共查询到20条相似文献,搜索用时 0 毫秒
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Emerson Vidal de Aquino 《Talanta》2007,71(3):1288-1293
A monosegmented volumetric Karl Fischer titrator is described to mechanize the determination of water content in organic solvents. The system is based on the flow-batch characteristics of the monosegmented analysis concept and employs biamperometry to monitor the progress of the titration. The system shows accuracy and precision that are highly independent of the flow rate, does not require calibration, and is carried out in a closed system capable of minimizing contact of the sample and reagents with ambient moisture. Sample volumes in the range of 40-300 μL are employed, depending on the water concentration. An automatic dilution is provided to deal with concentrated samples. The consumption of Karl Fischer reagent depends on the water content of the sample but is not larger than 100 μL. The system was evaluated for determination of water in ethanol and methanol in the range 0.02-0.5% (w/w). The average relative precision estimated in that range (9-3%) is comparable to that obtained with a larger volume commercial system and no significant difference was observed between the results obtained for the two systems at the 95% confidence level. A complete titration can be performed in less than 5 min employing the proposed system. 相似文献
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Donald W. Rogers Jae -Ha Kim Shantilal C. Patel Richard A. Wurm 《Mikrochimica acta》1985,87(5-6):297-306
Summary
A Microcomputer-Controlled Microcalorimeter Calibration Circuit
3. Enthalpies of Solution of Linear and Cyclic Alkanes in Glacial Acetic Acid
The molar enthalpy of solution ofn-alkanes and cycloalkanes has been studied in an isoperibol calorimeter at 25.0 °C. Reasoning from a purely volumetric effect of intrusion of solute molecules into an associated solvent, we might expect compact cycloalkane molecules to disturb the solvent structure less than linear alkanes and to have a smaller exothermic enthalpy of solution than then-alkanes. That is not the case, evidently, as the cyclic compounds mix with aH
s that is exothermic in the same degree as their linear counterparts. These results are discussed in terms of a model in which each alkane molecule occupies a cavity in the structured solvent that is large with respect to itself. Enthalpy of solution of saturated alkanes in glacial acetic acid does not depend on the geometry of the alkane for the two homologous series studied thus far. 相似文献
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A simple photo-electric apparatus is desscribed for the automatic titration of small amounts of carbon dioxide The apparatus is based on automatic titrant shut-off controlled by a photoresistor and is used for the non-aqueous titration proposed by Blomet al. (pyridine/monoethanolamine medium, sodium methanolate titrant). 相似文献
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A new type of automatic recording titrator has been developed. The titrant is added intermittently and the titration curve is recorded stepwise, potential changes being registered in the intervals between deliveries of titrant. The increments of titrant and the intervals can be pre-set, but give the best results if controlled automatically during the titration. The end-point and the volume of titrant consumed are read from the recorded titration curve. 相似文献
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A computer-controlled automatic titrator incorporating a weight burette is described. The titration vessel is mounted on the pan of a zero-displacement digital balance which records the weight of added sample as well as the weight of titrant added during the titration. 相似文献
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A microprocessor control system is reported for automated multiple flow injection analysis. The control system consists of an IMSAI-8048 microprocessor, some associated electronic interfacing and a control computer command language. The system can be programmed to control any of three versions of automated multiple flow injection analysers. This control system is relatively inexpensive and is suitable for use by inexperienced personnel. 相似文献
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A method of controlling an automatic titrator by means of a microcomputer is described. Experimental titration data have been analysed by the use of approximative or rational spline functions. 相似文献
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Heinrich Hillig Hendrik Küper Wolfgang Riepe Hans Peter Ritter 《Analytica chimica acta》1979,112(2):123-132
Automation of a mass spectrometer—computer system makes it possible to process up to 30 samples without attention after sample loading. An automatic sample changer introduces the samples successively into the ion source by means of a direct inlet probe. A process control unit determines the operation sequence. Computer programs are available for the hardware support, system supervision and evaluation of the spectrometer signals. The most essential precondition for automation — automatic evaporation of the sample material by electronic control of the total ion current — is confirmed to be satisfactory. The system operates routinely overnight in an industrial laboratory, so that day work can be devoted to difficult analytical problems. The cost of routine analyses is halved. 相似文献
