Baileytoft0666
The implementation of near-infrared spectroscopy as an analytical method for the quantification of major wine parameters is limited due to the aqueous nature of wines. Water molecules contribute to a poor signal-to-noise ratio and to suppress important groups' vibrations frequencies, preventing the quantification of most chemical compounds present. This paper proposes an alternative approach for the quantification of major wine indicators based on near infrared spectroscopy using lyophilized wine samples. A diversity of wine samples, including red, white and rosé, were lyophilized and analyzed by NIR spectroscopy. The parameters quantified were alcoholic degree, volumic mass, total dry extract, total sugars, total acidity, volatile acidity, pH, free sulfur dioxide and total sulfur dioxide. Calibrations using partial least squares (PLS) regression were performed against the results obtained by reference methods. Spectra collected within 10,000 to 4000 cm-1 range were randomly divided in two sets one for the optimization of the PLS models and the remaining for external testing. The PLS models obtained were able to accurately quantify total sugars, pH, volumic mass and total dry extract with a range-error-ratio above 10. The quantification of the remaining parameters yielded unsatisfactory results. This methodology proved to be an interesting alternative for the quantification of major wine quality descriptors by circumventing the interference of water bands. Further studies exploring different lyophilization conditions and additional wine chemical compounds present at low concentrations are needed. WP1066 solubility dmso A glycidyl methacrylate-based monolith was modified with imidazolium-based ionic liquid (IL) to be used as stationary phase for solid-phase extraction (SPE). The host monolithic support was prepared by in-situ UV polymerization in spin column format. Two approaches were developed to incorporate the IL into the polymeric monolithic matrix generation of IL onto the surface monolith, and copolymerization by addition of the IL to the polymerization mixture, which gave the best results. The resulting sorbent materials were morphologically characterized and used for the isolation of five β-blockers from human urine samples. All SPE steps were accomplished by centrifugation, which reduces significantly costs and time in sample treatment. Under optimal conditions, β-blockers were quantitatively retained in the modified monolith at pH 12, and desorbed with a water-methanol mixture, to be subsequently determined via HPLC with UV detection. The limits of detection ranged between 1.4 and 40 μg L-1, and the reproducibility among extraction units (expressed as relative standard deviation) was below 8.2%. The novel phase was successfully applied to the extraction of propranolol in urine samples with recoveries above 90%. In this work, a rapid and sensitive ratiometric fluorescence sensing method for the detection of ascorbic acid (AA) and ascorbate oxidase (AA-Ox) was developed. MPA capped quaternary CuInZnS QDs with fluorescence emission wavelength of 580 nm was synthesized by hydrothermal synthesis. Thiamine (VB1) can be oxidized by KMnO4 to yield thiochrome (oxVB1) with a fluorescence emission peak at 459 nm. So positively charged thiamine and negatively charged MPA modified CuInZnS QDs can form a ratiometric fluorescence system via electrostatic interaction. The presence of AA will consume KMnO4, which can inhibit the oxidization of thiamine, accompanied with a decrease of the fluorescence intensity at 459 nm, while the fluorescence of CuInZnS QDs at 580 nm remains the same when AA is present, so the fluorescence intensity ratio (I459/I580) decreased. When AA was oxidized by AA-Ox, KMnO4 could not be reduced by AA, which caused the fluorescence intensity of thiochrome at 459 nm restored, and the fluorescence intensity ratio (I459/I580) increased again. Therefore, AA and AA-Ox can be monitored by detecting the fluorescence intensities ratio at 459 and 580 nm. Moreover, the developed detection system for AA and AA-Ox displayed a good linear relationship from 0.05 to 0.25 μmol L-1 and 0.1-5 mU·mL-1, and the detection limit are 0.011 μmol L-1 and 0.078 mU·mL-1, respectively. The proposed method was applied to the determination of AA-Ox in human serum samples with satisfactory results. Potential degradation products (DPs), even in small concentrations, can cause changes in pharmacological and toxicological properties of a drug with a significant impact on product quality and safety. Thus, their stability and understanding of possible degradation mechanisms have a significant importance. Although liquid chromatography is the conventional technique used for forced degradation studies with excellent accuracy and reproducibility, the main disadvantages of the technique are being expensive and time-consuming. As a powerful technique, surface-enhanced Raman scattering (SERS) can be an alternative with its high sensitivity, easy sample preparation and low cost. In this study, the degradation of both tofacitinib (TOF), a Janus kinase inhibitor, and methotrexate (MTX), an inhibitor of tetrahydrofolate dehydrogenase, are studied using SERS under hydrolytic, oxidative and thermal conditions using mesoporous silica coated silver nanoparticles (Si@AgNPs) as SERS substrates. The study demonstrated that the degradation of the tested drugs using Si@AgNPs as SERS substrates could be monitored through the spectral changes on SERS spectra of drugs under several degradation conditions. Development of stretchable potentiometric ion sensors has the observable potential for wearable devices to continuously monitoring of electrolytes in body fluids. However, the mechanical mismatch between soft elastomeric substrate and ion-selective electrode components greatly hinders sensor's fabrication and its stretching stability for long-term use. Here, we propose a new strategy to construct a potentiometric ion sensor on a surface strain redistributed elastic fiber (SSRE-fiber) with both high stretchability and high sensing stability. The SSRE-fiber is designed with a unique unilateral bead structure, which significantly changes its surface strain distribution during deformation. Benefit from this platform, the active sensing materials with high Young's modulus fabricated on the unilateral bead region can keep unchanged during stretching (0-200%). Thus, the as-prepared potentiometric sensors (ion-selective electrode and polymer/inorganic salt membrane-coated reference electrode) can perform with stable functions ignoring the stretching of the fiber.