Analytical instruments, development

Figure 4.13. Cross-sectional diagram of a diffusion tube (courtesy Analytical Instrument Development).

Dr. Frederick J. Debbrecht, Analytical Instrument Development, Avondale, Pa. 

A book dealing with instruments that have been developed by a community connected to both science and industry (termed the research-technology community ) has chapters on Fourier-transform spectrometers and liquid scintillation counters.309,310 Precision scientific instruments were produced by specialist manufacturers the growth of the instruments industry in Britain and France between 1870 and 1939 has been the subject of a book.311 Of the analytical instruments developed in the 20th century, the most widely used has been the pH meter, and its invention and marketing by A. O. Beckman has been described.312... 

One could argue that, although it is true that the analytical instruments developed during the 1940s and 1950s were more cost efficient, required less skiU to operate, and promoted standardization of data collection and presentation, this does not mean that they are more objective that is a distinct question. Consequently, there is nothing to learn about the concept of objectivity from noting its—accidental—connection with these other values. 

STRATEGY AND PROGRAM TOWARD DEVELOPING CUTTING-EDGE ANALYTICAL INSTRUMENTS AND DEVICES A NEW INITIATIVE BY JAPANESE GOVERNMENT... 

Analytical instruments play an increasingly important role in modern analytical chemistry. The trend is not limited in chemistry but in all phases of natural science and technology, as one easily can watch in rapid progresses in molecular biology, nano-materials technology, and the related bio-medical reseai ch. Instiaimental developments can now even be a determining factor in the advancement of science itself. 

The classical polarizing light microscope as developed 150 years ago is still the most versatile, least expensive analytical instrument in the hands of an experienced microscopist. Its limitations in terms of resolving power, depth of field, and contrast have been reduced in the last decade, in which we have witnessed a revolution in its evolution. Video microscopy has increased contrast electronically, and thereby revealed structures never before seen. With computer enhancement, unheard of resolutions are possible. There are daily developments in the X-ray, holographic, acoustic, confocal laser scanning, and scanning tunneling micro-... 

The general utility of the light microscope is also recognized by its incorporation into so many other kinds of analytical instrumentation. Continued development of new composites and materials, together with continued trends in microminiaturization make the simple, classical polarized-light microscope the instrument of choice for any initial analytical duty. 

Recent advances in accelerator technology have reduced the cost and size of an RBS instrument to equal to or less than many other analytical instruments, and the development of dedicated RBS systems has resulted in increasing application of the technique, especially in industry, to areas of materials science, chemistry, geology, and biology, and also in the realm of particle physics. However, due to its historical segregation into physics rather than analytical chemistry, RBS still is not as readily available as some other techniques and is often overlooked as an analytical tool. 

The contemporary chromatograph used for analytical purposes is a very complex instrument that may operate at pressures up to 10,000 p.s.i.and provide flow rates that range from a few microliters per minute to 10 or 20 ml/minute. Solutes can be detected easily at concentration levels as low as lxlO-9 g/ml and a complete analysis can be carried out on a few micrograms of sample in a few minutes. The range of liquid chromatographs that is available extends from the relatively simple and inexpensive instrument, suitable for the majority of routine analyses, to the very elaborate and expensive machines that are more appropriate for analytical method development. 

The need to develop new materials for electrophoretic analysis and macromolecular separations prompted by the needs of the human genome project and the rapidly advancing fields associated with biotechnology, advances in the development of new analytical instrumentation—especially capillary electrophoresis, and practical limitations of the media currently used for gel electrophoresis [73]... 

Therefore, chemists should concentrate on developing and applying appropriate analytical instrumentation and other newly-emerging technologies to isolate, separate and identify the complex mixtures obtained from the crude plant samples. Once all chemicals are correctly identified, their identity must be confirmed by synthesis and comparison of biological activity with the natural compounds. 

Lynch [316] has recently critically reviewed the future development in analytical instrumental SCF technology. Modern instruments include manual and automated extractors that can handle large sample volumes (lOOmL for manual SFE and lOmL for automated SFE). From an experimental point of view, in using SFE attention should be paid to contamination from the seals of the SCF extractor. 

SFE instrument development has greatly been stimulated by the desire of the Environmental Protection Agency (EPA) to replace many of their traditional liquid-solvent extraction methods by SFE with carbon dioxide. In the regulatory environment, EPA and FDA approved SFE and SFC applications are now becoming available. Yet, further development requires interlaboratory validation of methods. Several reviews describe analytical SFE applied to polymer additives [89,92,324]. 

Published evidence highlights the efficacy of SFE. However, the method is highly matrix and analyte dependent and must be optimised for each combination of material and analyte. Interaction between analyte and matrix is often difficult to predict and optimisation of the extraction procedure is not simple. Understanding of the processes that occur during SFE has lagged behind instrumental developments. The results obtained from SFE are highly dependent on the operational parameters used during the extraction (Table 3.19). 

If one wishes to predict the future of additive analysis in polymers, it is relevant to consider the prospects of further evolution of polymeric and additive materials the influence of legislation and environment instrumental developments and currently unsolved problems. It then becomes clear that additive analysis stands a fair chance remaining in use for some time, certainly in a strongly competitive environment, which will require improved product design specifications, quality assurance and research for new applications. As ideal production environments are rare, customer complaints will also require continuous attention. Government regulations are another reason for continuous analytical efforts. 