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J.A.C. Broekaert W.-D. Hagenah K. Laqua F. Leis D. Stüwer 《Spectrochimica Acta Part B: Atomic Spectroscopy》1986,41(12):1357-1365
Concept and operation of a microcomputer-controlled dual-channel monochromator system are described. A 0.9-m Czerny-Turner monochromator is equipped with two stepping motors: one for wavelength adjustment by rotating the grating, the other for driving a quartz refractor plate as a means for flexible background measurement. Instrument control as well as data acquisition and processing are performed by a 16 bit Intel 8088 based microcomputer system. The whole system is operated via a console keyboard with a simple dialogue. Main topics of the software are: setting operational parameters; automatic wavelength access using a peak searching routine with a screening window down to 0.05 nm; simple line intensity measurement; line and background measurement alternatively in one channel and simultaneously in two channels with a wavelength distance up to ± 0.05 nm using the quartz refractor plate, and stepwise intensity measurement (“profiling”) with an increment down to 0.0007 nm. Intensity values are acquired with a 12 bit resolution. Results are printed on a console typewriter. The performance of the instrument is demonstrated by applications in inductively coupled plasma atomic emission spectroscopy (ICP-AES) with steady and transient signals. 相似文献
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M. Attas J. D. Chen E. A. Hildebrandt 《Journal of Radioanalytical and Nuclear Chemistry》1987,109(1):55-68
A fully automated neutron activation analysis (NAA) facility has been constructed at the Whiteshell Nuclear Research Establishment. This high-capacity facility has been designed for use with a wide variety of neutron sources, including Canada's SLOWPOKE II and MAPLE research reactors. Its pneumatic transfer system is driven by a Square-D Model 500 programmable controller, linked in turn to a Nuclear Data ND6700 computer/spectrometer. Custom software for data entry and system control has been combined with Nuclear Data software for gamma-spectrum acquisition and processing to create a flexible, easy-to-use facility for NAA. Its design and performance are discussed. 相似文献
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Higginson M. Palmer K. King J. Dawkins B. Huggins T. Ingman L. Taylor F. Xu N. Kaye P. 《Journal of Radioanalytical and Nuclear Chemistry》2019,320(3):689-698
Journal of Radioanalytical and Nuclear Chemistry - Novel methods for sample preparation by adapting an automated chromatography system to radiochemical analysis for analysis of trace impurities is... 相似文献
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N. N. Papadopoulos G. E. Hatzakis A. C. Salevris N. F. Tsagas 《Journal of Radioanalytical and Nuclear Chemistry》1997,215(1):103-110
A combination of special techniques has been developed for optimization of experimental conditions in order to improve the analytical capability, to facilitate automation and to broaden the applicability of instrumental neutron activation analysis. The techniques used are: (1) compensation for the rapid radioactive decay of short-lived nuclides with the increase of the counting efficiency by automatic source movement to the detector during the counting period, to minimize count rate variations and to prolong the counting period, (2) repeated cyclic and cumulative activation to improve the counting statistics, (3) instrumental correction of counting losses at high and varying count rates by a loss-free counting system and (4) differentiation of the reactor neutron spectrum to enhance the counts from the nuclides of interest by reducing matrix interferences. By optimized combination and automation of these techniques significant improvement of the capability of instrumental neutron activation analysis can be achieved. 相似文献
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Summary The potential of different chromatographic systems for automated, on-line analysis of amphetamine in biological fluids is
illustrated. The various systems integrate analyte purification and enrichment, separation, derivatization in different derivatization
modes witho-phthaldialdehyde (OPA) and N-acetyl-L-cysteine (NAC), and fluorimetric detection. The reliability of the systems has been
tested by analysing urine and plasma samples containing amphetamine in the 0.1–20.0 μg mL−1 range. Pre, on and post-column derivatization strategies are compared in terms of their instrumental requirements, selectivity,
sensitivity, linearity and reproducibility. 相似文献
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