Instruments, development

The recent development and comparative application of modern separation techniques with regard to determination of alkylphosphonic acids and lewisite derivatives have been demonstrated. This report highlights advantages and shortcomings of GC equipped with mass spectrometry detector and HPLC as well as CE with UV-Vis detector. The comparison was made from the sampling point of view and separation/detection ability. The derivatization procedure for GC of main degradation products of nerve agents to determine in water samples was applied. Direct determination of lewisite derivatives by HPLC-UV was shown. Also optimization of indirect determination of alkylphosphonic acids in CE-UV was developed. Finally, the new instrumental development and future trends will be discussed. 

Table 33. Summary of wave profile instrumentation developments.

Even before a new organic substance has its structure determined, it must be purified by separating it from solvents and all contaminants. Purification was an enormously time-consuming, hit-or-miss proposition in the 19th and early 20th centuries, but powerful instruments developed in the last few decades now simplify the problem. 

We are first concentrating on commercially-available instrument technologies providing in situ measurements in polymer reactors, as opposed to those requiring new instrument development or external sampling loops. 

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). 

UV/VIS absorption spectroscopy, pioneered by Beckman (1941), is one of the oldest and most widely used instrumental techniques, despite being regarded by some analysts as obsolete. Recently there has been a renaissance in UV spectroscopy with many new techniques, instruments and data processing methods [8]. Modem highest specification UV/VIS absorption and fluores-cence/phosphorescence spectrometer instruments extend their wavelength region from the far UV (175 nm) into the NIR region (1100 nm). Small footprint UV/VIS spectrometers (200-1100 nm) are now available. Paul [9] has traced the history of UV/VIS instrumental developments. 

Instrumental developments concern micro ion traps (sub-mm i.d.) [193], extension of the mass range, mass resolution and capture efficiency for ions generated externally. Fast separations at very low detection levels are possible by means of hybrid QIT/reToF mass spectrometry [194]. 

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 manufacturers of electroanalytical instrumentation cannot always immediately satisfy the experimenter s requirements, but often this can be remedied by instrumental development in mutual contact. An illustrative example is the construction of the carbon-fibre microelectrodes (MFC) by... 

Microprobe analysis was initially developed at the University of Paris by R. Castaing, who fitted an X-ray spectrometer to a converted electron microscope in the early 1950s, and the first commercial instrument, developed in France by the Cameca company, appeared in 1958. The following years saw commercial instruments produced in the UK, USA and Japan. 

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. 

FIGURE 6.15 (a) Schematics of RRS instrument developed for selective in vivo measurements of lycopene... 

With recent instrumental development, such as fast LC, fast GC and two-dimensional gas chromatography (GCxGC) and advanced tandem hybrid MS detection systems (i.e., QqTOF, QqLIT, Orbitrap) the analysis of complex mixtures... 

In addition, recent instrumental developments have made it possible to perform kinetic measurements on the millisecond time scale. 

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. 

A general term applied to a variety of instruments for determining the curing characteristics of elastomers. The spelling Vulkameter refers to a particular instrument developed by Farbenfabriken Bayer and marketed by Agfa Ltd. Vulcanisate... 

The nanometer- to micrometer-scale dimensions of supramolecular assemblies present many challenges to rigorous compositional and structural characterization. Development of adequate structure-property relationships for these complex hierarchical systems will require improved measurement methods and techniques. The following areas constitute critical thrusts in instrument development. 

Most chemists tend to think of infrared (IR) spectroscopy as the only form of vibrational analysis for a molecular entity. In this framework, IR is typically used as an identification assay for various intermediates and final bulk drug products, and also as a quantitative technique for solution-phase studies. Full vibrational analysis of a molecule must also include Raman spectroscopy. Although IR and Raman spectroscopy are complementary techniques, widespread use of the Raman technique in pharmaceutical investigations has been limited. Before the advent of Fourier transform techniques and lasers, experimental difficulties limited the use of Raman spectroscopy. Over the last 20 years a renaissance of the Raman technique has been seen, however, due mainly to instrumentation development. 

One of the best-known commercial instruments developed for organic carbon determinations is the Beckman total carbon analyser, which utilises an analysis scheme developed by Van Hall and co-workers [57,99]. This instrument works reasonably well in fresh water. It has become a standard instrument in pollution control and water treatment [103]. The Beckman instrument has not worked as satisfactorily for seawater because of the latter s high carbonate and low organic content. 

Another instrument developed by the Precision Scientific Co. was based upon the work of Stenger and Van Hall [99,104], Experience has shown that application of the Beckman and Precision Scientific Co. instruments to concentrated or saturated brine solutions leads to erratic and unreliable results. There are several possible reasons for this (1) the catalyst will rapidly become coated with sodium chloride (2) oxidation of Cl to chlorine will occur and (3) volatile organics may not all be trapped by the solid catalyst. 

However, many recent instruments are still not considered satisfactory, since professional developers in the field of high-throughput screening (HTS) want to use the full performance of the latest generation of robots and computers for automation. This results in new instrumental developments, like the possibility of reading not only 96, but 384 or even 1536 wells plates as well as DNA chips, very rapidly (in a minute or so) and repeatedly without any mechanical failures. Hence, in the eyes of company scientists developing new assays, many present-day instruments still correspond to an intermediate stage of development. For research laboratory scientists, on the other hand, the actual equipment offers excellent performance. 

Some of these measures are part of larger, semistructured interviews administered by the therapist. The most commonly used assessments in this category are a family of instruments developed mainly in the Veterans Administration (VA) hospital system. The first instrument in this family is known as the Addiction Severity Index (ASI McLellan et al., 1985). The ASI assesses for a wide variety of biographical data, so it has the advantage of potentially being used as part of an intake interview. The ASI asks about consequences in a wide variety of life domains, and determines recent and lifetime patterns of drug and alcohol use. The ASI also detects recent and lifetime occurrence of problems in these different life domains (e.g., work). Each domain can be scored for the severity of the problems based upon the responses of the client and the clinical judgment of the interviewer. The ASI can be administered by computer to provide for rapid interpretation of answers. 

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