Chemical Analysis Research Articles

Quantum Chemical Stability Analysis of Phthalocyanine Metal One-Dimensional Polymers with Bidentate Ligands.

The combination of metal-phthalocyanine complexes and axially coordinated organic molecules into polymer chains presents a significant challenge in the synthesis of hybrid materials. A calculated structure for one-dimensional coordinate polymers with N-donor ligands using ab initio (PM6) and DFT (LanL2Dz) methods is presented. DFT methods have shown that there is a linear, one-dimensional structure without distorted geometry for the two bipyridine ligands. The components of the proposed polymers consist of square-planar Zn complexes of phthalocyanine (PcZn) connected via bridging ligands (L). Electronic properties of the monomer PcZnL of zinc phthalocyanine with bidentate ligands have been analyzed using calculations based on density functional theory (B3LYP6-31G(d,p)). Molecular orbital calculations show that this connection between the metallomacrocycle and the conjugated ligand results in a small energy gap, promising molecularly active materials as conductors. The crystallographic reports indicate that obtaining this kind of polymer with the participation of Pc Zn and bidentate ligands is possible.

Mechanism study of Dual-Emission ratiometric fluorescent pH-Sensitive carbon quantum dots and its application on mornitoring enzymatic catalysis

Carbon dots (CQD) have received significant attention as a novel ratiometric fluorescent pH nanoprobe, owing to their favorable optical properties and excellent biocompatibility. Despite their appealing features, the precise mechanism behind the pH-sensitive photoluminescence of CQDs remains to be fully understood. This study endeavors to unravel the mechanism underlying the pH-responsive ratiometric fluorescence in dual-emission CQDs, synthesized through a one-step hydrothermal method using o-phenylenediamine and oxalic acid as precursors. The resultant CQDs exhibit inherent dual-emission at wavelengths of 383 nm and 566 nm, with the ratiometric fluorescence response tailored by the ratio of precursors, providing a robust tool for pH sensing across a range of 2 to 6. Detailed characterizations, including chemical, morphological, and optical analyses, alongside theoretical insights from time-dependent density functional theory (TD-DFT), elucidate the mechanism underlying the pH-dependent luminescence, attributed to the electron cloud transmission between amide and adjacent carboxyl groups on the CQD surface. The superior performance of these CQDs in real-time pH monitoring is demonstrated through their application in glucose oxidase-catalyzed reactions, showcasing their potential as efficient, reliable nanoprobes for biomedical research and diagnostic applications.

A high-throughput sample preparation approach for the determination of nonsteroidal anti-inflammatory drugs in urine samples through membrane-based microextraction employing a green supramolecular solvent

Nonsteroidal anti-inflammatory drugs (NSAIDs) are a class of drugs with antipyretic, analgesic, and anti-inflammatory effects widely used worldwide. This study aimed at developing an environmentally friendly and high-throughput sample preparation method for the determination of six NSAIDs in urine samples followed by high-performance liquid chromatography coupled to diode-array detection (HPLC-DAD). The experimental workflow consisted of hollow-fiber microporous membrane liquid-liquid extraction (HF-MMLLE) using a supramolecular solvent immobilized into the porous of polypropylene hollow membranes (1 cm length). These membranes were attached to a 96-well plate system to permit multiple extractions simultaneously. Under the optimized conditions, limits of detection (LODs) and limits of quantification (LOQs) ranged from 6.06 to 30.3 µg/L and from 20 to 100 µg/L, respectively. The linear ranges varied from 20 to 1000 µg/L for indomethacin and diclofenac, from 50 to 1000 µg/L for ketoprofen and ibuprofen, and from 100 to 1000 µg/L for naproxen and fenoprofen. The coefficients of determination (R²) ranged from 0.9735 to 0.9997. Intraday precision ranged from 6.13 to 20.11 %, interday precision varied from 2.87 to 20.72 %, and accuracy ranged from 92.49 to 126.89 %. Moreover, the recently proposed Sample Preparation Metric of Sustainability (SPMS) was employed to evaluate the greenness of the sample preparation technique resulting in a score of 8.0, which is highly satisfactory according to the concepts of green analytical chemistry.

