International Journal of Analytical Chemistry最新文献

Near-infrared (NIR) spectroscopy data encounter challenges in data processing such as peak overlapping, information redundancy, and background or noise, which complicate the evaluation of weak differences among similar samples. Therefore, accurately identifying these differences and assessing similarities are essential in practical applications for sample classification and further replacement of raw materials in the product formulation. In this work, 32 data preprocessing strategies of NIR data were systematically combined for comprehensive comparison, and 11 methods for similarity analysis were evaluated to attain optimal performance. Using the rationality of similarity evaluation as the assessment criterion, the combination of NIR data pretreatment methods of "standard normal variate (SNV) + first-order derivative by Savitzky-Golay (1D/SG) + maximum-minimum scaling (MMS) + spectral similarity by combinatorial strategy (SS/CS)" is ultimately preferred as the most effective combination for similarity evaluation. It uses SNV transformation, 1D/SG, MMS, and scattering correction to eliminate the scattering effect, enhance the signal-to-noise ratio (SNR) of the distinction of overlapping peaks, and improve data comparability. After this, the widely used methods for similarity evaluation were employed for comprehensive analysis and comparison of the rationality, such as Euclidean distance, correlation coefficient, and divergence information. The evaluation strategy proposed in this work can effectively distinguish the difference among the tobacco samples existing in 10 different categories. The similarity among typical samples in the same class is above 0.9, while the values in different classes are below 0.7. In real applications for method validation, recognition precision of tobacco samples with blending of interfering mixtures reaches 5%, which is conducted using complex tobacco materials for formulation replacement and optimization. The satisfactory results introduce robust and CS that outperforms traditional single-method approaches to resolve weak spectral differences through real-world tobacco formulation replacement applications. It can be widely used in the areas related to NIR for similarity evaluation, such as pharmaceuticals, food quality control, and environmental monitoring.

Background: Reliable determination of calcium in pharmaceuticals is crucial for quality control, yet conventional methods often rely on synthetic chelating agents such as EDTA, which raise environmental and safety concerns. Curcumin, the principal polyphenolic compound in Curcuma longa (turmeric), exhibits strong metal-chelating properties through its β-diketone structure. This study explores the use of curcumin as a natural and sustainable chelating agent for the spectrophotometric determination of calcium in pharmaceutical formulations.

Method: Curcumin was extracted from turmeric rhizomes collected from different altitudes in Nepal using ethanol and was allowed to form a stable color complex with various calcium-containing drugs, such as calcium gluconate, calcium lactate, and calcium docusate. The method was optimized by adjusting reagent volume, pH, and buffer volume. Validation was carried out according to ICH guidelines, evaluating linearity, precision, accuracy, and robustness. The environmental impact was assessed using Green Analytical Procedure Index, Analytical Eco-Scale, and AGREES tools. The Click Analytical Chemistry Index was used to analyze overall sustainability, while the Carbon Footprint Reduction Index was applied to evaluate the prime environmental impact of the already developed analytical laboratory procedures.

Results: The highest curcumin yield was from the Kaski region. The optimized method produced a stable yellow-orange complex with maximum absorbance at 430 nm. It demonstrated high precision (%RSD < 2%), accuracy (recovery: 101.63% and 102.01%), and robustness with a stable reaction lasting up to 4 h. The environmental assessment confirmed its sustainability and eco-friendliness, with a very good score reflecting minimal solvent use and no hazardous waste.

Conclusions: This study successfully developed a green, cost-effective, and reliable method for calcium analysis in pharmaceutical products using curcumin as a natural reagent. Its simplicity and environmental sustainability make it a promising alternative to conventional techniques for calcium analysis.

Nirmatrelvir, a key antiviral agent in the treatment of COVID-19, requires accurate and reliable monitoring of drug levels to optimize therapeutic efficacy. In this study, we developed and validated a sensitive and specific LC-MS/MS method for the quantification of nirmatrelvir in human plasma. The method includes nirmatrelvir-D9 as an internal standard, with quantification achieved using selected reaction monitoring in positive electrospray ionization mode, targeting m/z 500.3 ⟶ 110.1 for nirmatrelvir and m/z 509.3 ⟶ 110.1 for nirmatrelvir-D9. Sample preparation involved a simple phospholipid removal step using 96-well plate and automated liquid handler, which improved efficiency in a high-throughput process. The validated method, following international bioanalytical guidelines, demonstrated a linear range from 10.9 to 3013 ng/mL. Intra- and interassay precisions were both below 15%. All validation tests meet the criteria for matrix effect, carryover, dilution integrity, and stability. The method offers a rapid analysis time of 2 min per sample and provides highly accurate, reproducible results, making it a valuable tool for evaluating the pharmacokinetics of nirmatrelvir in clinical settings.

