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Objective To establish a rapid prediction method of the antioxidant activity in aqueous extract solutions of Melastoma dodecandrum based on ultraviolet spectroscopy and partial least squares regression algorithm. Methods The DPPH free radical scavenging effect was used to characterize the antioxidant activity of aqueous extract solutions of Melastoma dodecandrum. The ultraviolet spectra of 190-600 nm were collected. The partial least squares regression model of antioxidant activity was established after optimizing the wavelength range and preprocessing method. The software was devised using Visual Basic as the integrated development environment to provide a convenient tool for the rapid determination of antioxidant activity. Results The optimal partial least squares regression model was established based on 200-290 nm as wavelength range and unit variance scaling as preprocessing method. The correlation coefficient of calibration, root mean square error of estimation, root mean square error of cross-validation was 0.887, 2.20% and 2.17%, respectively. The correlation coefficient of validation, root mean square error of prediction was 0.868, 2.08%. The average predicted recovery was 100.1±2.3%. With the predictive function in the software, the antioxidant activity of aqueous extract solution of Melastoma dodecandrum can be calculated automatically within 2 s after collecting the ultraviolet spectra. Conclusions This study provides a rapid method for the prediction of antioxidant activity in aqueous extract solutions of Melastoma dodecandrum.
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Objective To establish a method for content determination of total flavones and polysaccharides in Hedysari Radix in different producing areas in Gansu Province.Methods The contents of total flavones and polysaccharides in Hedysari Radix in different producing areas in Gansu Province were determined by ultraviolet spectroscopy with calycosin-7-glucoside and glucose as reference substance, and the wavelength was set at 260 nm and 484 nm.Results The contents were from 2.82 mg/g to 6.79 mg/g for total flavones and from 106.14 mg/g to 746.40 mg/g for total polysaccharides in Hedysari Radix in different producing areas in Gansu Province. The recoveries of total flavones and total polysaccharides were 97.96％ and 102.90％, respectively.Conclusion There was difference in contents of total flavones and polysaccharides of Hedysari Radix in different producing areas in Gansu Province, and the method of using ultraviolet spectroscopy is simple, reproducible, accurate and reliable, which can be preferably used as the method for content determination of total flavones and polysaccharides in Hedysari Radix.
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In this study, an analytical method based on ultraviolet spectroscopy was established for the rapid determination of nine components including isophorone, 4-methylene-isophorone, curcumenone, curcumenol, curdione, curzerenone, furanodienone, curcumol and germacrone in the first extraction process of Xingnaojing injection. 166 distillate samples of Gardeniae Fructus and Radix Curcumae were collected in the first extraction process of Xingnaojing injection. The ultraviolet spectra of these samples were collected, and the contents of the nine components in these samples were determined by high performance liquid chromatography. Least squares support vector machine and radial basis function artificial neural network were used to establish the multivariate calibration models between the ultraviolet spectra and the contents of the nine components. The results showed that the established ultraviolet spectrum analysis method can determine the contents of the nine components in the distillates accurately, with root mean square error of prediction of 0.068, 0.147, 0.215, 0.319, 1.01, 1.27, 0.764, 0.147, 0.610 mg•L⁻¹, respectively. This proposed method is a rapid, simple and low-cost tool for the monitoring and endpoint determination of the extraction process of Xingnaojing injection to reduce quality defects and variations.
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2,4,6-Trinitrotoluene (TNT) and its by-products dinitrotoluene (DNT) pose a significant threat to human health and other living organisms.However, the conventional analytical methods involved in bulky and expensive instruments are complicated and time-consuming, impeding quick and on-line determination.In this work, a facile yet effective strategy of utilizing UV-vis spectroscopy coupled with partial least squares (PLS) was proposed, through which TNT and two isomers of DNT (2,4-DNT and 2,6-DNT) in nature water could be rapidly and simultaneously determined without any pre-separation.Variable combination population analysis (VCPA) was utilized to select important feather variables and significantly improved the predictive performance of the PLS model.The calibration set contained 25 samples constructed by orthogonal array design (OAD).The predictive ability of the models was validated by an independent prediction set including 15 samples, achieving up to 0.99 of the determination coefficients (R2) for each of the analytes.The optimized models were successfully applied to determine the 3 ingredients in 8 environmental samples involving in tap, lake and two kinds of river water with the recovery values of great than 97%.Finally, the proposed method was further validated by high performance liquid chromatography method.UV-vis spectroscopy coupled with chemometrics may be used as simple and effective strategy with high potential in environmental monitoring.