Utilizing erythrosine B absorption spectrum shifts for quantitative determination of octreotide and bromocriptine in their pure forms and pharmaceutical formulations. Evaluation of the method greenness

In the present study, two drugs for treating acromegaly are investigated which are either synthetic growth hormone inhibiting hormone (GHIH) or dopamine receptor agonist. Octreotide (OCT) and bromocriptine (BCT) were quantified with a quick, simple, and sensitive spectrophotometric approach in their authentic forms and commercial dosage forms. This approach was based upon formation of ion pair complex between erythrosine B and investigated drugs in an aqueous buffered solution. For OCT determination the higher sensitivity was obtained using ΔA at 525 nm. On the other hand, BCT was estimated using the absorbance at 556 nm. Under optimal conditions for the reaction, construction of calibration curves were performed within concentration range of 0.4–4 µg ml−1 for OCT and 1–9 µg ml−1 for BCT with with low detection limits (0.094 and 0.235 µg ml−1) and low quantitation limits (0.29 and 0.71 µg ml−1) for OCT and BCT respectively. The developed approach was assessed for linearity, accuracy, precision, limits of detection, and limits of quantitation in compliance with ICH validation recommendations. The suggested approaches demonstrated good linearity, as evidenced by determination coefficients (r2) of 0.999 with a slope 0.14 for OCT and 0.9989 with a slope 0.06 for BCT. Additionally, the environmental friendliness of the investigated method was assessed with some of the recent green analytical chemistry metrics.

A Multiweek Experimental Project Bringing Real-World Lithium Batteries into a Third-Year Undergraduate Analytical Chemistry Laboratory

A Multiweek Experimental Project Bringing Real-World Lithium Batteries into a Third-Year Undergraduate Analytical Chemistry Laboratory

O-PTIR spectroscopy for characterizing active pharmaceutical ingredient specific particle size distributions of nasal spray suspension products

Evaluation of the particle size distribution (PSD) of active pharmaceutical ingredients (APIs) in nasal suspension products is challenging due to the presence of both API and excipients. To characterize these intricate formulations, it is essential to have sophisticated analytical methods that offer high spatial resolution and the ability to chemically pinpoint and map out the presence of API particles. However, such advanced techniques have not been documented for nasal formulations yet.In this proof-of-concept study, we investigated the utility of optical photothermal infrared spectroscopy (O-PTIR) to analyze the PSD of commercially available Nasonex® and its generic Azonaire® nasal mometasone furoate (MM) suspensions. Simultaneous O-PTIR and Raman spectra, as well as IR chemical maps, were collected from the particles in both formulations. Spatially resolved spectra from the particles confirmed the presence of peaks related to MM (1727 cm−1, 1661 cm−1, and 1122 cm−1) and excipient microcrystalline cellulose (MCC) (1061 cm−1). The PSD of MM particles was characterized using chemical maps specific to MM (1661 cm−1) and automated imaging. Results confirmed that the PSD of both formulations were comparable. Spectral analysis also revealed the presence of free MM, free MCC, and particles containing co-localized MM and MCC.For suspension-based nasal products, O-PTIR enables the measurement of API PSD, which is critical for formulators in developing nasal suspension products. This approach holds potential as an innovative complimentary analytical tool that could diminish the need for extensive clinical endpoint bioequivalence studies when evaluating the comparability of generic and brand-name nasal suspension products.

Virtual reality inspection of chromatin 3D and 2D data

Understanding the packing of long DNA strands into chromatin is one of the ultimate challenges in genomic research. An intrinsic part of this complex problem is studying the chromatin’s spatial structure. Biologists reconstruct 3D models of chromatin from experimental data, yet the exploration and analysis of such 3D structures is limited in existing genomic data visualization tools. To improve this situation, we investigated the current options of immersive methods and designed a prototypical VR visualization tool for 3D chromatin models that leverages virtual reality to deal with the spatial data. We showcase the tool in three primary use cases. First, we provide an overall 3D shape overview of the chromatin to facilitate the identification of regions of interest and the selection for further investigation. Second, we include the option to export the selected regions and elements in the BED format, which can be loaded into common analytical tools. Third, we integrate epigenetic modification data along the sequence that influence gene expression, either as in-world 2D charts or overlaid on the 3D structure itself. We developed our application in collaboration with two domain experts and gathered insights from two informal studies with five other experts.

