Search results for "Preparation"
showing 10 items of 939 documents
Current trends in affinity-based monoliths in microextraction approaches: A review
2019
Abstract This article reviews the research contributions along the past five years concerning to monolithic materials for the development of affinity-based sorbents in the field of microextraction techniques. The first part of this paper includes an introduction regarding monolithic affinity media and information of different binding agents (such as immunoglobulin-binding proteins, enzymes, lectins, antibodies, aptamers, dyes and immobilized metal ions and nanoparticles, among others) that can act as affinity ligands. Then, the preparation of monoliths and ligand immobilization strategies as well as the different available formats (syringes, pipette tips, spin columns, capillaries, disks an…
Photoinduced ultrafast dynamics of Ru(dcbpy)2(NCS)2-sensitized nanocrystalline TiO2 films:The influence of sample preparation and experimental condit…
2004
In most of the previous ultrafast electron injection studies of Ru(dcbpy)2(NCS)2-sensitized nanocrystalline TiO2 films, experimental conditions and sample preparation have been different from study to study and no studies of how the differences affect the observed dynamics have been reported. In the present paper, we have investigated the influence of such modifications. Pump photon density, environment of the sensitized film (solvent and air), and parameters of the film preparation (crystallinity and quality of the film) were varied in a systematic way and the obtained dynamics were compared to that of a well-defined reference sample: Ru(dcbpy)2(NCS)2−TiO2 in acetonitrile. In some cases, …
Effect of Experimental and Sample Factors on Dehydration Kinetics of Mildronate Dihydrate: Mechanism of Dehydration and Determination of Kinetic Para…
2014
The dehydration kinetics of mildronate dihydrate [3-(1,1,1-trimethylhydrazin-1-ium-2-yl)propionate dihydrate] was analyzed in isothermal and nonisothermal modes. The particle size, sample preparation and storage, sample weight, nitrogen flow rate, relative humidity, and sample history were varied in order to evaluate the effect of these factors and to more accurately interpret the data obtained from such analysis. It was determined that comparable kinetic parameters can be obtained in both isothermal and nonisothermal mode. However, dehydration activation energy values obtained in nonisothermal mode showed variation with conversion degree because of different rate-limiting step energy at hi…
The ways to the trace level analysis in infrared spectroscopy
2020
The future of infrared (IR) spectroscopy as an analytical technique is assured due to its versatility and its numerous advantages; such as the possibility to obtain molecular specific information for virtually any sample in any state with no treatment or minimal sample preparation. However, spectroscopists are not satisfied with relegating IR spectroscopy just to major and minor component analysis and have been looking at analysis at the trace level too. This review is the recognition of the brilliant research performed during the past two decades and the advances achieved in this area, which have made possible the analysis of contaminants at parts per billion (ppb) levels by IR in differen…
An overview of the analytical methods for the determination of organic ultraviolet filters in biological fluids and tissues.
2012
Organic UV filters are chemical compounds added to cosmetic sunscreen products in order to protect users from UV solar radiation. The need of broad-spectrum protection to avoid the deleterious effects of solar radiation has triggered a trend in the cosmetic market of including these compounds not only in those exclusively designed for sun protection but also in all types of cosmetic products. Different studies have shown that organic UV filters can be absorbed through the skin after topical application, further metabolized in the body and eventually excreted or bioaccumulated. These percutaneous absorption processes may result in various adverse health effects, such as genotoxicity caused b…
Artificial neural network for quantitative determination of total protein in yogurt by infrared spectrometry
2009
Abstract A method has been introduced for quantitative determination of protein content in yogurt samples based on the characteristic absorbance of protein in 1800–1500 cm− 1 spectral region by mid-FTIR spectroscopy and chemometrics. Successive Projection Algorithm (SPA) wavelength selection procedure, coupled with feed forward Back-Propagation Artificial Neural Network (BP-ANN) model was the benefited chemometric technique. Relative Error of Prediction (REP) in BP-ANN and SPA-BP-ANN methods for training set was 7.25 and 3.70 respectively. Considering the complexity of the sample, the ANN model was found to be reliable, while the proposed method is rapid and simple, without any sample prepa…
Combining land preparation and vegetation restoration for optimal soil eco-hydrological services in the Loess Plateau, China
2019
Abstract In semiarid terrestrial ecosystems, optimized eco-rehabilitation strategies, such as land preparations and planting vegetation, are keys to achieve a successful ecological restoration. Land preparations and vegetation are supposed to have the coupled and respective impacts on soil ecosystem services, which are still unclear now. In this study, eighteen experimental plots with six different combinations and repetitions of land preparations and vegetation were built in the Chinese Loess Plateau in 2014 and soil moisture storages (SMS), soil carbon stocks (SCS) and other soil nutrient stocks were calculated at 0–100 cm, also the effects of land preparations and planting vegetation on …
A review on the phytopharmacological studies of the genus Polygala
2020
Abstract Ethnopharmacological relevance The genus Polygala, the most representative genus of the Polygalaceae family, comprises more than 600 species from all over the world of which around 40 are distributed in China, some of them, being used in the Traditional Chinese Medicine system. Aim of the review We intend to discuss the current knowledge about the traditional uses, and the newest phytochemical and pharmacological achievements with tentative elucidation of the mechanism of action on the genus Polygala covering the period 2013–2019 to provide a scientific support to the traditional uses, and to critically analyze the reported studies to obtain new insights for further researches. Mat…
An in-tube SPME device for the selective determination of chlorophyll a in aquatic systems.
2010
We report a new device for the estimation of the content of chlorophyll a pigment in water samples as an indicator of water quality. The extraction of the pigment from water was also optimized. 10 mL of water was filtered through a nylon filter (45m pore size and 13 mm of diameter), after the chlorophylls were dissolved by immersing the filter in 1 mL of a low non-hazardous solvent as ethanol. An in-valve in-tube SPME device coupled to capillary liquid chromatography with diode array detection was designed. A capillary column of 70 cm in length (0.32 mm i.d. coated with 5% diphenyl–95% polydimethylsiloxane, 3m coating thickness) was used as the loop of the injection valve for preconcentrati…
Multi-residue determination of organic micro-pollutants in river sediment by stir-disc solid phase extraction based on oxidized buckypaper
2020
This paper describes a procedure for the isolation of 20 organic micro-pollutants among pesticides, drugs, recreational drugs, flame retardants from river sediments. After a solid-liquid extraction with a methanol:water (50:50, v/v) solution, the supernatant was diluted with water and cleaned up by stir-disc solid-phase extraction (SPE). The disc was made of buckypaper, a self-supporting entangled assembly of carbon nanotubes, which was used as a highly porous, two-sided, sorbent membrane. In the preliminary activation step, the membrane was oxidised for 2-hours with nitric acid to extend its extraction capability also to more polar compounds. All extracts were analysed by ultra-high-perfor…