Search results for "Chemical analysis."
showing 10 items of 308 documents
Biodegradable tablets having a matrix of low molecular weight poly-L-lactic acid and poly-D,L-lactic acid.
1990
Biodegradable Homo- and Copolymers of lactic and glycolic acids have been used for manufacture of microparticles and matrix implants1,5). To ensure sufficient hydrolytic matrix stability lactic acids of high and medium degree of polymerization have been used. The manufacture of poly lactic acid tablets with an average molecular weight of 25000 and 6000 was reported recently, after finishing the following study2). Bioabbaubare Gerusttabletten aus niedermolekularer poly-L-Milchsaure und poly-D,L-Milchsaure
Highly selective and sensitive chromo-fluorogenic detection of the Tetryl explosive using functional silica nanoparticles
2011
Silica nanoparticles containing polyamines and thiol groups have been used as probes for the selective detection of Tetryl. © 2011 The Royal Society of Chemistry.
Aroma behaviour during steam cooking within a potato starch-based model matrix.
2012
To help understand the organoleptic qualities of steam cooked foods, the kinetics of aroma release during cooking in a potato starch based model matrix was studied. Behaviour of components having a major impact in potato flavour were studied using solid phase micro extraction-gas chromatography (SPME-GC). Evolution of microstructure of potato starch model-matrix during steam cooking process was analyzed using environmental scanning electron microscopy (ESEM). Both aroma compounds that are naturally present in starch matrix and those that were added were analyzed. Both the aroma compounds naturally presented and those added had different behaviour depending on their physico-chemical properti…
New background correction approach based on polynomial regressions for on-line liquid chromatography-Fourier transform infrared spectrometry.
2008
Abstract In the present study a new approach for the chemometric background correction in on-line gradient LC–FTIR is introduced. For this purpose, the spectral changes of the elution mixture during gradient elution were analyzed applying 2D correlation spectroscopy. The fundamentals of the new background correction algorithm, based on polynomial fits calculated from a reference spectra matrix (Polyfit-RSM method) are explained. The Polyfit-RSM approach was applied on blank gradient runs as well as on LC–FTIR data obtained from the injection of a soft drink sample using acetonitrile:water as eluent. Results found were critically assessed and compared to those obtained by two previous backgr…
Protein Thermal Denaturation and Matrix Glass Transition in Different Protein−Trehalose−Water Systems
2011
Biopreservation by saccharides is a widely studied issue due to its scientific and technological importance; in particular, ternary amorphous protein-saccharide-water systems are extensively exploited to model the characteristics of the in vivo biopreservation process. We present here a differential scanning calorimetry (DSC) study on amorphous trehalose-water systems with embedded different proteins (myoglobin, lysozyme, BSA, hemoglobin), which differ for charge, surface, and volume properties. In our study, the protein/trehalose molar ratio is kept constant at 1/40, while the water/sugar molar ratio is varied between 2 and 300; results are compared with those obtained for binary trehalose…
Metaproteomic analysis of atmospheric aerosol samples.
2016
Metaproteomic analysis of air particulate matter provides information about the abundance and properties of bioaerosols in the atmosphere and their influence on climate and public health. We developed and applied efficient methods for the extraction and analysis of proteins from glass fiber filter samples of total, coarse, and fine particulate matter. Size exclusion chromatography was applied to remove matrix components, and sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) was applied for protein fractionation according to molecular size, followed by in-gel digestion and LC-MS/MS analysis of peptides using a hybrid Quadrupole-Orbitrap MS. Maxquant software and the Swiss-…
Analysis of mycotoxins in barley using ultra high liquid chromatography high resolution mass spectrometry: comparison of efficiency and efficacy of d…
2012
The effectiveness of four extraction methods (modified QuEChERS, matrix solid-phase dispersion (MSPD), solid-liquid extraction (SLE) and solid-phase extraction (SPE) clean-up) were evaluated for simultaneous determination of 32 mycotoxins produced by the genus Fusarium, Claviceps, Aspergillus, Penicillium and Alternaria in barley by ultra high pressure liquid chromatography coupled to ultra-high resolution mass spectrometry (UHPLC-Orbitrap(®) MS). The efficiency and efficacy of extraction methods were evaluated and compared in number of extracted mycotoxins and obtained recoveries. From the one point of view, QuEChERS procedure was fast and easy, as well as it was able to successfully extra…
Control of matrix interferences by the multiple linear regression model in the determination of arsenic, antimony and tin in lead pellets by inductiv…
2002
A multiple linear regression technique was used to evaluate the matrix interferences in the determination of hydride-forming elements in lead shotgun pellets by inductively coupled plasma atomic emission spectrometry. The determination of arsenic, antimony, and tin in SRM C2416 (Bullet Lead) by ICP-AES failed to obtain the certified concentrations at the 95% level of confidence using the t-test. However, it proved possible, by using the multiple linear regression technique, to correct the concentrations of all three elements to a statistically acceptable level. This method of correction is based on the multiple regression line obtained from the analysis of 19 synthetic mixtures of matrix el…
Electrochemical characterization of mangrove sediments: A proposal of new proxies for organic matter oxidation
2019
Abstract The voltammetric response of microparticulate deposits resulting from solvent evaporation of ethanolic extracts of mangrove sediments in contact with aqueous acetate buffer is hereby described. Dated sediment cores sampled from the Peruvian mangrove system (“Manglares de Tumbes” National Sanctuary) presented voltammetric responses dominated by oxidative signals of organic components that exhibit significant variations depending on the depth. Voltammetric data allowed for the definition of electrochemical indexes representative of the electrochemically oxidable organic matter fraction. These electrochemical indexes were fEAOM (for the total amount of organic matter being electrochem…
An effective negative pressure cavitation-microwave assisted extraction for determination of phenolic compounds in P. calliantha H. Andr.
2013
A novel negative pressure and microwave assisted extraction technique (NMAE) was first proposed and applied for extraction of phenolic compounds from pyrola. [C₄MIM]BF₄ aqueous solution was selected as extraction solvent. Optimal extraction conditions were microwave power 700 W, negative pressure -0.07 MPa, temperature 40 °C, liquid-solid ratio 20 : 1, ionic liquid (IL) concentration 0.5 M, extraction time 15 min. The predominance of NMAE was investigated by comparing with microwave-assisted extraction (MAE) and negative pressure cavitation extraction (NPCE) using a first-order kinetics equation. The C∞ values of the target compounds by NMAE were from 0.406 to 5.977 mg g⁻¹ higher than these…