A smart mask for exhaled breath condensate harvesting and analysis.

Recent respiratory outbreaks have garnered substantial attention, yet most respiratory monitoring remains confined to physical signals. Exhaled breath condensate (EBC) harbors rich molecular information that could unveil diverse insights into an individual's health. Unfortunately, challenges related to sample collection and the lack of on-site analytical tools impede the widespread adoption of EBC analysis. Here, we introduce EBCare, a mask-based device for real-time in situ monitoring of EBC biomarkers. Using a tandem cooling strategy, automated microfluidics, highly selective electrochemical biosensors, and a wireless reading circuit, EBCare enables continuous multimodal monitoring of EBC analytes across real-life indoor and outdoor activities. We validated EBCare's usability in assessing metabolic conditions and respiratory airway inflammation in healthy participants, patients with chronic obstructive pulmonary disease or asthma, and patients after COVID-19 infection.

Digestive utilization of Sahelian forages associated with cowpea haulms (Vingna unguiculata) and blood profile in Arabic rams

Digestive utilization of sahelian forages associated with Vingna unguiculata and blood profile study was conducted in scientific garden of the University of Sciences and Technology, Ati (JSUSTA). Three forages were used to assess in vivo digestibity in eighteen (18) rams weighing around 31.83±3.02 kg and displayed individually in metabolic cages in six (6) groups of three (3) animals. Control groups received 1000g of feed made up of Brachiaria deflexa, Dactyloctenium aegyptium and Echinocloa colona. While, experimental groups received basal feeds associated with 30% of Vingna unguiculata. The experiment was preceded by 14 days adaptation and 7 days of data collection during which, hundred (100g) grams of feeds and feces as well as urine (10 ml) were collected for chemical analysis and digestibility assessment. At the end of experimentation, two (2) ml of blood was collected from each animal before and after feeding for blood profile analysis. The results showed that the association of 30% Vingna unguiculata have significantly (p<0.05) increased intake of D. aegyptium and B. deflexa in Arab rams. In vivo digestibility of E. colona was significantly (p<0.05) higher in rams when associated or no with 30% of Vingna unguiculata. Blood profile analysis showed that E. colona associated with 30% of Vingna unguiculata induced significant (p<0.05) increase in blood protein, globulin and cholesterol concentration in Arabic rams.

Development and Characterization of N2O-Plasma Oxide Layers for High-Temperature p-Type Passivating Contacts in Silicon Solar Cells.

Full-area passivating contacts based on SiOx/poly-Si stacks are key for the new generation of industrial silicon solar cells substituting the passivated emitter and rear cell (PERC) technology. Demonstrating a potential efficiency increase of 1 to 2% compared to PERC, the utilization of n-type wafers with an n-type contact at the back and a p-type diffused boron emitter has become the industry standard in 2024. In this work, variations of this technology are explored, considering p-type passivating contacts on p-type Si wafers formed via a rapid thermal processing (RTP) step. These contacts could be useful in conjunction with n-type contacts for realizing solar cells with passivating contacts on both sides. Here, a particular focus is set on investigating the influence of the applied thermal treatment on the interfacial silicon oxide (SiOx) layer. Thin SiOx layers formed via ultraviolet (UV)-O3 exposure are compared with layers obtained through a plasma treatment with nitrous oxide (N2O). This process is performed in the same plasma enhanced chemical vapor deposition (PECVD) chamber used to grow the Si-based passivating layer, resulting in a streamlined process flow. For both oxide types, the influence of the RTP thermal budget on passivation quality and contact resistivity is investigated. Whereas the UV-O3 oxide shows a pronounced degradation when using high thermal budget annealing (T > 860 °C), the N2O-plasma oxide exhibits instead an excellent passivation quality under these conditions. Simultaneously, the contact resistivity achieved with the N2O-plasma oxide layer is comparable to that yielded by UV-O3-grown oxides. To unravel the mechanisms behind the improved performance obtained with the N2O-plasma oxide at high thermal budget, characterization by high-resolution (scanning) transmission electron microscopy (HR-(S)TEM), X-ray reflectometry (XRR) and X-ray photoelectron spectroscopy (XPS) is conducted on layer stacks featuring both N2O and UV-O3 oxides after RTP. A breakup of the UV-O3 oxide at high thermal budget is observed, whereas the N2O oxide is found to maintain its structural integrity along the interface. Furthermore, chemical analysis reveals that the N2O oxide is richer in oxygen and contains a higher amount of nitrogen compared to the UV-O3 oxide. These distinguishing characteristics can be directly linked to the enhanced stability exhibited by the N2O oxide under higher annealing temperatures and extended dwell times.