Trial registration: ClinicalTrials.gov identifier: NCT05041907.

Barley (Hordeum vulgare) is one of the earliest cereal crops cultivated in Ethiopia. Since barley and malt are widely consumed globally, conducting a spatiotemporal quality assessment is crucial to mitigate potential health risks for consumers. Therefore, this study investigated the physicochemical quality and the levels of selected metals in barley grown primarily for brewing purposes, as well as in the resulting malt, in the Gondar Zones of Ethiopia's Amhara Region. The investigation involved sample digestion with nitric and perchloric acids, and the resulting digestates were analyzed using an atomic absorption spectrophotometer equipped with a deuterium arc background corrector. The results indicate that, except for copper and nickel in barley grains, the concentrations of iron, zinc, and manganese in both barley and malt samples were approximately within the allowable limits established by the Food and Agriculture Organization (FAO) and the World Health Organization (WHO). The average contents in barley were 112.3 ± 7.3, 10.4 ± 1.7, 20.9 ± 3.0, 26.6 ± 2.3, and 11.6 ± 3.4 mg/kg for iron, copper, zinc, manganese, and nickel, respectively. The corresponding values in malt samples were 92.0 ± 5.9, 10.7 ± 4.2, 26.2 ± 5.2, 26.7 ± 6.2, and 18.0 ± 7.5 mg/kg, respectively. Although most trace metal levels and physicochemical qualities of barley and malt in this study fell within the acceptable ranges established by the European Brewing Convention (EBC), FAO, and WHO, continuous monitoring of trace metal levels in indigenous barley and its malt products is recommended to avoid potential health risks to consumers.

Water is essential for human life, yet contaminated drinking water poses significant health risks, leading to various waterborne diseases. The quality of drinking water is primarily determined by its physicochemical and biological characteristics, making regular monitoring crucial. However, no prior studies have assessed the physicochemical properties of drinking water in Malle Woreda, South Omo Zone, southern Ethiopia. This study aims to evaluate the levels of selected physicochemical parameters, including pH, temperature, free chlorine, combined chlorine, nitrate (NO₃ ^-), nitrite (NO₂ ^-), ammonia (NH₃), turbidity, electrical conductivity (EC), and fluoride (F^-), in drinking water sources within the Malle district. Three water samples were randomly collected from three different kebeles: Gento, Kalendo, and Asheker. The results indicate that the measured values for temperature (25.0°C-27.23°C), pH (7.33-8.81), EC (102.4-124.1 µS/cm), turbidity (< 5 NTU), NH₃ (0-0.1 mg/L), NO₃ ^- (1.0-1.1 mg/L), NO₂ ^- (0.1-1.0 mg/L), F^- (0.6-1.5 mg/L), free chlorine (0.1 mg/L), and combined chlorine (0-0.1 mg/L) generally meet the standards set by the World Health Organization (WHO) and the Ethiopian Standards Agency (ESA). Overall, the findings suggest that the protected spring water in Malle Woreda is suitable for drinking purposes. Compared to WHO and ESA guidelines, as well as studies from other regions, the drinking water in this area exhibits good physicochemical properties. Regular monitoring and management of water sources remain essential to ensure long-term water safety. Therefore, this study serves as a stepping stone for further investigations into additional water quality parameters.

In this study, the establishment and validation of a stable reversed-phase high-performance liquid chromatography (RP-HPLC) method for the concomitant estimation of the two drugs in dosage forms are presented. Method optimization was achieved by response surface methodology (RSM) using Design Expert Software 13, taking into account the special physicochemical characteristics of metoclopramide (MET) (a moderately polar molecule, pKa 9.5) and camylofin (CAM) (a less polar, hydrophobic molecule, pKa 8.7). Chromatographic resolution was achieved on a phenyl-hexyl column under isocratic mobile phase mode in which methanol and 20 mM ammonium acetate buffer (pH 3.5) were used to provide maximum analyte interaction and resolution. The method was found to have good linearity for both analytes (R ² > 0.999) over the concentration ranges studied. Limits of detection were 0.23 and 0.15 μg/mL for MET and CAM, respectively, and corresponding limits of quantification were 0.35 and 0.42 μg/mL, respectively. Recovery tests gave high precision values of 98.2%-101.5%, while intra- and inter-day precision in relative standard deviation (RSD) was below 2%. The method was effectively applied for the analysis of commercial tablet formulations, confirming its reliability and suitability for routine quality control and regulatory analyses. Overall, the validated RP-HPLC method provides a sensitive, accurate, and efficient means of simultaneous determination of MET and CAM in pharmaceutical dosage forms.