Table 10.22 Basis for selection of analytical technique Table 10.23 Future instrumental developments...

The use of GC-MS in polymer/additive analysis is now well established. Various GC-based polymer/additive protocols have been developed, embracing HTGC-MS, GC-HRMS and fast GC-MS with a wide variety of front-end devices (SHS, DHS, TD, DSI, LD, Py, SPE, SPME, PTV, etc.). Ionisation modes employed are mainly El, Cl (for gases) and ICPI (for liquid and solid samples). Useful instrumental developments are noticed for TD-GC-MS. GC-SMB-MS is a fast analytical tool as opposed to fast chromatography only [104]. GC-ToFMS is now about to take off. GC-REMPI-MS represents a 3D analytical technique based on compound-selective parameters of retention time, resonance ionisation wavelength and molecular mass [105]. 

The continually increasing sensitivity of analytical instruments makes it possible to probe smaller samples. For smaller volumes, surface properties become more important. Surface analysis is a rather new and rapidly developing field. Analytical difficulties increase with the degree of heterogeneity, from homogeneous to surface treated, coated, layered, continuously varying composition to totally heterogeneous. 

Any attempt to give an up-to-date account of physical methods of chemical analysis of materials must suffer from the problem of aiming at a moving target. In the chapters which follow I have attempted to illustrate the selected techniques with examples taken from the recent literature of the subject. However I am aware that there is constant instrument development and improvement, so that what follows is at best only a description of analytical equipment that is commercially available at the present time. 

With recent developments in analytical instrumentation these criteria are being increasingly fulfilled by physicochemical spectroscopic approaches, often referred to as whole-organism fingerprinting methods.910 Such methods involve the concurrent measurement of large numbers of spectral characters that together reflect the overall cell composition. Examples of the most popular methods used in the 20th century include pyrolysis mass spectrometry (PyMS),11,12 Fourier transform-infrared spectrometry (FT-IR), and UV resonance Raman spectroscopy.16,17 The PyMS technique... 

However, now and then analytical chemists feel uneasy with such kinds of definitions which do not reflect completely the identity and independence of analytical chemistry. Chemists of other branches (inorganic, organic, and physical chemists) as well as physicists and bioscientists also obtain information on inanimate or living matter using and developing high-performance analytical instruments just as analytical chemists do. 

The computer age has brought about considerable innovation in the operation of laboratory instrumentation. One consequence of this is the wider acceptance and utilization of the optical microscope as a quantitative analytical instrument. A brief literature survey illustrates the diversity of disciplines and optical methods associated with the development of computer interfaced optical microscopy. This is followed by a description of how our methods of fluorescence, interferometry and stereology, nsed for characterizing polymeric foams, have incorporated computers. 

Although the condensation of phenol with formaldehyde has been known for more than 100 years, it is only recently that the reaction could be studied in detail. Recent developments in analytical instrumentation like GC, GPC, HPLC, IR spectroscopy and NMR spectroscopy have made it possible for the intermediates involved in such reactions to be characterized and determined (1.-6). In addition, high speed computers can now be used to simulate the complicated multi-component, multi-path kinetic schemes involved in phenol-formaldehyde reactions (6-27) and optimization routines can be used in conjunction with computer-based models for phenol-formaldehyde reactions to estimate, from experimental data, reaction rates for the various processes involved. The combined use of precise analytical data and of computer-based techniques to analyze such data has been very fruitful. 

Progress in all areas of additive analysis is very much associated with instrumental development. The last few years have seen major developments in the sensitivity of LC-MS and other MS-based techniques. Such developments are sure to continue. On the down side these analytical techniques provide a large amount of information obtainable per analytical run and therefore there is an increasing need for more automated accurate analytical equipment to improve data management. 

There are a variety of analytical methodologies developed for the analysis of emerging contaminants selected for this chapter. In almost all cases, the instrumental analysis is based on the use of GC or LC coupled to MS or MS-MS. The selection of one or another technique depends primarily on the physicochemical properties of the compounds. We summarize the more recently developed methodologies for each of the families (Table 1). 

The development of scientific procedures that are able to use very minute samples (a few micrograms), together with the increased availability of advanced analytical instrumentation, have led to great interest in the chemical study of materials used in cultural heritage. This has given rise to a sharp increase in research studies at the interface between art, archaeology, chemistry and the material sciences. As a result, successful multidisciplinary collaborations have flourished among researchers in museums, conservation institutions, universities and scientific laboratories. 

The computerized systems, both hardware and software, that form part of the GLP study should comply with the requirements of the principles of GLP. This relates to the development, validation, operation and maintenance of the system. Validation means that tests have been carried out to demonstrate that the system is fit for its intended purpose. Like any other validation, this will be the use of objective evidence to confirm that the pre-set requirements for the system have been met. There will be a number of different types of computer system, ranging from personal computers and programmable analytical instruments to a laboratory information management system (LIMS). The extent of validation depends on the impact the system has on product quality, safety and record integrity. A risk-based approach can be used to assess the extent of validation required, focusing effort on critical areas. A computerized analytical system in a QC laboratory requires full validation (equipment qualification) with clear boundaries set on its range of operation because this has a high... 

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