Research on stochastic properties of time series data on chemical analysis of cast iron

Research on stochastic properties of time series data on chemical analysis of cast iron

Signals of soil formation during pre-glacial maximum on the byers peninsula (maritime antarctica)

The Maritime Antarctic is one of the most sensitive regions on Earth to warming, recording permafrost degradation and glacial retreat in the last 10 kyr. The timing of deglaciation and the pedological implications are still poorly elucidated in many ice-free areas of the Antarctic. The severity of the Last Glacial Maximum (LGM) across the Maritime Antarctic has limited paleoenvironmental records of pre-LGM terrestrial signals, constraining knowledge of climate trends in the Late Pleistocene. Byers Peninsula is one of the most extensive ice-free areas in the Maritime Antarctic. So, we hypothesized that soils in Byers Peninsula host Pleistocene sedimentological and pedological evidence of landscape evolution. This study investigated soil genesis in Byers Peninsula. Radiocarbon and OSL dates provided a chronology of nine soil profiles. Morphological, physical, and chemical analysis characterized soil formation. Isotopic composition of organic matter tracked the main photosynthetic processes. Endolithic soil organic matter in a pre-LGM soil indicates soil genesis at 31,690 cal yr BP, much earlier than the common age models of approximately 10,000 cal yr BP in previous studies. Burial and 14C ages in Cryosols formed on beach sediments above 70 m and on cliffs suggest marine terrace uplift and soil genesis in cliffs during the Late Pleistocene-Early Holocene. Younger Cryosols and Leptosols soils formed on raised beaches in Late Holocene. These findings suggest an older glacial retreat in the Maritime Antarctic. Soil proxies in potential pre-LGM ice-free areas are promising tools for paleoenvironmental reconstructions of the Maritime Antarctic.

Evaluation of rheological and microstructural behavior of modified asphalt binder with chitosan derived from shrimp shell powder

Chitosan derived from shrimp shells (SSPCH) was used for the first time as a biological biopolymer to modify the properties of bitumen across high, medium, and low-temperature ranges. Therefore, physical tests (penetration, softening point, and ductility) and rheological tests (RV, DSR, MSCR, LAS, and BBR) were conducted along with morphological and microstructural analyses, on modified bitumen with 2 %, 4 %, 6 %, and 8 % SSPCH. Chemical analysis revealed that bitumen and SSPCH interacted physically during the mixing process, while no chemical reaction was observed. Moreover, the thermal sensitivity of the modified bitumen was enhanced by decreasing the penetration degree and increasing the softening point. SSPCH improved the properties of modified bitumen as a result of its porous structure and asphaltene absorption, as well as its structural similarity to bitumen and ability to absorb the light components of bitumen with its heavy components. Increasing the SSPCH dose in bitumen improves its resistance to deformation and recoverability by increasing the viscous phase and decreasing the elastic phase, resulting in increased stiffness. The findings also revealed that the addition of 6 % SSPCH yielded the best performance against rutting failures. Generally, SSPCH incorporation significantly improved bitumen performance in different temperature ranges. By adding 8 % SSPCH, the highest resistance to rutting occurred. However, the phase separation between SSPCH and bitumen exceeded the suitable range. Hence, 6 % SSPCH is useful in the bitumen mixture for areas at high temperature. Also, to prevent fatigue and cracking damage, it is recommended to limit the dose of SSPCH to 4–6%.

