Autoanalysis

There is usually no problem of access to basic laboratory instruments and associated glassware, however, the only means of handling large numbers of tests is to apply some form of automation. An added advantage is that it improves the analytical precision and reproducibility. The most suitable technique has been based on the segmented continuous-flow principle invented by Skeggs (1957), and which was first marketed as the Technicon AutoAnalyzer. The system consists of a number of modules powered from a stabilized 110 V supply, and a typical layout is shown in Fig. 1.1. 

More information can be found on the manufacturer s website http //www.bran-luebbe.de/en/autoanalyzer.html The price range for a basic system with a colorimeter is about 20k to 27k depending on options (e.g. PC and flame photometer) and whether educational discount applies. 

Other manufacturers of segmented-flow analysers are Burkard Scientific, see http //www.burkardscientific.co.uk/Analytical/Systems Analysers SF A2000.htm 

It is possible to build a basic system with chart-recorder output using components from various manufacturers. Suppliers of used equipment are another possible source. Sometimes there are equipment auctions but, having learnt from bitter experience, unless one can actually go and see (and preferably test) the items listed in the catalogue, this method of purchase should be avoided. Very often parts will be missing and, being obsolete, no longer obtainable. Used equipment suppliers always include some form of guarantee, and that is worth its cost. Some used or refurbished equipment suppliers are listed in Appendix 1. 

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Instruments specially constructed for automatic titration or autoanalysis in general will be treated in Part C. 

Cyanogen bromide is moderately endothermic (AH°f (g) +50 kJ/mol, 0.47 kJ/g) and shows evidence of instability. The plastic cap of a bottle stored in a laboratory for several years on a high shelf, occasionally at 31°C, shattered and drove fragments into the shelf above [1]. This instability was confirmed, and a procedure outlined to obviate the use of the bromide in autoanalysis by generating cyanogen chloride on demand from Chloramine-T and potassium cyanide [2], A 50 wt% solution of the bromide in chloroform is a stable and convenient form for use [3], See Cyanogen chloride... 

Petts KW (1979) The determination of oxidised nitrogen and nitrite in estuarine waters by autoanalysis, Technical Report TR 120. Water Research Centre, Medmenham Laboratory, UK... 

Using autoanalysis, ammonium ions are reacted with sodium phenate and sodium hypochlorite to give the indophenol blue colour by the Berthelot reaction (Berthelot, 1859). 

The extraction method of Hislop and Cooke (1968), has been outlined in Chapter 4, Phosphate extractants. A blank determination without soil should be carried out. The autoanalysis manifold is shown in Fig. 5.4. Some adjustments to dilution and/or readout sensitivity may be necessary to handle both... 

Ammonium molybdate - sulphuric acid autoanalysis reagent - dilute 100 ml of the ammonium molybdate - sulphuric acid stock reagent to 1 I with water and mix. 

Switch on the modules for autoanalysis and commence pumping reagents. The wash solution is saturated benzoic acid. Load the standards into a sample tray and analyse at a rate of 20 samples per hour, adjusting the sensitivity of the detection-readout to bring the baseline and top standards on scale. If the samples are all low, the sensitivity should be increased and appropriate lower standards used. After a baseline, analyse a tray of samples plus standards, and follow with a baseline before analysing the second tray of samples and standards. Conclude by aspirating the wash solution to obtain a final baseline. 

We will describe the autoanalysis method based on Faithfull (1971a) which uses the same Kjeldahl acid digest solution as that used for the nitrogen determination (see Discussion 7.7). The proper development of the yellow colour of the phosphovanadomolybdate complex is sensitive to the pH,... 

Method 7.14. Determination of water soluble carbohydrate by autoanalysis... 

Steve Smith (reference), Stapledon Library, Institute for Grassland and Environmental Research, Aberystwyth, UK Stuart Smith (autoanalysis methodology). Divisional Manager, BL-Analytics, Bran+Luebbe, UK... 

Fergusson, A. (2000). Accompanied autoanalysis An empathic approach. Ethical Human... 

Fergusson, A. (2002). Accompanied autoanalysis An empathic approach to helping deeply disturbed persons. In P. Breggin, G. Breggin, F. Bemak, (Eds.). Dimensions of empathic therapy, (pp. 89-100). New York Springer Publishing. 

A third major development which was necessary for the commercial implementation of this instrument, was the further development of the software for data analysis. In the initial work described above, the software was developed to the point where the user could read the sequence from the plots of dye concentration vs. time. However, in order for this method to be useful, it was essential that the software automatically call the sequence. Indeed, this capability was the major impetus behind the development of the method, intended to eliminate the need for laborious manual interpretation of data. The problem of autoanalysis is a nontrivial exercise in pattern recognition. At this time, the autoanalysis software developed at ABI and employed on the commercial instrument is approximately 98% accurate, and further improvements under development are expected to increase the accuracy substantially. 

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