The occurrence of crystallization plugging in the tunnel drainage system will lead to cracking and leakage of the tunnel lining. Therefore, it is very important to take effective measures to prevent the blockage of the crystallization pipe of the tunnel drainage system and ensure the safety and stability of the lining structure during the operation of the tunnel. In this study, we conducted field surveys and laboratory tests to analyze the relationship between the crystals in the Yijun tunnel blind pipeline and the concentration of various ions in the groundwater. X-ray diffraction (XRD) analysis confirmed that the main component of the crystalline sediment was calcium carbonate. The formation mechanism of crystallization was explored by using the environmental water chemical equilibrium software, Visual MINTEQ 3.1. Considering that the preparation of cleaning agent has less corrosive effect on tunnel concrete materials, the cleaning efficiency test of various acid cleaning agents on tunnel crystals was carried out to determine the optimal concentration of cleaning solution. Finally, it is determined that the mixture of formic acid: citric acid: corrosion inhibitor: surfactant: water = 1:0.5: 0.5:0.5: 5 is used as the cleaning agent of tunnel blind pipe. The experimental results show that the cleaning agent has a 92.4% CaCO₃ dissolution rate, and the pH is controllable (4.7-7.9), which meets the environmental protection standards, and has little damage to the concrete (strength loss of 3.4 Mega Pascal, control group 6.2 Mega Pascal).

The demand for cobalt-based alloys has been steadily increasing due to advancements in industrial and cutting-edge technologies, particularly in metallurgy, where cobalt plays a crucial role in high-performance superalloys, battery production, and corrosion-resistant materials. Consequently, the concentration of cobalt ions in wastewater and environmental samples has exceeded permissible levels, raising significant ecological concerns. This study presents the development of an efficient method for the determination of cobalt(II) ions using a silver/mercury film working electrode (Hg(Ag)FE) modified with the organic dye ortho-nitrosophenol (o-NF) through cyclic voltammetry (CV). Optimization of the experimental conditions revealed that an acetate buffer (0.1 M, pH 5.1) served as the supporting electrolyte, with an accumulation time of 10 s and a concentration of 2.0 μM o-nitrosophenol. The preconcentration conditions were adjusted to enhance the sensitivity and selectivity for cobalt(II) ion detection. The method exhibited a linear relationship in the concentration range of 0.040-0.160 μM (R ² = 0.9863), with a limit of detection (LOD) of 0.010 μM and a limit of quantification (LOQ) of 0.034 μM for Co(II) ions. The proposed method was successfully applied to the analysis of water samples from the Aydar-Arnasoy Reservoir, and the accuracy of the results was statistically validated using Student's t-test. These findings demonstrate the potential of the developed method as an effective tool for environmental monitoring and the determination of cobalt ions in ecological protection initiatives.

[This corrects the article DOI: 10.1155/2024/3374034.].

A significant improvement in sustainability and efficiency is achievable through green and white chemistry. As part of this study, sustainability assessment tools were used to assess the environmental impact and practicality of an innovative, straightforward RP-UPLC method to analyze cyclopentolate (CLO) and its organic impurities simultaneously in pure and ophthalmic solutions at the same time. An optimization strategy based on Box-Behnken design was employed to minimize experimental runs while optimizing chromatographic conditions. Using this design, four critical variables were evaluated comprehensively-ethanol percentage in the mobile phase, pH, column temperature, and flow rate-on chromatographic responses such as retention time, resolution between CLO and impurity, and theoretical plate count. As a result of desirable and overlay plots, an optimal condition was selected: 65:25, v/v, ethanol and buffer, pH 4.25, 0.3 mL/min flow rate, and 4°C and 25°C sample and column oven temperatures, respectively, and the main peak retained for a little more than 3 min. The calibration curves for CLO and impurities at concentrations from 5 to 50 μg/mL and 1 to 20 μg/mL showed a correlation value of 0.9998. Recoveries are ±15% of the actual amounts, which is acceptable. RP-UPLC has been extensively designed for the coincidental estimation of anticholinergic drugs and their impurities. A combination of white and green tools was used to assess the method's environmental impact. ICH guidelines have been followed to validate the suggested strategy. This approach offers a reliable, fast, and eco-friendly solution for routine pharmaceutical quality control of anticholinergic agents.