Computer-aided instrumentation

GC-Computer System Nowadays, a large number of data-processing-computer-aided instruments for the automatic calculation of various peak parameters, for instance relative retention, composition, peak areas etc., can be conveniently coupled with GC-systems. A commercially available fairly sophisticated computer system of such type are available abundantly that may be capable of undertaking load upto 100 gas-chromatographs with ample data-storage facilities. In fact, the installation such as multi GC-systems in the routine analysis in oil-refineries and bulk pharmaceutical industries, and chemical based industries have tremendously cut-down their operating cost of analysis to a bare minimum. 

In most design offices Computer Aided Design (CAD) methods are now used to produce the drawings required for all the aspects of a project flow-sheets, piping and instrumentation, mechanical and civil work. 

The excellent, high-resolution y- and X-ray spectra which can be obtained from semiconductor detectors make the detectors very important in modern instruments. A typical spectrum is shown in Figure 10.11(b) which may be compared with the much broader peaks from a scintillation detector (Figure 10.11(a)). The spectra are not immune from the problem of Compton scattering (p. 461) but a good quality modem detector will have a photopeak to Compton peak ratio of 50 1 or better. Computer-aided spectrum analysis also serves to reduce the interference from the Compton effect. 

FT IR instruments can have very high resolution (<0.001 cm-1). Moreover since the data undergo ana-log-to-digital conversion, IR results are easily manipulated Results of several scans are combined to average out random absorption artifacts, and excellent spectra from very small samples can be obtained. An FT IR unit can therefore be used in conjunction with HPLC or GC. As with any computer-aided spectrometer, spectra of pure samples or solvents (stored in the computer) can be subtracted from mixtures. Flexibility in spectral printout is also available for example, spectra linear in either wavenumber or wavelength can be obtained from the same data set. 

The electrical resistance of non-aqueous electrolytic solutions is often much higher than that of aqueous ones, and so polarographic and voltammetric measurements in non-aqueous solutions should be made with a three-electrode device. A computer-aided three-electrode instrument, equipped with a circuit for iR-drop compensa-... 

The grade determines whether the mica can be used in high technology elecironic instruments, e.g.. computer-aided tomography (CATl scan, or in low technology devices, e.g.. a toaster. Many types of insulators, as well as the base for electronic circuits, are formed from the high quality sheets of mica by a punch pressing operation. 

The field of particle size distribution analysis has experienced a renaissance over the past five years and is now a rapidly growing and lively area of scientific and technological activity. This revitalization has been driven by advances in electronics and computer technology in conjunction with the market pull for particle size distribution analysis methods that cover a wide dynamic particle size range and have improved resolution. These technological advances are embodied in computer-aided, user-friendly, reliable, and cost-effective instrumentation. Three activities characterize this renaissance. 

The second activity is characterized by the revitalization of older instrumental methods such as gravitational and centrifugal sedimentation methods. Redesign, modernization with advanced electronics, and user-friendly, computer-aided analysis have extended the instrument product life cycle. A good example is disc centrifuge photosedimentometry (DCP), the subject of three chapters in this volume. 

Miettinen, J.K. (Ed.), Computer-Aided Techniques for the Verification of Chemical Disarmament. E.l. Verification Database. Methodology and Instrumentation for Sampling and Analysis in the Verification of Chemical Disarmament, The Ministry for Foreign Affairs of Finland, Helsinki, 1988. 

In the modern age of medicinal chemistry, QSAR modeling remains one of the most important instruments of computer-aided drug design. Skillful application of various methodologies discussed in this chapter will afford validated QSAR models, which should continue to enrich and facilitate the experimental process of drug discovery and development. 

For the reader interested in staying up to date with TLC, the Journal of Planar Chromatography, first published in 1988, is a good source of information. Two hooks are also suggested for the reader who wishes to study planar chromatography in greater depth. The first one discusses planar chromatography, from the basics to instrumentation and computer-aided methods [15]. The second book concentrates on TLC and describes sample preparation, sample application, phases selection, visualisation, quantitation, special techniques and combined methods such as TLC-GC, TLC-IR and TLC-MS. It also contains a useful list of suppliers for TLC instrumentation and equipment [16]. 

The radioactive-tracer technique was perfected for. fluidized-bed application through the development of a computer-aided particle-tracking facility (CAPTF) (Lin, Chen, and Chao, 1985 Moslemian, 1987 Sun, 1989). Considerable effort was expended to develop the efficient photoncounting instrumentation and automated data reduction and processing schemes. In Section 9.2, the principle of radiation detection and a theoretical model of the CAPTF is presented. The instrumentation of the CAPTF and the data reduction schemes are described in Section 9.3. Sample results obtained by the CAPTF are presented in Sections 9.4 and 9.5, and a conclusion is presented in Section 9.6. 

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