, and acenaphthylene, being the most dominant and causing the majority of variance between the burn sites. The PAH profiles differed between the different burn events at different sites, emphasizing the significant influence that the crop variety, prevailing weather conditions, and geographical location has on the type and number of pollutants emitted. The potential carcinogenicity of the PAH exposure was estimated based on toxic equivalency factors that showed varying risk potentials per burn event, with the highest value of 5.97 ng m–3. Environ Toxicol Chem 2023;42:778–792. © 2023 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC. [ABSTRACT FROM AUTHOR]

Semi-volatile organic compounds (SVOCs), partitioned between particulates and vapours of an aerosol, require special attention. The toxicological effects caused by the inhalation of such aerosols may depend on the concentration and in which phase the organic compounds are found. A personal denuder-gas–particle separation aerosol sampler was developed to provide information about the partitioning of aerosols from organic compounds. The sampler was tested in a series of controlled laboratory experiments, which confirmed the capability and accuracy of the sampler to measure gas–particle mixtures. An average difference of 14.8 ± 4.8% was found between sampler and reference laboratory instruments. The obtained results showed that our sampler enables a more accurate measurement of the SVOC aerosols' gas–particle fractionation, compared with that of conventional samplers. [ABSTRACT FROM AUTHOR]

We present experimental results of emission factors from a suite of domestic coal-burning braziers (lab fabricated and field collected) that span the possible range of real-world uses in the Highveld region of South Africa. The conventional bottom-lit updraft (BLUD) method and the top-lit updraft (TLUD) method were evaluated using coal particle sizes between 20 mm and 40 mm. Emission factors of CO2, CO and NOx were in the range of 98-102 g/MJ, 4.1-6.4 g/MJ and 75-195 mg/MJ, respectively. Particulate matter (PM2.5 and PM10) emissions were in the range 1.3-3.3 g/MJ for the BLUD method and 0.2-0.7 g/MJ for the TLUD method, for both field and lab-designed stoves. When employing the TLUD method, emission factors of PM2.5/PM10 reduced by up to 80% compared with those when using the BLUD method. Results showed the influence of ventilation rates on emission factors, which reduced by ~50% from low to high ventilation rates. For energy-specific emission rates, the combined (3-h) PM10 emission rates were in the range of 0.0028-0.0120 g/s, while the combined average CO emission rates were in the range of 0.20-0.26 g/s, with CO2 emission rates in the range of 0.54-0.64 g/s. The reported emission factors from coal braziers provide the first comprehensive, systematic set of emission factors for this source category, and fill a major gap in previous efforts to conduct dispersion modelling of South African Highveld air quality. [ABSTRACT FROM AUTHOR]

Despite extensive electrification of low-income residential areas on the South African Highveld, extensive use is still made of wood and coal as domestic fuels, particularly for winter space heating. In informal settlements characterised by poverty and lacking electrification, coal is combusted in non-standardised, inefficient and polluting metal braziers, colloquially known as imbaulas. Copious emissions from domestic coal fires result in elevated household and ambient air pollution levels well above national air quality limits. Despite the severity of this pollution as a public health issue, emissions data from residential coal-burning braziers are still scarce. Consequently, there is a need to evaluate the emission characteristics of these devices. In this paper, we report on controlled combustion experiments carried out to investigate systematically influences of fire-ignition methods and stove ventilation rates on gaseous and condensed matter (smoke) emissions from informal residential coal combustion braziers. Two methods of stove ignition--conventional bottom-lit updraft (BLUD) and the top-lit updraft (TLUD) (colloquially known as the Basa njengo Magogo) were investigated. Emission factors (EFs) were found to be dependent on fire ignition method and stove ventilation rates. The top-lit ignition method reduces PM10/PM2.5 by 76% to 80% compared to the BLUD method. Carbon monoxide emissions do not change significantly with the ignition method. Pollutant emissions from normal combustion in high ventilation conditions were low compared to pollutants emitted when an oxygen deficient atmosphere was created under low ventilation conditions. High stove ventilation rates resulted in a 50% reduction in PM10/PM2.5 emissions compared to the low ventilation rates. Emissions of gaseous and particulate matter from incomplete combustion can be minimised by design optimisation of the braziers. Ideally, the emissions of condensed matter particles (which form the bulk of emitted particles in residential coal fires) can be reduced through good mixing of emitted gases and air, and by ensuring a long residence time in the high temperature oxygen rich post combustion zone, to allow for complete oxidation. This study is significant in that it presents the first systematic and comprehensive study of factors affecting emissions from coal braziers. [ABSTRACT FROM AUTHOR]

Multi-channel polydimethylsiloxane rubber traps were used to sample the headspace of rosemary samples (two essential oils from different sources, one oleoresin and one dried herb) followed by comprehensive two-dimensional gas chromatography - time of flight mass spectrometry (GCxGC-TOFMS) orGC-MS analyses.The aroma of different headspace samples was characterized using a custom-built olfactory apparatus. The differences between the aroma profileswere evident from bubble plots of the perceived aroma at different temperatures. The samples were heat-treated to simulate cooking of food products, and were then reassessed to determine any changes in the aroma profile. It was found that the intense menthol and cooling aromas subsided in all the samples with heating. GCxGC-TOFMS allowed for separation of the numerous components in the headspace samples. Many terpenes and aliphatics were thus tentatively identified and the relative peak areas were compared to better understand the mixture that contributes to the rosemary aroma. [ABSTRACT FROM AUTHOR]