On-Line Automation

W. Haasnoot, M. E. Ploum, R. J. A. Paulussen, R. Schilt and F. A. Huf, Rapid determination of clenbuterol residues in urine by high perfoi mance liquid cliromatography with on-line automated sample processing using immunoaffinity chromatography , 7. Chromatogr. 519 323-335 (1990). 

On-line automation of sample preparation and chromatographic analysis steps... 

Despite the difficulties of on-line automation, the need to develop such systems is considerable. The increase in the number of different compounds that must be determined and the number of samples required for a meaningful survey or laboratory study make it essential to improve the quality and throughput of samples. There are a number of stages in fully automating trace organic analysis. Autosampler LC or GC-data systems as GC-MS or GC-ion trap detector (ITD) are well established and require no further elaboration here [191, 203, 495]. 

With this on-line automated method, more than 250 samples have been analyzed unattended in a 24 h period. Good results are obtained over a 10-1000 ng/mL range. The LOQ and LOD are 190pg and 58pg, respectively. Accuracy and precision values are 9.0% or better over the entire range of the assay. 

Sandahl, M., L. Mathiasson, and J.A. Jonsson. 2002. On-line automated sample preparation for liquid chromatography using parallel supported liquid membrane extraction and microporous membrane liquid-liquid extraction. J. Chromatogr. A 975 211-217. 

The advantages of on-line automation are the achievement of time savings in relation to the chromatographic method development time. The software can make decisions at any time of the day or night and can immediately communicate this information to the instrument after the completion of the experiment. There is also a more subtle benefit to the link of optimization software to the chromatography data system. Method development wizards with drop-down menus/user-defined fields can simplify the process of configuring the instrument sequence/method prior to a method development session. 

Herzenberg, C. L. Application Potential of Advanced Instrumental Methods for On-Line Automated Composition Analysis of Solid/Liquid Fossil Energy Process Materials Volume III Non-Nuclear Methods" Argonne National Lab. ANL/FF-83-22, 1984. 

I. Ruisanchez, J. Lozano, M.S. Larrechi, F.X. Rius, J. Zupan, On-line automated analytical signal diagnosis in sequential injection analysis using artificial neural networks, Anal. Chim. Acta 348 (1997) 113. 

If the analytes of interest are volatile or semivolatile, solvent extraction is not always necessary, and head-space techniques (HS) can be applied for the analysis, typically utilizing GC as the final analytical step. HS analysis can be defined as a vapor-phase extraction, involving ftrst the partitioning of analytes between a non-volatile liquid or solid phase and the vapor phase above the liquid or solid. The vapor phase is then transferred further and either analysed as vapor or (ad)sorbed to an (ad)sorbent. The head-space techniques have been widely utilized in the analysis of volatiles, such as fi agrances and aroma compounds, in various food and agricultural samples (81-84). The dynamic head-space (DHS), or purge-and-trap technique, is easily coupled on-line with GC. In an on-line system, desorption of trapped analytes for subsequent analysis is usually performed using on-line automated thermal desorption (ATD) devices. 

Examples of the use of analytical chemistry techniques are drawn from such areas as life sciences, clinical chemistry, air and water pollution, and industrial analyses. Analytical chemistry becomes meaningful when you realize that an incorrect blood analysis may endanger a patient s life, or that an error in quality control analysis may result in serious financial loss for a manufacturer. Millions of dollars are saved in the chemical industry by performing on-line automated analyses of chemical processes, to assure maximutn efficiency in chemical production. 

Figure 4.1 illustrates some of the ways In which the chief preliminary operations (sample collection and treatment) can be connected to each other and their relationship to the Instrument or analyser. Complete automation is achieved when no clear distinction can be established between all three stages. Human Intervention, on the other hand, Is minimal In on-line automation (e.g. via a sampler). Finally, off-line configurations Involve the Independent development of each preliminary operation in an automatic module liable to be connected on-line to a sampler however, in some of the connections, samples are transferred manually. Table 4.2 lists some of the different possibilities resulting from the various connections and separation techniques, Illustrated with examples corresponding to the different sections of this chapter. 

Generic Safety Issue (GSI) I.D.5 (3) in NUREG-0933 (Reference 1), addresses the benefit to plant safety and operations of continuous on-line automated surveillance systems. 

In view of the above considerations the main motivation behind developments of new characterization methods, ultimately leading to advances in andytical technologies and sciences, is to 1) develop new techniques for qualitative and quantitative analyses and demonstrate thdr selectivity and sensitivity 2) develop multi-fimctional methods allowing simultaneous analysis of a specimen 3) develop automated multi-fimctional techniques and 4) develop on-line automated quality control techniques. Although one could argue that these analytical areas are relatively independent, history has shown that an interplay of new instrumentation ideas and teclmological advances resulted in the development of new techniques, followed by multi-functional approaches. 

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