Hyperspectral Imaging Technique to Characterize Digestate and Visualize Physical Impurities in Anaerobically Digested Biowaste.

Methods used to monitor anaerobic digestion (AD) indicators are commonly based on wet chemical analyses, which consume time and materials. In addition, physical disturbances, such as floating granules (FGs), must be monitored manually. In this study, we present an eco-friendly, high-throughput methodology that uses near-infrared hyperspectral imaging (NIR-HSI) to build a machine-learning model for characterizing the chemical composition of the digestate and a target detection algorithm for identifying FGs. A total of 732 digestate samples were used to develop and validate a model for calculating total nitrogen (TN), total organic carbon (TOC), total ammonia nitrogen (TAN), and chemical oxygen demand (COD), which are the chemical indicators of responses to disturbances in the AD process. Among these parameters, good model performance was obtained using the dried digestates data set, where the coefficient of determination (R2test) and the root-mean-square error (RMSEtest) were 0.82 and 1090 mg/L for TOC, and 0.86 and 690 mg/L for TN, respectively. Furthermore, the unique spectral features of the FGs in reactors with a lipid-rich substrate meant that they could also be identified by the HSI system. Based on these findings, developing NIR-HSI solutions to monitor the digestate properties in AD plants has great potential for industrial application.

Recent advances in solid phase microextraction with various geometries in environmental analysis.

Solid phase microextraction (SPME) has emerged as a versatile sample preparation technique for the preconcentration of a broad range of compounds with various polarities, especially in environmental studies. SPME has demonstrated its eco-friendly credentials, significantly reducing the reliance on solvents. The use of biocompatible materials as a coating recipe facilitates the acceptance of SPME devices in analytical chemistry, primarily in the monitoring of environmental pollutants such as persistent organic pollutants (POPs), volatile organic compounds (VOCs), and pesticides from the various environmental matrices. During the last few years, investigators have reported an improvement in the SPME enrichment technique after changing the coating recipe, geometries, and sampling procedure from the complex matrices. Furthermore, the development of various geometries of SPME with large surface areas has enhanced the extraction efficiency of environmental pollutants. As a miniaturized sample preparation technique, SPME significantly reduces the solvent usage, suggesting a potential platform for green chemistry-based research for water, air, and soil analysis. This review article summarizes the evolution of SPME, its various modes, the application of SPME, recent innovations, and prospects for the determination of water, air, and soil pollution. The advantages and disadvantages of SPME in comparison to other extraction techniques have been discussed here. This review serves as a valuable resource for investigators working in sustainable environmental research.

Nitrogen recovery from biogas slurry with high ammonia nitrogen concentration through struvite precipitation utilizing acid leaching solution of collophanite tailings

ABSTRACT The high concentration of ammonia nitrogen (NH4+) and chemical oxygen demand (COD) in biogas slurry pose great challenges to the efficiency of traditional wastewater treatment systems. Collophanite tailings are solid waste, characterized by significant concentrations of phosphorus (PO43-) and magnesium (Mg2+), represent a potential resource for the reduction and recovery of NH4+ in biogas slurry via struvite precipitation. This study systematically explored the optimal leaching parameters employing sulfuric acid for the extraction of PO43− and Mg2+ from collophanite tailings. The effect of [PO43-]:[NH4+] molar ratio and pH on the recovery of NH4+ in biogas slurry was investigated. The physicochemical properties of the precipitates were confirmed using X-ray diffraction (XRD), scanning electron microscopy (SEM), and chemical analysis. Results suggested that the highest removal efficiency of NH4+ (88.5%) was achieved when employing a [PO43-]:[NH4+] molar ratio of 1.0 at pH 9.5. Evaluation of effluent quality demonstrates a significant enhancement in the biodegradability of the treated biogas slurry, evidenced by an increase in the COD/TN ratio increased from 2.1 to 10.4. Economic analysis shows that the net income would be approximately 21.33 USD/m3 for proposed produces. These findings underscore the potential of utilizing collophanite tailings for NH4+ recovery from biogas slurry.

