International Journal of Analytical Chemistry最新文献

Amyloid nanofibrils are long and thin strands with cross β structures associated by hydrogen bonds. These structures can be formed under suitable conditions commonly at low pH and high temperatures. Fibrillated pinto bean protein isolate (FPBPI) was made by heating pinto bean protein at 85°C in an acidic condition while gently stirring at initial protein solution concentrations of 4 mg/mL, 13 mg/mL, and 21 mg/mL. Freeze-dried FPBPI's physicochemical, structural, and thermal characteristics were assessed, and they were compared with a native pinto bean protein isolate (PBPI) as a control. An increase in Congo red spectral absorption at 544 nm was observed following the fibril formation process. The largest concentration of freeze-dried fibrillated protein exhibited the highest Congo red spectral absorption. Fibrillar proteins' Fourier transform infrared (FTIR) spectrograms with lower wave numbers were seen than the native protein. For native PBPI, transmission electron microscopy (TEM) images were globular in shape, but they changed to long and curly morphologies in fibrillated proteins. FPBPI has a lower melting enthalpy than native protein when measured by differential scanning calorimetry (DSC). With the rising initial protein content, the enthalpy rose. Concurrently, semicrystalline structure for native and fibrillated pinto bean proteins was revealed by X-ray diffraction (XRD) findings. As the original protein concentration grew, so did the crystallinity intensity. Water-holding capacity (WHC) and oil-holding capacity (OHC) of freeze-dried FPBPI were higher than those of native protein. So, fibrillation of pinto bean protein helped it to serve as a good thickener in food industries.

Based on the effectiveness, measurability, and traceability of the quality marker (Q-marker) theory of traditional Chinese medicine, the Q-marker of Lycii Cortex (LC) was preliminarily predicted and analyzed. A UPLC-Q-TOF-MS qualitative analysis method for LC samples was established. A total of 44 LC chemical components, 16 plasma prototype components, 25 urine prototype components, and 27 fecal prototype components were identified. At the same time, the "component-target-disease" network diagram was constructed by network pharmacology to predict the potential active components of LC. A UPLC-MS/MS quantitative analysis method was established to determine the contents of 11 components such as kukoamine A in 35 batches of LC from seven producing areas. Principal component analysis, orthogonal partial least squares discriminant analysis, and other mathematical analysis methods were used to screen the differential components. Based on the comprehensive consideration of the Q-marker traceability, transitivity, specificity, effectiveness, and measurability, kukoamine A and kukoamine B were preliminarily predicted as LC potential Q-markers, and the high-quality producing area was determined to be Chengcheng County, Weinan City, Shaanxi Province. The prediction analysis of the LC Q-marker provides a reference for the comprehensive control of the quality of LC medicinal materials and also lays a foundation for the research and exploration of the substance basis and mechanism of action of LC.

Herein, a micro-solid-phase extraction (μSPE) method was developed using a pipette tip for rutin extraction, employing activated hollow carbon nanospheres (HCNSs) as the sorbent. Characterization of the activated carbon nanospheres through TGA, FTIR, and SEM analysis confirmed the success of the activation process. The study demonstrated the efficacy of PT-μSPE in rutin extraction under pH 2 conditions with a standard concentration of 2 mg·L^-1. The optimal mass of HCNSs was found to be 2 mg, and a loading volume of 500 μL resulted in the maximum recovery of rutin. Propan-2-ol was the best elution solvent with 15 aspirating/dispensing cycles. The correlation of determination (R ²) for the calibration curve was found to be 0.9991, and the LOD and LOQ values were 0.604 and 1.830 mg·L^-1, respectively. The applicability of the method was demonstrated by extracting rutin from a complex Moringa oleifera leaf extract with the relative standard deviation (RSD) of 3.26%, thereby validating this method as feasible for the extraction of useful bioactive compounds from complex plant samples.

In this study, spectrophotometric determination of donepezil and rivastigmine in healthy human urine samples was carried out by the statistical method. Partial least squares (PLS) and principal component regression (PCR) from multivariate calibration methods were used to evaluate the data obtained from the UV-Vis spectroscopy analysis of the urine sample. Mixtures of each early substance were prepared prior to urine sample analysis, and simultaneous determination of donepezil and rivastigmine was performed on the established chemometric model without any prior separation. The calibration curves of each drug were analyzed, and linearity values were also analyzed. For donepezil and rivastigmine, they were 0.9989 and 0.9997, respectively, and were linear over the concentration range of the synthetic mixture. When both chemometric methods (PLS and PCR) were evaluated in terms of accuracy and reproducibility, very high recoveries and small standard deviations were determined. In the PLS method, the standard error of prediction (SEC), the sum of the prediction residual errors (PRESS), the limit of quantitation (LOQ), and the limit of detection (LOD) values were 0.015, 0.0030, 0.067, 0.24, 0.018, 0.0042, 0.089, and 0.301 for donepezil and rivastigmine, respectively. In the PCR method, SEC, PRESS, LOD, and LOQ values are 0.016, 0.0054, 0.066, and 0.23 for donepezil and 0.022, 0.0062, 0.091, and 0.300 for rivastigmine. Chemometrics is used for speed, simplicity, and reliability. The proposed methods have been successfully applied to a sample of urine.

