Analytical Sciences最新文献

Aqueous extracts of corn silk exhibit glycation-inhibitory activity. Lignin is the active component of these extracts. As corn silk is highly nutritious and has medicinal value, it can be used as a functional food and cosmetics. However, to achieve this goal, it is necessary to evaluate its quality. As lignin, which could be used as a marker compound for quality control, is a macromolecule, HPLC cannot be employed for the quality control of the aqueous extracts of corn silk. We here develop a method to evaluate the anti-glycation activity of the aqueous extracts of corn silk using attenuated total reflectance (ATR)-Fourier transform infrared (FTIR) spectroscopy along with multivariate statistical analysis. The inhibitory activity was evaluated using two multivariate calibrations: principal component regression (PCR) and partial least square regression (PLSR). The spectral areas of the PCR model were 633.5-880.3, 1191.8-1359.6, 1423.1-1492.6, and 2572.6-2974.7 cm^-1. Its coefficient of correlation (R² = 0.981) and root mean square error of cross validation (RMSECV = 2.356) were highly predictable. The spectral regions of 983.5-985.5 and 1021.1-1107.9 cm^-1 offered the best prediction models for the PLSR model. The R² value for the correlation between the actual values and the FTIR-predicted values was 0.994, while the corresponding RMSECV was 1.325%. Hence, FTIR spectroscopy along with multivariate calibration is a useful method for evaluating active corn silk aqueous extracts.

Nateglinide is an oral meglitinide that treats diabetes. Nateglinide was determined in several commercial formulations using chromatographic and spectrophotometric methods in published research. Quality-by-design approach was applied to develop the in-house nateglinide-loaded Solid Dispersion Adsorbate (SDA) for improving bioavailability and solubility. To determine nanogram-level nateglinide concentration for the in-house developed nateglinide-SDA pharmacokinetics required time-consuming and expensive hyphenated analytical techniques such as LC-MS or UPLC-MS. Hence, a sensitive spectrofluorophotometric method was developed to estimate nateglinide using NBD-Cl (7-chloro-4-nitrobenzoxadiazole) as the fluorophore. Microwave-aided chemical derivatization of nateglinide with NBD-Cl sped up sample analysis. Chemical reaction solvents were eco-friendly to safeguard aquatic life and environment. The chemical process was optimized by quality by design approach using screening design and response surface modelling. The fluorescence intensity of nateglinide was found to be linear over the concentration range of 20-250 ng/mL with a correlation coefficient of 0.9978. The limits of detection and quantification were found to be 10 and 20 ng/mL respectively. Precision and robustness investigations of the spectrofluorimetric method showed less than 2% relative standard deviations. Nateglinide-SDA drug-release study and pharmacokinetics were performed using the sensitive spectrofluorophotometric method. The in-house developed nateglinide-SDA released 95% of the drug in 30 min time duration. In-house-developed nateglinide-SDA has 1.5 times the oral bioavailability of commercial formulations due to in-vivo absorption. The published analytical methods were compared to the enhanced-spectrofluorophotometric method for user-friendliness, efficiency, cost-of-analysis, and environmental friendliness. The proposed sensitive-spectrofluorophotometric method was found to be robust, rapid, eco-friendly, cost-effective, and simple for the estimation of nateglinide.

Calibrations in LA-ICP-MS are typically very time-consuming and complex, as they need to be matched to the samples being measured and sectioned on a microtome. Alternatively, gelatin can be in droplet form or as a section, which is a more recent development. In this study, we report on investigations where hot multi-element gelatin solutions are placed in a linear fashion on microscopic slides to conduct comparative statistical observations between doped tissue homogenates from the liver and lung. The tissue homogenates served as both samples (complete ablation) and calibration standards (partial ablation) for verification purposes. We explored the effects of different laser fluences (0.50-1.50 J/cm²), gelatin contents (0.3-20.0%) and section thicknesses (10-30 µm). To do this, we evaluated the samples by calculating median and mean values over the entire section with and without removal of elementary spikes (de-spiking). A reduction in distribution was achieved with averaging. The data was normalized using ¹³C as an internal standard. In these experiments and under these measurement conditions, it was observed that the selected laser fluences, gelatin contents, and section thicknesses did not visibly affect the results, making them comparable. Each sample could be assessed with each gelatin calibration, allowing for determination of expected reference values. Despite interruptions in the measurement operation, due to the high number of measurements, where samples and calibrations could not be analyzed in one measurement run, no negative effects of stopping and starting the LA-ICP-MS were observed.

In this study, we employed femtosecond Raman-induced Kerr effect spectroscopy to analyze the concentration-dependent intermolecular dynamics in positively or negatively charged aromatics and their neutral analogous aromatics (imidazolium hydrochloride (ImHCl), imidazole (Im), sodium triazolide (NaTr), and triazole (Tr)) in aqueous solutions at 293 K. We also measured their liquid properties, such as density, viscosity, and surface tension, at 293 K, and compared them with their dynamic properties. Furthermore, we performed the quantum chemistry calculations of the target aromatics and some clusters to elucidate their optimized structures, interaction energies, charge populations, and Raman-active normal modes. We characterized the Kerr transients over 2 ps using a triexponential function. The results revealed that the aqueous solutions' intermediate and slow relaxation time constants were linearly proportional to the viscosities. The slopes of the time constants to the viscosity of the aqueous ImHCl solutions were steeper than those of the aqueous Im solutions, whereas the slopes of the aqueous NaTr solutions were milder than those of the aqueous Tr solutions. These findings indicated that the charge of the aromatics in the aqueous solutions affected the coupling parameter between the solute and solvent in the orientational dynamics with different ways. The first moment (M₁) of the low-frequency band (< 200 cm^-1), coming from the intermolecular vibrations, in the difference spectra between the aqueous aromatic solutions and neat water shifted to the high-frequency region as the concentration increased. The M₁ slope to the concentration for the aqueous ImHCl solutions was steeper than that for the aqueous Im solutions. Conversely, the concentration dependence of M₁ for the aqueous NaTr solutions was similar to that for the aqueous Tr solutions. We used the local structures of the target aromatics based on the quantum chemistry calculations to rationally clarify their concentration-dependent intermolecular dynamics in the aqueous solutions.