Molecular docking and DFT study of antiproliferative ribofuranose nucleoside derivatives targeting EGFR and VEGFR2in cancer cells

Antimetabolites are the most effective chemotherapeutics for treating cancer. They have exerted their anticancer effects by interfering with DNA synthesis. Recently, interest in modified nucleoside analogues has grown due to their superior efficiency. Nucleoside analogue derivatives have emerged as crucial candidates for cancer treatment due to their ability to target the cells responsible for cancer within the body specifically. The ability of nucleoside analogues derivatives to target specific molecular pathways has reduced toxicity and increased efficiency compared to traditional chemotherapy drugs. Nucleoside analogues have interfered with physiological nucleosides and induced cytotoxicity in cancerous cells. In this investigation, derivatives of ribofuranose nucleoside analogues have been designed. Density functional theory (DFT) calculations have been performed at the B3LYP/6–311 G(d,p) level. The designed molecules have been characterized by UV/Vis spectroscopy using the CPCM model in DMSO solvent, and molecular structural parameters, such as HOMO/LUMO and MEPS, have been determined. Derivative d1m has exhibited a high energy gap and low absorption energy compared to the other derivatives. Molecular docking of the designed molecules (d1o-d2m) has been performed with the EGFR and VEGFR2 proteins. d2o has shown good binding energy with the EGFR protein, while d1o has shown good results with VEGFR2. Global chemical parameters and NBO analysis have been conducted to investigate the derivatives charge transfer properties and chemical reactivity. NBO analysis has provided information about the donor and acceptor parts within a molecule, while global chemical parameters have given insights into the reactivity, stability, and solubility of the molecules. It has been found that the derivatives are more chemically reactive, thermodynamically stable, and have better binding affinity than the parent molecule. Based on the analysis, the drug interaction with the cancer-causing protein makes it more effective for cancer treatment.

Laboratory Test of a Gear Hydraulic Pump during the Application of an Environmentally Friendly Hydraulic Fluid with Constant Pressure and Temperature

The use of environmentally friendly hydraulic fluids is frequently influenced by the temperature reached in the hydraulic circuit. This paper presents an analysis of the effect of temperature on the lifetime of the hydraulic fluid and the hydraulic pump. The test was carried out by continuous loading with a pressure of 21 MPa and a temperature of 96 °C for 100 h. A pressure valve was used for the continuous loading and the temperature was maintained using a cooler. At intervals of 25 h, the flow characteristics of the hydraulic pump were measured and oil sampling was carried out. Subsequently, a comprehensive chemical and physical analysis was carried out. In the present paper, a comprehensive analysis of the influence of eco-friendly hydraulic fluid on the operation of a gear hydraulic pump has been carried out. The study itself did not show the negative influence of the eco-friendly hydraulic fluid on the operation of the gear hydraulic pump. It can be expected that the results of the study will enable the use of eco-friendly hydraulic fluids in environmentally sensitive areas.

Measuring meaningful learning through the experience of chemistry education students' in the basics of analytical chemistry practicum

Measuring meaningful learning through the experience of chemistry education students' in the basics of analytical chemistry practicum

G-CovSel: Covariance oriented variable clustering

Dimensionality reduction is an essential step in the processing of analytical chemistry data. When this reduction is carried out by variable selection, it can enable the identification of biochemical pathways. CovSel has been developed to meet this requirement, through a parsimonious selection of non-redundant variables. This article presents the g-CovSel method, which modifies the CovSel algorithm to produce highly complementary groups containing highly correlated variables. This modification requires the theoretical definition of the groups' construction and of the deflation of the data with respect to the selected groups. Two applications, on two extreme case studies, are presented. The first, based on near-infrared spectra related to four chemicals, demonstrates the relevance of the selected groups and the method's ability to handle highly correlated variables. The second, based on genomic data, demonstrates the method's ability to handle very highly multivariate data. Most of the groups formed can be interpreted from a functional point of view, making g-CovSel a tool of choice for biomarker identification in omics. Further work will be carried out to generalize g-CovSel to multi-block and multi-way data.