To explore the relationship between unsaturated fatty acid (UFA) content and parameters for microwave extraction, multimaterial and multiparameter testing was conducted in which five kinds of materials with different UFA contents (potato, wheat, corn, soybean, and peanut) were selected for the experiment. Four factors, namely, extraction temperature (X ₁), extraction time (X ₂), proportional volume of acetone (X ₃), and liquid-to-solid ratio (X ₄), were screened for their significant effects by using Prob > |T| values from the Plackett-Burman experiment. A microwave extraction orthogonal experiment with four factors and five levels was designed separately using Design-Expert 8.05 software and them concentrated. Microwave-accelerated methyl esterification was then performed, and the UFA content was determined via gas chromatography (flame ionization detector). The optimal extraction conditions (X ₁, X ₂, X ₃, X ₄) and the optimal UFA content of potato were 80.68°C, 10.74 min, 0.80, 3.25 mL × g^-1, 1.08%; wheat: 80.81°C, 10.54 min, 0.80, 20.91 mL × g^-1, 2.26%; corn: 81.18°C, 9.93 min, 0.80, 50.94 mL × g^-1, 6.89%; soybean: 82.07°C, 9.07 min, 0.80, 93.87 mL × g^-1, 15.81%; and peanut: 83.12°C, 8.11 min, 0.80, 168.70 mL × g^-1, 33.07%. Then, the optimization results for the five kinds of materials were synthesized by Origin 8.0 software, the fitting degree of the cubic model with the four extraction factors was the highest, the determination coefficients were 0.9984, 0.9991, 0.8953, and 0.9989, the residual sums of squares were 0.2888, 0.1587, 0.8265, and 0.1864, and the correlation coefficients are ideal. The stability and accuracy of the model were verified by the orthogonal experiment of UFA extraction from rice, and the correlation coefficient between the predicted value and the actual value of the orthogonal experiment was 0.9998. This study systematically collates the optimal parameters for microwave extraction of UFA content in different crops from the perspective of multimaterial and multiparameter, which can provide a large amount of detailed basic data for microwave extraction technology.

Nonenzymatic and rapid monitoring of uric acid levels is of great value for early diagnosis, prevention, and management of oxidative stress-associated diseases. However, fast, convenient, and low-cost uric acid detection remains challenging, especially in resource-limited settings. In this study, a novel and rapid biosensing approach was developed for the simultaneous visualization and quantification of uric acid levels by using the unique surface plasmon resonance and photothermal property of 4,5-diamino-2-thiouracil (DT)-capped gold nanoparticles (AuNPs). With the presence of uric acid, DT-capped AuNPs rapidly aggregated, and a visible color/photothermal change was used for uric acid quantification within 15 min. The limit of detection was determined to be 11.3 and 6.6 μM for the dual-mode biosensor, leveraging the unique structure of DT to optimize reaction kinetics. Moreover, the sensor exhibited excellent anti-interference capabilities and demonstrated potential for detecting a wide range of uric acid concentrations in complex samples, thereby reducing the need for extensive sample dilution and complex material synthesis procedures. Furthermore, validation against gold standard testing indicates that this biosensor could serve as a highly sensitive assay for quantifying uric acid levels in point-of-care applications, particularly in resource-limited settings.

Metformin (MET) is an oral antidiabetic drug widely used as the primary treatment for type 2 diabetes mellitus (T2DM). While various spectrophotometric assays exist for determining MET in pharmaceutical formulations, they often have limited throughput for quality control purposes. This study describes the validation of a 96-microwell plate spectrophotometer method using charge-transfer complexes (CTCs) with chloranilic acid (CLA) and 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) for the quality control and detected of MET. This reaction was carried out in 96-microwell plates, and the absorbance of the colored complexes of CLA and DDQ were measured at 530 nm and 460 nm, respectively, using an absorbance microplate reader. This study aims to identify and quantify the use of a 96-microwell plate spectrophotometer analytical technique for assessing complicated formulations. The method was successfully used for the quantification of MET in the tablet dosage form. The results showed good correlation coefficients (0.996 and 0.997) with CLA and DDQ, respectively. The present method showed high precision with RSD % not exceeding 2.17%. The accuracy of the method was obtained by recovery percentage, with percentage values less than ±5%. The Analytical Greenness Metric (AGREE) was used to evaluate greenness of the assays. The result show that the microwell assay method is greenness and suitable for handling large samples on a daily used with high throughput analysis. The use of the 96-microwell-plate method is superior to the existing method in terms of simplicity of the procedure, the low economic cost, and its consumption of low amounts of reagents and organic ethanol solvent, making it an environmentally friendly method. Therefore, these advantages make them suitable and rapid alternatives method to current methods for routine metformin analysis in quality control laboratories.

