Automatic analyser

In preceding chapters we have indicated which tools are nowadays being used routinely or currently are under development. General trends are higher sensitivity, more information, and faster and further automation. Automatic analyses are nice (sample in, report out), but interactive analysis tools are better. It is not realistic to expect the need for more analyses. Some future needs are more reliable quantitation, reference materials and simplification of data management. A particular problem in additive analysis concerns accuracy and traceability. In many cases, extractable rather than total concentration is determined. There are still many quantitative analytical methods waiting to be developed. It is here that the field will advance. Table 10.31 lists some proposed (r)evolutionary developments in polymer/additive analysis. 

If proper attention is given to calibration and standardization, a well-designed, constructed and maintained automatic analyser will operate reproducibly over long periods in the hands of a trained operator. 

These analysers resemble hquid and gas chromatographs, although their background is markedly different. They differ from discrete automatic analysers (DAA) in various respects, namely the fashion in which samples are transported and mixed with diluents and reagents, the manner in which carry-over between samples and reagents is avoided and the type of detection used. 

Although some of these elements, such as the heater, continuous separator, dehuhhler or microprocessor, are not indispensable, the rest are fundamental to the design of continuous segmented analysers. Although developed primarily for a chnical market, the concepts found many apphcations in the industrial area as well. TTie Laboratory of the Government Chemist (LGC) has estahhshed many automatic analyses for routine use using these concepts [29—31]. 

The economic treatment discussed so far is hmited to analytical laboratories where samples are received from an outside source it will not apply to laboratories attached to processing plants performing quahty-control analyses. The cost of the automatic equipment, in these cases, wiU be small in relation to the plant cost, and it wiU be the improved precision of analysis and speed of response that wiU have the greatest economic significance. Automatic analysers in production hnes are ideal for quality control, and there is ample scope for additional automation. However, this is an area where the... 

Figure 9.28— ll NMR instrument used for routine analyses. Automatic analyser based on pulsed NMR used to quantify water and lipids in food technology. (Reproduced with authorisation of Bruker.)... 

The pulser peak method gives better estimates of the effective counting time than the methods implemented in the ADC converter which estimate the time when the gate of the ADC is closed electronically, since in the former the influence of the pile-up effect on the peak areas is taken into account. However, an automatic analysing procedure evaluating the pulser peak area introduces systematic effects which are caused by the distortion of the shape of the pulser peak. These systematic effects are reflected in the dependence of the count rate from a source located at a fixed position on the total count rate in the spectrum. The effects arise only partially from the difference between the calculation of the pulser peak area and the areas of other peaks in the spectrum. The other sources of systematic effects originate in the difference between the pulser peak shape and the shapes of other peaks in the spectrum and in the relatively low background near the pulser peak. 

Separation of diastereomic Gly.Ala.Leu was kindly carried out by Dr R.P. Ambler, Department of Molecular Biology, University of Edinburgh, using a Beckmann 120 C automatic analyser. 

Automatic analysers are nowadays universally used in oenological laboratories, and this includes control laboratories who often employ these techniques for screening purposes before applying reference methods when limit values have been identified. 

This can be used to automatically analyse single beads with no knowledge of M.Wt Fig. 5.26 shows the cluster analysis result on four single beads that were analysed in triplicate. The TIC traces only show responses that fitted with the isotopic difference criteria and by selecting these peaks , mass spectra are generated depicting the doublets only with the M.Wt values. 

Rocks, B.F. and Riley, C. (1986). Automatic analysers in clinical biochemistry, Clin. Phys. Physiol. Meas. 7, 1-29. 

R132 Assmann, G., Brinkers, H., Schulte, H. and Carstensen, C.A. (1989). Comparison of the reflectance method (Reflotron reflectance photometer) with the absorbance method (automatic analysers) for the determination of cholesterol. J. Clin. Chem. Clin. Biochem. 27, 961-966. 

A system of automatic analysers should be employed to continuously monitor the ambient air and all phases of the operation. 

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