Computerized instruments

The technician needs only 5 minutes per batch for evaluation, including graphics and tables because the computerized instrument and the integrator do the rest. 

A computerized laboratory can utilize a software package called a laboratory information and management system (LIMS) to carry out or control all of these requirements provided that computerized instrumentation, computer terminals, printers and plotters, disk drives etc. are linked together in a local... 

For any process the ratio between the current of the reverse peak and that of the forward peak, /pr//pf, is particularly important. This current ratio is the parameter which allows one to judge the chemical reversibility of an electrode reaction. In fact, when such a ratio is equal to 1, the electrogenerated species Red is stable (at least on the cyclic voltammetric timescale). The /pr//pf ratio is easily calculated in computerized instrumentation or must be determined graphically in... 

Qualitative chemistry is an area of chemistry concerned with identifying substances. In Activity 9.1 you will perform a qualitative analysis to detect the presence of certain ions that, in turn, may reveal an art forgery. The ions could come from paints that were not available at the time of the artwork. In this qualitative analysis, metal ions (cations) and nonmetal ions (anions) are reacted with solvents and with each other. Then the cations and anions present are identified by the products produced. In addition, flame tests and pH determinations are used to identify ions. Qualitative analysis is an engaging opportunity for you to develop experience with chemical change and review solubility principles. Nowadays, however, most of the time a chemist analyzes a substance to detect ion content using quantitative analytical computerized instruments. 

Other methods have been developed for the removal of oxygen (particularly from flowing streams).These include the use of electrochemical or chemical (zinc) scrubbers, nitrogen-activated nebulizers, and chemical reduction (by addition of sodium sulfite or ascorbic acid). Alternately, it may be useful to employ voltammetric methods that are less prone to oxygen interference. The background-correction capability of modern (computerized) instruments is also effective for work in the presence of dissolved oxygen. 

Under the term smooth curves we understand any curves obtained by the computerized instruments that are represented as intensities sampled in equidistant intervals. In such curves not only the positions of maxima (peaks), but also the shape of the curve between them is important. A typical example for such objects in chemistry are infrared (IR) spectra of compounds, represented with N intensities or chromatograms sampled in N equidistant time intervals. All such measurements are of course written as measurement vectors X (eq. 5.1). 

In many respects, the held of chemometrics is the child of statistics, computers, and the information age. Rapid technological advances, especially in the area of computerized instruments for analytical chemistry, have enabled and necessitated phenomenal growth in the held of chemometrics over the past 30 years. For most of this period, developments have focused on multivariate methods. Since the world around us is inherently multivariate, it makes sense to treat multiple measurements simultaneously in any data analysis procedure. For example, when we measure the ultraviolet (UV) absorbance of a solution, it is easy to measure its entire spectrum... 

Chilamkurti, R. N., Rhodes, C. T., and Schwartz, J. B. (1982), Some studies on compression properties of tablet matrices using a computerized instrumented press, Drug Dev. Ind. Pharm., 8, 63-86. 

Indeed, it is entirely possible to obtain a competitive edge by possessing a method or technique that better predicts true commercial catalyst performance. As catalyst testing matures and computerized instrumentation improves, the "art" of catalyst manufacturing is slowly yielding to science. 

There is hardly any laboratory without at least a computerized instrument. A good example is the Chromatography Data System (CDS). Before, these instruments create graphs on a paper, and we cut them out and weigh them to determine the component. Today every chromatograph is connected to a CDS, which makes all the calculations according to how we set it up. 

The mass spectrometer is a highly sophisticated and computerized instrument, which basically consists of five parts sample introduction, ionization, mass analysis, ion detection, and data handhng. In principle, hquid chromatography is just one of the possible analyte techniques, or the mass spectrometer just another detector for LC. However, on-line chromatography-MS systems offer additional value, especially in terms of selectivity. 

Use your Web browser to connect to http //chemistry.brookscole.com/skoogfac/. From the Chapter Resources menu, choose Web Works. Locate the Chapter 12 Section, and click on the link to the articles on classical analysis by C. M. Beck. In these articles, which were originally published in the scientific literature, Beck makes a strong case for the revival of classical analysis. What is Beck s definition of classical analysis Why does Beck maintain that classical analysis should be cultivated in this age of automated, computerized instrumentation What solution does he propose for the problem of dwindling numbers of qualified classical analysts List three reasons why, in Beck s view, a supply of classical analysts must be maintained. 

Crouch, S.R. Atkinson, TV. The Amazing Evolution of Computerized Instruments, Anal. Chem. 72(17), 597A-603A (2000). 

For trace analysis of cations, the technique that introduces the minimum value of uncertainty is anodic stripping voltammetry. The reason is that the concentration and determination steps take place on the same electrode. The lower value of uncertainty is also a function of the use in the technique of a fully computerized instrument. In this case, the computerization of the instrument is of prime importance for decreasing the uncertainty because it assures a high reproducibility of the parameter characteristics for anodic stripping voltammetry. 

Whether we use our senses or a million dollar computerized instrument, the "bottom line" is the same We are measuring a change in one or more chemical or physical properties in an effort to understand the changes taking place in a chemical system. 

An interesting contribution to data processing Is the work by Bond [39], In which the performances of different variants of the voltammetrlc technique (seml-lntergral, seml-differentlal, direct current linear sweep, direct current derivative linear sweep and pulse and related techniques) were compared with the aid of computerized Instrumentation. 

Because ICP spectra for many elements arc so rich in lines, spectral interferences are always possible. To avoid this type of error requires knowledge of all of the components likely to he present in the sample and a careful study of the information in the reference works listed in note 16. The software for modern computerized instruments has powerful routines for wavelength atid concentration calibration, spectral analysis, and deconvolution of overlappittg lines. These features coupled with itttcgraled databases of spectral lines make spotting and correcting for interferences an integral part of the analytical process. 

Most personal errors can be minimized by care and self-discipline. Thus, most scientists develop the habit ofsystematically double-checking in.strument readings, notebook entries, and calculations. Robots, automated sv stenis, computerized data collection, and computerized instrument control have the potential of minimizing or eliminating most personal-type systematic errors. 

Havelock Ellis remarked that What we call progress is the exchange of one nuisance for another nuisance. The advent of computerized instruments has certainly made routine a number of difficult spectroscopic measurements. Unfortunately, the sophistication of the procedures now available can result in erroneous results or interpretations if they are not used with caution. A classic example is the use of curve-resolving techniques. There is always a suspicion that a good fit between an observed spectral profile and a number of bands can be obtained providing that a sufficient number of the latter are included in the analysis. Clearly, in such cases a prior knowledge of the number of bands and their frequency would significantly increase our confidence in the results. 

Interacting with the computerized Instrument to obtain and Interpret data ... 

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