Search results for "analytical"

Room temperature acid sonication ICP-MS multielemental analysis of milk

2005

Abstract Room temperature acid sonication of milk samples is proposed as a fast alternative methodology for the determination of the total content of 45 elements (Li, Al, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Rb, Sr, Y, Mo, Ag, Cd, In, Sn, U, Sb, Te, Cs, Ba, Hg, Pb, Bi, Th, La, Ce, Pr, Nd, Sm, Eu, Gd, Dy, Ho, Er, Tm, Yb, Lu, Hf and Ta) in milk by inductively coupled plasma mass spectrometry (ICP-MS). The aforementioned procedure involves a 10 min sample pre-treatment. Measurements were made in quantitative and semiquantitative (Totalquant ® ) modes of analysis using Rh as internal standard and Be, Ge, Tb and Re for internal calibration of the equipment in the semiquantitative mode. The…

Dependence of plasma pH on oxygen saturation

1969

Abstract The influence of haemoglobin oxygenation on the pH value of the blood plasma of healthy adolescents was investigated at 38°C by varying the parameters CO2 pressure, Hb concentration and buffer bases. A total of 5000 measurements gave the following results: 1. 1. The pHs difference between oxygenated and deoxygenated blood increases with diminishing CO2 pressure and with increasing Hb concentration. There is a linear relation between the pHs changes and the O2 saturation of the haemoglobin. 2. 2. Quantitatively these relationships can be expressed by the following equation: δpHs = (8 − pH ox − log 0.03 Pco 2 ) · [Hb] 225 · (100 − So 2 100 where ΔpHs is the pHs difference between par…

Electronic properties of Co2MnSi thin films studied by hard x-ray photoelectron spectroscopy

2009

This work reports on the electronic properties of thin films of the Heusler compound Co2MnSi studied by means of hard x-ray photoelectron spectroscopy (HAXPES). The results of photoelectron spectroscopy from multilayered thin films excited by photons of 2?8?keV are presented. The measurements were performed on (substrate/buffer layer/Co2MnSi(z)/capping layer) multilayers with a thickness z ranging from 0 to 50?nm. It is shown that high energy spectroscopy is a valuable tool for non-destructive depth profiling. The experimentally determined values of the inelastic electron mean free path in Co2MnSi increase from about 19.5 to 67?? on increasing the kinetic energy from about 1.9 to 6.8?keV. T…

Optical properties of silver halide fibres: ageing effects

1996

The relation between the structure of fibres extruded from mixed silver halides and their IR optical losses and luminescence properties is studied. The recently established ageing effect of the considerable growth of mean grain size of the fibre's polycrystalline structure (typically from 20 to 1000 nm in two years) is correlated with IR and luminescence measurements. IR spectra measured in the interval show growth of the concentrations of molecular impurities. The luminescence measurements are used for the characterization of the fibre's structure ordering. The luminescence decay kinetics is analysed theoretically in terms of the diffusion-controlled recombination of spatially well-correla…

Thermoelectric properties of CoTiSb based compounds

2009

Several CoTiSb based compounds were synthesized and investigated on their thermoelectric properties. The aim was to improve the thermoelectric properties of CoTiSb by the systematic substitution of atoms or the introduction of additional Co into the vacant sublattice. The solid solutions Co1+xTiSb, Co1?yCuyTiSb and CoTiSb1?zBiz were synthesized. X-ray diffraction was used to investigate the crystal structure. The resistivity, the Seebeck coefficient and the thermal conductivity were determined for all compounds in the temperature range from 2 to 400?K. The highest figure of merit for each solid solution is presented. We were able to improve the figure of merit by a factor of approximately s…

Global-Local model for guided wave scattering problems with application to defect characterization in built-up composite structures

2020

Abstract Predicting scattering of elastic guided waves in multi-layered solid plates with geometrical and/or material discontinuities is of great interest to many fields, including ultrasonic-based Non-Destructive Testing (NDT) and health monitoring of critical structural components (SHM). The problem is complicated by the multimode and dispersive behaviour of the guided waves. This paper describes a unified Global-Local (GL) approach that is computationally efficient in cases that can be very complex in terms of geometry and/or material properties. One example of this is a composite built-up structure. The proposed GL procedure discretizes the “local” region with the scattering discontinui…

Development of a sensitive method for the determination of acrylamide in coffee using high-performance liquid chromatography coupled to a hybrid quad…

2015

The emerging trend towards high-resolution mass spectrometry (MS) alternatives was evaluated by the application of Orbitrap MS for the determination of acrylamide in coffee samples. The high resolving power of the Orbitrap MS provided the high selectivity and sensitivity that enabled quantitative analysis of acrylamide in complex matrices, such as coffee. Several sample preparation methods and scanning modes of the MS (full MS, t-SIM, t-MS2) were assessed in order to optimise parameters of the analytical method. The final procedure involved the extraction of acrylamide with acetonitrile, solid-phase extraction with dispersive primary secondary amine (PSA) and amino columns, and the detectio…

Cast multibilayer films from polymerizable lipids

1987

Preparation and characterization of octadecyl acrylate monoliths for capillary electrochromatography by photochemical, thermal, and chemical initiati…

2013

Monolithic stationary phases based on octadecyl acrylate for CEC using different initiating systems (UV irradiation, thermal, and chemical initiation) in the presence of lauroyl peroxide as initiator were synthesized. For each initiation mode, the influence of the porogenic solvent composition on both the morphological and electrochromatographic properties of the resulting monoliths was investigated. Under optimal conditions, excellent efficiencies for the photochemically and chemically polymerized monoliths (minimum plate heights of 6.9–10.7 and 6.5–12.6 μm, respectively) were achieved. Thermally initiated columns gave lower efficiency values, permeabilities, and longer analysis times comp…

Chemical initiation for butyl and lauryl acrylate monolithic columns for CEC.

2009

Butyl acrylate (BA)- and lauryl acrylate (LA)-based monolithic stationary phases for CEC were synthesized, using a redox system as initiator of polymerization. BA monoliths were initiated with ammonium peroxodisulfate, whereas LA columns were obtained with lauroyl peroxide as initiator. In both cases, TEMED was used to activate the process. The influence of porogenic solvent composition on both morphological and electrochromatographic properties of the resulting monoliths was investigated. Excellent efficiencies (minimum plate heights of 4.2-6.3 microm for BA columns and 2.6-5.3 microm for LA stationary phases, for a PAHs mixture) were achieved. The capability of separation of both types of…