In the modern era, sol-gel plays a key role in the progress of a new generation of dispersive solid-phase microextractors (d-µ SPMEs) for the removal of organic and inorganic pollutants in complex matrices. Thus, the current study reports the use of sol-gel-functionalized polyurethane foams (PUFs) as a novel solid platform for complete extraction of chromium (VI) species from aqueous media. The planned protocol was based upon the complete extraction of the formed binary complex ion associates between the protonated ether and/or urethane groups of PUFs and chlorochromate anion [CrO₃Cl]^- _aq in aqueous HCl (≥1M) medium in addition to H-bonding and the electrostatic π-π interaction that resulted between the CrO₃Cl^- and the silanol group (Si/ZrO₂, Si-O-Zr) and siloxane (Si-O-Si) groups of the sol-gel. The impact of the analytical parameters (solution pH, natural mineral acids, shaking time, temperature, and chromium (VI) concentrations) was critically studied. At the optimal conditions, the uptake capacity of the established extractor (9.9 mg·g^-1) was in agreement with the Langmuir adsorption capacity (12.08 mg·g^-1) of the monolayer. The sorption data fitted well with the pseudo first-order kinetic model (R ² = 0.9961) with an overall rate constant (k ₁) of 0.081 min^-1 and an equilibrium capacity (q _e ) of 8.6 mg·g^-1, which is in a good agreement with the experimental value (9.9 mg·g^-1). The sorption of the oxyion [CrO₃Cl]^- _aq onto the solid sorbent is an endothermic and spontaneous process as reflected from the values of ΔH (6.99 kJ·mol^-1) and ΔG (-8.14 kJ·mol^-1 at 293 K), respectively. The ΔS value (15.13 kJ·mol^-1·K^-1) reflects that the [CrO₃Cl]^- _aq retention onto the sol-gel-treated PUFs sorbent proceeded in a more unplanned fashion. Sol-gel-treated PUFs sorbent-packed minicolumns were successfully used for the complete removal of trace levels of chromium (VI) species from water samples. Sorbed chromium (VI) species were recovered with NaOH (0.5 M) and analysed by spectrophotometry, which supports the utility of the sol-gel-treated PUFs as a low-cost solid extractor for water treatment.

An ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method was developed to determine the concentrations of Rhodojaponin II and Rhodojaponin III in rat plasma, and their pharmacokinetic profiles were investigated. A UPLC HSS T3 (2.1 mm × 50 mm, 1.8 μm) chromatographic column was employed at a temperature of 40°C. The mobile phase consisted of acetonitrile-0.1% formic acid in water, and a gradient elution method with an elution time of 6 min and flow rate of 0.4 mL/min was utilized for analysis purposes. Methodological investigations were conducted accordingly. The plasma concentrations of Rhodojaponin II and Rhodojaponin III exhibited excellent linearity within the range of 2 ng/mL-1250 ng/mL. Moreover, both intraday and interday precision were below 15%, while accuracy ranged from 88% to 115%. Additionally, matrix effect fell within the range of 90%-110%, and recoveries ranged from 78% to 87%. These results comply with relevant regulations for drug analysis in biological samples. Therefore, this method is deemed suitable for quantifying Rhodojaponin II and Rhodojaponin III levels in rats.

Introduction: In case of suspected acute recreational drug toxicity, immunoassays are commonly used as diagnostic tools. Although easy to handle, understanding of their limitations is necessary for a correct interpretation of the results. The aim of this project was to investigate residents' knowledge regarding drug screening immunoassays at a Swiss hospital group.

Methods: All residents of a large hospital group in Switzerland were invited by e-mail to participate in an anonymous survey. Following ten multiple choice questions on drug screening tests, the participants were also asked about their demographics, whether they used drug screening tests on a regular basis, and how confident they felt in their ability to interpret test results.

Results: The ten knowledge questions were answered by 110 of the 1026 residents (11%). Among the 108 participants with available demographics, 90% were 25-35 years old, 63% were female, and 70% were at least in their 4^th year of residency. The median score of correct answers was 4 out of 10 (range 0-7) and in 50% of the questions, the correct answer was the most frequently selected response. No significant differences in the knowledge scores were found based on the training, confidence level, or the frequency of drug tests used in daily work.

Conclusion: This survey revealed widespread knowledge gaps among residents regarding the interpretation of immunoassay-based drug test results. These findings can be used to implement educational measures on this topic and might provide a basis for targeted information on common pitfalls to be included in laboratory reports.