Analytica, Volume 3, Issue 3 (September 2022) – 7 articles

Accurate DNA quantification is a highly important method within molecular biology. Methods widely used to quantify DNA are UV spectrometry and fluorometry. In this research, seven different DNA samples and one blank (MilliQ ultrapure water) were quantified by three analysts using one spectrophotometric (i.e., a NanoDrop instrument) and three fluorometric (i.e., the AccuGreen High Sensitivity kit, the AccuClear Ultra High Sensitivity kit, and the Qubit dsDNA HS Assay kit) methods. An analysis of variance (ANOVA) scheme was used to determine the influence of the analyst, the method, and the combination of analyst and method, on DNA quantification. For most samples, the measured DNA concentration was close to or slightly above the concentration of 10 ng/$\mathsf{\mu }$L as specified by the supplier. Results obtained by the three analysts were equal. However, it was found that, compared to the fluorometric kits, the used spectrophotometric instrument in the case of fish DNA samples tends to overestimate the DNA concentration. Therefore, if sufficient sample volume is available, a combination of a spectrophotometric and a fluorometric method is recommended for obtaining data on the purity and the dsDNA concentration of a sample. Full article

The geometrical and topological features of metal-organic frameworks (MOFs) play an important role in determining their ability to capture and store methane (CH₄). Methane is a greenhouse gas that has been shown to be more dangerous in terms of contributing to global warming than carbon dioxide (CO₂), especially in the first 20 years of its release into the atmosphere. Its accelerated emission increases the rate of global temperature increase and needs to be addressed immediately. Adsorption processes have been shown to be effective and efficient in mitigating methane emissions from the atmosphere by providing an enormous surface area for methane storage. Among all the adsorbents, MOFs were shown to be the best adsorbents for methane adsorption due to their higher favorable steric interactions, the presence of binding sites such as open metal sites, and hydrophobic pockets. These features may not necessarily be present in carbonaceous materials and zeolites. Although many studies have suggested that the main reason for the increased storage efficiencies in terms of methane in the MOFs is the high surface area, there was some evidence in certain research works that methane storage performance, as measured by uptakes and deliveries in gravimetric and volumetric units, was higher for certain MOFs with a lower surface area. This prompted us to find out the most significant property of the MOF, whether it be material-based or pore-based, that has the maximum influence on methane uptake and delivery, using a comprehensive statistical approach that has not previously been employed in the methane storage literature. The approach in our study employed various chemometric techniques, including simple and multiple linear regression (SLR and MLR), combined with different types of multicollinearity diagnostics, partial correlations, standardized coefficients, and changes in regression coefficient estimates and their standard errors, applied to both the SLR and MLR models. The main advantages of this statistical approach are that it is quicker, provides a deeper insight into experimental data, and highlights a single, most important, parameter for MOF design and tuning that can predict and maximize the output storage and capture performance. The significance of our approach is that it was modeled purely based on experimental data, which will capture the real system, as opposed to the molecular simulations employed previously in the literature. Our model included data from ~80 MOFs and eight properties related to the material, pore, and thermodynamics (isosteric adsorption energy). Successful attempts to model the methane sorption process have previously been conducted using thermodynamic approaches and by developing adsorption performance indicators, but these are either too complex or time-consuming and their data covers fewer than 10 MOFs and a maximum of three MOF properties. By comparing the statistical metrics between the models, the most important and statistically significant property of the MOF was determined, which will be crucial when designing MOFs for use in storing and delivering methane. Full article

Background: The problem of radon (Radon-222) in water is one of the daily health hazards faced by those in Ojo Axis, Nigeria. Therefore, continuous monitoring of radon contamination in different types of water is essential. In the present work, sixteen groundwater and surface-water samples (wells, boreholes, and sachets) were collected from six different locations within the Ojo Local Government area in Nigeria. The water samples collected were stored in 75 cl bottles that were already sterilized with distilled water to avoid contamination. Water samples were then taken to the laboratory for the analysis of radon levels using a RAD7, an active electronic device produced by the Durridge Company in the USA. The radon level in the water is higher than the safe limits of 11.1 Bq/L, as per EPA regulations, except for two sample points from the studied areas. The total annual effective doses from ingestion and inhalation for drinking and groundwater were higher than the safe limit of 0.1 mSv y⁻¹ that is recommended by the World Health Organization and the European Union Commission. Conclusions: The obtained results underline the importance of the development and/or updating of databases regarding radon levels in drinking and groundwater in the Ojo Local Government area in Nigeria. Full article