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The study on natural product chemistry plays an important role in drug development, and the structure elucidation is one of the vital tasks in the natural product chemistry research. This paper summarized the application of UV, IR, MS, and NMR spectra in the structure elucidation of natural products with 123 papers cited. This article is one of the series of historical stories on natural product chemistry published in this journal, which are reviewed and summerized. The developing future is looked forward.
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In this work, the nickel-aluminum layered double hydroxide (Ni-Al LDH) with nitrate interlayer anion was synthesized and used as a solid phase extraction sorbent for the selective separation and pre-concentration of mefenamic acid prior to quantification by UV detection at λmax ? 286 nm. Extraction procedure is based on the adsorption of mefenamate anions on the Ni-Al(NO3? ) LDH and/or their exchange with LDH interlayer NO3? anions. The effects of several parameters such as cations and interlayer anions type in LDH structure, pH, sample flow rate, elution conditions, amount of nano-sorbent and co-existing ions on the extraction were investigated and optimized. Under the optimum conditions, the calibration graph was linear within the range of 2-1000 mg/L with a correlation coefficient of 0.9995. The limit of detection and relative standard deviation were 0.6 mg/L and 0.84% (30 mg/L, n ? 6), respectively. The presented method was successfully applied to determine of mefenamic acid in human serum and pharmaceutical wastewater samples.
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The objective of this study was to evaluate the utility of derivative spectrophotometric method for analysis of Diclofenac sodium (DIC) and Thiocolchicoside (THIO) in combination. Derivative spectrophotometry has allowed specific determination of Diclofenac sodium at 249 nm with negligible contribution by Thiocolchicoside. Similarly, Thiocolchicoside was determined at 246nm with negligible interference by Diclofenac sodium. The described method obeyed Beer’s law in the range of and 4-36μg/ml for DIC 2-10μg/ml for THIO. Validation parameters such as linearity, accuracy, precision, specificity, and LOD and LOQ values were performed. The percentage recovery was 99.52% for DIC and 99.32% for THIO. Intra and Interday precision %RSD values were <2. Thus from the results obtained it can be concluded that proposed method is simple, rapid and specific.
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A new, simple, specific, sensitive, rapid and economical procedure has been developed for determination of Nitroglycerin in its dosage form. The objective of this validation of an analytical procedure is to demonstrate that the drug Nitroglycerin is suitable for its intended purpose. The analytical method development recommends the quality, purity and specificity of the drug Nitroglycerin tablet form during the manufacturing process and hence the standard of the drug may not vary, which produce the desirable therapeutic effect. The method is based on the ultraviolet absorbance maxima of the above drug at 210nm. The drug obeyed Beer's law in the concentration range of 15μg/ml in methanol. The proposed methods were successfully applied for the determination of drug in commercial tablet preparations. The results of the analysis have been validated statistically and by recovery studies.
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A new, simple, specific, sensitive, rapid and economical procedure has been developed for determination of Nitroglycerin in its dosage form. The objective of this validation of an analytical procedure is to demonstrate that the drug Nitroglycerin is suitable for its intended purpose. The analytical method development recommends the quality, purity and specificity of the drug Nitroglycerin tablet form during the manufacturing process and hence the standard of the drug may not vary, which produce the desirable therapeutic effect. The method is based on the ultraviolet absorbance maxima of the above drug at 210nm. The drug obeyed Beer's law in the concentration range of 15μg/ml in methanol. The proposed methods were successfully applied for the determination of drug in commercial tablet preparations. The results of the analysis have been validated statistically and by recovery studies.