Direct analysis of Al2O3 powders by total reflection X-ray fluorescence spectrometry
A direct analysis procedure for the determination of trace impurities of Ca, V, Cr, Mn, Fe, Ni, Cu, Zn and Ga in Al2O3 ceramic powders by total reflection X-ray fluorescence spectrometry (TXRF) is described. The powders were analysed in the form of slurries containing 1–10 mg mL−1 of powder. The use of the procedure in the case of powders with differing grain size and for different slurry concentrations was investigated. Three different quantification possibilities were compared, namely the use of Al as a matrix component, the use of Fe as a trace element contained in the sample or of Co added in concentrations of 200 μg g−1 as internal standard. The homogeneity of elemental distributions in sample layers deposited on the TXRF quartz carriers by evaporating 5 μL of the 10 mg mL−1 slurries was studied by scanning the 4- to 5-mm-diameter spots of two samples by synchrotron radiation TXRF at Hasylab. For powders with differing graininess but mainly finer than about a few 10 μm, no systematic influence of the grain size on the accuracy of the determinations of Ca, V, Fe, Ni, Cu and Zn could be observed. The measurement precision, however, seemed to be limited by inhomogeneous distributions of the trace elements in the samples as testified by the synchrotron radiation TXRF scans. Detection limits of the developed TXRF procedure for Ca, V, Cr, Mn, Fe, Ni, Cu, Zn and Ga were found to be in the 0.3–7 μg g−1 range and were shown to increase slightly with the grain size of the samples. Quantification using Al (matrix) as internal standard led to systematically higher values out of the accuracy required, whereas the other two approaches in all cases led to reliable results.
Innovation in atomic spectrometric methods for chemical analysis
The importance of chemical-physical methods of analysis for a wide variety of applications in different fields of relevance to technological innovation, risk assessment in public and environmental health and sustainability is shown up at the hand of necessary developments in the methods of analysis. At the example of plasma atomic spectrometry and new developments in x-ray spectrometry for the determination of elemental and species concentrations it is shown up how herewith challenging analytical tasks in the fields mentioned before can be solved. Examples for material analysis, among others at the hand of novel ceramic powders such as precursors for high-temperature superconductors, water analysis and determinations in food as well as the determinations of hazardous species of heavy metals in waste water will be presented. Important lines of development toward the improvement of the power of detection, the minimization of efforts for sample pretreatment and the increase of the cost performance ratio also from the point of the instrumentation, as a result of the use of cheaper sources than the inductively coupled plasmas such as microwave plasmas, miniaturized devices and glow discharges, will be treated. Also progress in the calibration for the case of total reflection X-ray spectrometry by the use of picodroplets will be discussed.
An intelligent control system for ventilators.
This study reports on a ventilator system that consists of several intelligent modules for controlling ventilator operation. These modules are software programs in two controllers. One controller is a personal computer used for diagnoses, determining settings and checking the effects of settings. The other controller is a single-chip microprocessor in a ventilator that controls the ventilator's settings in accordance with the computer settings. After setting up the system, an artificial lung model simulating a patient's lung is used to test the system. The result of test run indicated that it always responds to a patient's lung condition in a stable manner. Thus, the proposed system with its intelligent modules may assist clinicians in caring for patients and managing ventilator operation.