Multi-residue screening of veterinary drugs in egg,fish and meat using high-resolution liquid chromatography accurate mass time-of-flight mass spectrometry

The last 2 years multi-compound methods are gaining ground as screening methods. In this study a high-resolution liquid chromatography combined with time-of-flight mass spectrometry (HRLC–ToF-MS) is tested for the screening of about 100 veterinary drugs in three matrices, meat, fish and egg. While the results are satisfactory for 70–90% of the veterinary drugs, a more efficient sample preparation or extract purification is required for quantitative analysis of all analytes in more difficult matrices like egg. The average mass measurement error of the ToF-MS for the veterinary drugs spiked at concentrations ranging from 4 to 400 μg/kg, is 3.0 ppm (median 2.5 ppm) with little difference between the three matrices, but slightly decreases with increasing concentration. The SigmaFit value, a new feature for isotope pattern matching, also decreases with increasing concentration and, in addition, shows an increase with increasing matrix complexity. While the average SigmaFit value is 0.04, the median is 0.01 indicating some high individual deviations. As with the mass measurement error, the highest deviations are found in those regions of the chromatogram where most compounds elute from the column, be it analytes or matrix compounds. The median repeatability of the method ranges from 8% to 15%, decreasing with increasing concentration, while the median reproducibility ranges from 15% to 20% with little difference between matrices and concentrations. The median accuracy is in between 70% and 100% with a few compounds showing higher values due to matrix interference. The squared regression coefficient is >0.99 for 92% of the compounds showing a good overall linearity for most compounds. The detection capability, CCβ, is within 2 times the associated validation level for >90% of the compounds studied. By changing a few conditions in the analyses protocol and analysing a number of blank samples, it was determined that the method is robust as well as specific. Finally, an alternative validation strategy is proposed and tested for screening methods. While the results calculated for repeatability, within-lab reproducibility and CCβ show a good comparison for the matrices meat and fish, and a reasonable comparison for the matrix egg, only 27 analyses are required to obtain these results versus 63 analysis in the traditional, 2002/657/EC, approach. This alternative is suggested as a cost-effective validation procedure for screening methods.     

Observation of E.M. radiation at ƒpe and its harmonics emitted by a turbulent plasma

Electromagnetic radiation emitted by a turbulent plasma is measured. The frequency spectrum shows maxima at harmonics of the plasma frequency.     

Behaviour of plasmalogens during high-performance liquid chromatography on a silica column with a mobile phase containing phosphoric acid

Silica high-performance liquid chromatographic separation of phospho- and sphingolipids of biological origin using a mobile phase containing phosphoric acid leads to gradual hydrolysis of plasmalogens during their passage through the column. The resulting 2-acyl lyso analogues give rise to peaks that tail in the direction of the parent intact plasmalogen. Tailing can be prevented by previous complete acid hydrolysis of plasmalogens. Direct high-performance liquid chromatographic profiling of phospholipids, their plasmalogens (as 2-acyl lyso analogues) and sphingolipids is probably the method of choice for the diagnosis of patients with deficient plasmalogen biosynthesis caused by peroxisomal abnormalities.     

Monitoring of impending myocardial damage after pleuropneumonectomy and intraoperative photodynamic therapy for malignant pleural mesothelioma using biochemical markers

In five patients who were treated for malignant pleural mesothelioma (MPM) with pleuropneumonectomy and intraoperative photodynamic therapy (IPDT), impending myocardial damage was monitored using ECG, the classical biochemical markers (creatine kinase [CK], total activity; CKMB, mass; and myoglobin), and the new cardiac markers troponin I (cTnI) and troponin T (cTnT). In the peroperative and postoperative period all classical markers were elevated, in contrast to cTnI and cTnT, because of the concomitant skeletal muscle damage. Sequential electrocardiogram monitoring showed no signs of myocardial damage. From this study in patients with MPM treated with pleuropneumonectomy and IPDT it can be concluded that measurement of cTnI and cTnT for the detection of myocardial damage is more suitable than measurement of the classical markers.     

Corona Above Water Reactor for Systematic Study of Aqueous Phenol Degradation

A small batch reactor is developed to study the removal of phenol from a thin layer of water by creating pulsed corona discharges above the water. Pulses of up to 40 kV are applied with a duration of ~50 ns and an energy of ~60 mJ. In this CAW (Corona Above Water) reactor an ozone yield of upto 90 g/kWh is obtained in ambient air. The phenol degradation is 48 g/kWh, using a 1 mM initial concentration in demineralized water. The degradation yield increases to almost 100 g/kWh by adding to the water either H₂O₂ or Fe₂SO₄ or NaOH. The first two additions are considered to increase to amount of OH radicals. In the case of NaOH addition it is observed that much more ozone dissolves in the water. The addition of the OH scavenger t-butanol shows that in most cases the main oxidation route of phenol in the CAW reactor is direct ozone attack.     

On the evaluation of some differential formulations for the pom-pom constitutive model

In recent years, progress has been made in modelling long chain branched polymers by the introduction of the so-called pom-pom model. Initially developed by McLeish and Larson (1998), the model has undergone several improvements or alterations, leading to the development of new formulations. Some of these formulations however suffer from certain mathematical defects. The purpose of the present paper is to review some of the formulations of the pom-pom constitutive model, and to investigate their possible mathematical defects. Next, an alternative formulation is proposed, which does not appear to exhibit mathematical defects, and we explore its modelling performance by comparing the predictions with experiments in non-trivial rheometric flows of an LDPE melt. The selected rheometric flows are the double step strain, as well as the large amplitude oscillatory shear experiments. For LAOS experiments, the comparison involves the use of Fourier-transform analysis.     

Détermination de la réactivité d'un réacteur fortement réfléchi

Sans résuméSubside N^o 4353 du Fonds national suisse de la recherche scientifique.     

First measurement of electron-cyclotron emission spectra from PLT

The frequency spectrum of electron-cyclotron radiation from the PLT-device has been measured by observing in a vertical direction. The line profiles of 2ω_ce and 3ω_ce are broad and show a central intensity dip. An interpretation is given in terms of reflections on the vacuum vessel and self-absorption.     

Combined Effects of Pulsed Discharge Removal of NO,SO2, and NH3 from Flue Gas

Experiments have been performed using pulsed high-voltage discharges with the aim of removing NO and SO ₂ from flue gas obtained from a methane burner. It is found that the NO conversion is strongly increased by the addition of SO ₂ or NH ₃ . When both gases are added simultaneously the increase almost disappears. The synergetic effect can be maintained, as is shown, when NH ₃ is introduced much later than SO ₂ . The SO ₂ removal is already 70% upon stoichiometric addition of NH ₃ , but the electric discharge improves this to >95% and reduces the NH ₃ leak to a few ppm. This increase is probably related to aerosol production by the pulsed discharge which enhances the ammonium salt production. A so-called history effect is observed, i.e., the removal of NO and SO ₂ depends on the time that is taken to reach the required energization. It appears that the discharge has to create favorable conditions for the cleaning process. Using the synergetic and history effects the best cleaning result, at initial concentrations of 300 ppm, is 80% NO removal and 95% SO ₂ removal with 3 ppm NH ₃ leak. In this case the energy cost is 13 eV/NO (or a yield of 90 g NO and 200 g SO ₂ per kWh). Possibilities for further improvement are indicated.