Sequential analyser analytical methods

Time-related variables are critical in GD work. One of the key features of any analytical method used in a production facility is the sample analysis time. Because GD is a kinetic-based system, the evolution of the plasma processes to, hopefully, an equilibrium situation, is of special concern. It is sufficient to say that any analysis (spectral acquisition) performed in a sequential mode requires that the plasma reach a steady state before analyses can be started — which is obviously arguable for simultaneous detection. Thus, for most analyses, the plasma stabilization time can be a substantial fraction of the overall sample analysis time. 

As all elements present in the radiation source emit their spectrum at the same time, from the principles of AES it is clear that it is a multielement method and is very suitable for the determination of many elements under the same working conditions. Apart from simultaneous determinations, so-called sequential analyses can also be carried out, provided the analytical signals are constant. Sequential and... 

Figure 5,2 Examples of the laboratory systematic errors when samples are collected in numeric and random number order, (a) Shows error due to analytical drift and (b) carry over contamination during sample preparation after the preparation of a high sample. The random numbering of samples makes it easier to identify systematic laboratory errors. If the samples are collected and analysed in sequential order the results look like naturally occurring anomalies while the random numbering method tends to distinguish such errors as isolated highs.

Consolidation of this technique as an effective, widespread analytical tool is bound to rely on future, sequential developments such as the following (a) the gathering of sufficient research experience to compile a cookbook of methods where potential users can search for solutions to specific problems and (b) the commercialization of inexpensive pervaporation modules meeting the requirements of a variety of samples and analytes. The development of such methods and theoretical studies should turn pervaporation into a useful tool for routine environmental, clinical, food and industrial analyses. 

One type of improvement is sequential analysis to use a single sample for analyzing several radionuclides. This approach is beneficial if the sample amount is hmited by collection, shipping, or handling restrictions, or the largest possible amount is required for adequate detection sensitivity, or the initial analytical steps are identical for several radionuclides. The method must be tested to assure that cross-contamination and other possible interference among the analyses for the several radionuclides are minimal and/or acceptable. 

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