Currently, the challenges that analytical chemistry has to face are ever greater and more complex both from the point of view of the selectivity of analytical methods and their sensitivity. This is especially true in quantitative analysis, where various methods must include the development and validation of new materials, strategies, and procedures to meet the growing need for rapid, sensitive, selective, and green methods. In this context, given the International Guidelines, which over time, are updated and which set up increasingly stringent “limits”, constant innovation is required both in the pre-treatment procedures and in the instrumental configurations to obtain reliable, accurate, and reproducible information. In addition, the environmental field certainly represents the greatest challenge, as analytes are often present at trace and ultra-trace levels. These samples containing analytes at ultra-low concentration levels, therefore, require very labor-intensive sample preparation procedures and involve the high consumption of organic solvents that may not be considered “green”. In the literature, in recent years, there has been a strong development of increasingly high-performing sample preparation techniques, often “solvent-free”, as well as the development of hyphenated instrumental configurations that allow for reaching previously unimaginable levels of sensitivity. This review aims to provide an update of the most recent developments currently in use in sample pre-treatment and instrument configurations in the environmental field, also evaluating the role and future developments of analytical chemistry in light of upcoming challenges and new goals yet to be achieved. Full article

Lackawanna, a US county seat in Northeastern Pennsylvania has an estimated population of 216,000 in 2020. Over the years, it has been reported that several bodies of water found within the county have been contaminated with various metals. However, a comprehensive examination of the presence of these metals has not been conducted. The goal of this brief report was to perform a preliminary quantitative determination of the concentration of various metals found in Lackawanna County water sources. The sources analyzed included Lake Scranton, the Lackawanna River, the Griffin Reservoir, and Keyser Creek. Samples were taken from each source and analyses of copper, lead, zinc, iron, manganese, and cadmium using atomic absorption spectroscopy were performed. A copper concentration of 0.100 ppm was found in the Griffin Reservoir, and 0.380 ppm of iron was found in the Lackawanna River. The concentration of copper and iron in the Griffin Reservoir and Lackawanna River, respectively, were determined to be within safe levels according to guidelines set by the US Environmental Protection Agency. Full article

Raman spectroscopy (RS) is a spectroscopic method which indirectly measures the vibrational states within samples. This information on vibrational states can be utilized as spectroscopic fingerprints of the sample, which, subsequently, can be used in a wide range of application scenarios to determine the chemical composition of the sample without altering it, or to predict a sample property, such as the disease state of patients. These two examples are only a small portion of the application scenarios, which range from biomedical diagnostics to material science questions. However, the Raman signal is weak and due to the label-free character of RS, the Raman data is untargeted. Therefore, the analysis of Raman spectra is challenging and machine learning based chemometric models are needed. As a subset of representation learning algorithms, deep learning (DL) has had great success in data science for the analysis of Raman spectra and photonic data in general. In this review, recent developments of DL algorithms for Raman spectroscopy and the current challenges in the application of these algorithms will be discussed. Full article

Condition assessment of works of art created with oil media on paper could be a complex matter when presenting problems of damage due to the absorption of oil binders by the paper support, since they depend on several factors and occur in variable conditions. The present work refers to the results of an investigation on the effect of linseed oils on the color, opacity, morphology, tensile strength, and chemical properties of lignocellulosic papers, in comparison to that of pure cellulosic papers. Lignocellulosic papers are involved in research on new, yet significant, parameters that might influence the behavior of the oil-impregnated areas of the supports upon aging. The research was applied to mock-ups, made of two types of lignocellulosic paper impregnated with three types of linseed oil and subjected to accelaratated ageing in specific conditions of relative humidity and temperature in closed environment. The research involved colorimetry, opacity, tensile strength, pH measurements, SEM, FTIR, and VOC analysis with GC-MS. The results indicated that thermal-humid ageing caused the gradual darkening of the oil-impregnated mock-ups, alterations in opacity, and decrease of pH values, depending mainly on the formulation of linseed oil, as well as a reduction in tensile strength. FTIR analysis results indicated that the chemical changes that occur upon ageing supported the recorded optical and mechanical alterations, while VOC emissions are both associated with the paper type and the kinetics of degradation of the different types of linseed oil. Full article