Search results for "Chemical analysis"
showing 10 items of 324 documents
The determination of certain major and minor elements in geological samples by inductively coupled plasma atomic emission spectrometry. Some interfer…
2000
Direct ICP-AES measurements of the digested geological standard reference material samples yielded the wrong information about their composition. The differences between certified and measured concentrations of the samples were due to the complicated sample matrix. The measured concentrations can be successfully corrected by using a multiple linear regression technique. The correction is based on the multiple regression line calculated from the analytical results at synthetic mixtures of matrix elements, where concentrations varied on five levels. There were no significant (P = 0.05) differences between certified and measured concentrations in standard reference materials after the correcti…
Vitamin D deficiency predicts cognitive decline in older men and women: The Pro.V.A. Study
2014
Objective: To test the hypothesis that hypovitaminosis D is associated with a higher risk of cognitive decline over a 4.4-year follow-up in a large sample of older adults. Methods: This research was part of the Progetto Veneto Anziani (Pro.V.A.), an Italian populationbased cohort study of 1,927 elderly subjects. Serum 25-hydroxyvitamin D (25OHD) levels were measured at the baseline. Global cognitive function was measured with the Mini-Mental State Examination (MMSE); scores lower than 24 were indicative of cognitive dysfunction, and a decline of 3 or more points on the MMSE over the follow-up was considered as clinically significant. Analyses were adjusted for relevant confounders, includin…
Evaluation of multifunctional liposomes in human blood serum by light scattering.
2014
To overcome the limited functionality of "stealth" lipids based on linear poly(ethylene glycol) (PEG) chains, hyperbranched polyether-based lipids that bear multiple hydroxyl groups for further chemical modification may be a suitable replacement. This study focuses on the development and characterization of "stealth" liposomes modified with a novel hyperbranched polyglycerol lipid (cholesterol-PEG30-hbPG23). An emphasis was placed on the stability of these liposomes in comparison to those containing a linear PEG derivative (cholesterol-PEG44) directly in human blood serum, characterized via dynamic light scattering (DLS). Polymer lipid contents were varied between 0 and 30 mol %, resulting …
Extraction of β-blockers from urine with a polymeric monolith modified with 1-allyl-3-methylimidazolium chloride in spin column format
2020
Abstract 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 reduce…
Quantitative determination of trichothecenes in breadsticks by gas chromatography-triple quadrupole tandem mass spectrometry.
2014
Breadsticks are pencil-sized sticks of dry bread widely consumed as a pre-meal appetiser. They are basically wheat-based snacks, which makes them a good matrix to evaluate mycotoxin contamination, since wheat is very susceptible to fungal attack. In this sense, the fast, selective and sensitive gas chromatography-triple quadrupole tandem mass spectrometry (GCQqQ- MS/MS) method proposed here allows simultaneous determination of deoxynivalenol (DON), 3-acetyldeoxynivalenol, fusarenon-X, diacetoxyscirpenol, nivalenol, neosolaniol, HT-2 and T-2 toxin in breadsticks after QuEChERS extraction and clean-up. The performance of the method was assessed with respect to European Commission Regulations …
Bioaccessibility of tocopherols, carotenoids, and ascorbic acid from milk- and soy-based fruit beverages: Influence of food matrix and processing
2012
A study was made of the effect of high-pressure processing (HPP) and thermal treatment (TT) on plant bioactive compounds (tocopherols, carotenoids, and ascorbic acid) in 12 fruit juice-milk beverages and of how the food matrix [whole milk (JW), skimmed milk (JS), and soy milk (JSy)] modulates their bioaccessibility (%). HPP (400 MPa/40 °C/5 min) produced a significant decrease in carotenoid and ascorbic acid bioaccessibility in all three beverages and maintained the bioaccessibility of tocopherols in JW and JS while decreasing it in JSy. TT (90 °C/30 s) produced a significant decrease in tocopherol and carotenoid bioaccessibility in all three beverages and increased the bioaccessibility of …
Micellar liquid Chromatographic determination of diuretics by diazotization and coupling with the Bratton-Marshall reagent
1997
Abstract A Chromatographic procedure that uses micellar mobile phases of sodium dodecyl sulphate (SDS) and propanol at pH 3 is reported for the determination, in urine samples, of thiazide diuretics (althiazide, bendroflumethiazide, chlorothiazide, hydrochlorothiazide, hydroflumethiazide, and trichloromethiazide), and other diuretics having a sulphonamide substituent in the benzene ring. Precolumn derivatization with sodium nitrite and N -(1-naphthyl)ethylenediamine, to form the coloured azo dyes of the hydrolyzed diuretics, decreased the polarity of the compounds and, consequently, their retention in the micellar eluents, and permitted detection in the visible region, eliminating thus the …
Optical chemosensors and reagents to detect explosives
2012
[EN] This critical review is focused on examples reported from 1947 to 2010 related to the design of chromo-fluorogenic chemosensors and reagents for explosives (141 references). © 2012 The Royal Society of Chemistry.
Haptens, bioconjugates, and antibodies for penthiopyrad immunosensing
2014
4 pages, 1 table, 2 figures.
Improved Photocatalytic Activity of Polysiloxane TiO2 Composites by Thermally Induced Nanoparticle Bulk Clustering and Dye Adsorption
2021
Fine control of nanoparticle clustering within polymeric matrices can be tuned to enhance the physicochemical properties of the resulting composites, which are governed by the interplay of nanoparticle surface segregation and bulk clustering. To this aim, out-of-equilibrium strategies can be leveraged to program the multiscale organization of such systems. Here, we present experimental results indicating that bulk assembly of highly photoactive clusters of titanium dioxide nanoparticles within an in situ synthesized polysiloxane matrix can be thermally tuned. Remarkably, the controlled nanoparticle clustering results in improved degradation photocatalytic performances of the material under …