Analytical chromatography, species-specific

Statistical process control methods are applied to preparative chromatography for the case where cut points for the effluent fractions are determined by on-line species-specific detection (e.g., analytical chromatography). A simple, practical method is developed to maximize the yield of a desired component while maintaining a required level of product purity in the presence of measurement error and external disturbances. Relations are developed for determining tuning parameters such as the regulatory system gain. 

Figure 1. Use of analytical chromatography as an on-line species-specific detector for a preparative chromatographic process.

Hyphenated techniques are the analytical methods most frequently used today for elemental speciation. For that purpose, a separation technique, such as high-performance liquid chromatography (HPLC), gas chromatography (GC), capillary electrophoresis (CE), or gel electrophoresis (GE), is coupled on-line with an elemental detection method, such as ICP-MS [67]. Hyphenated ICP-MS techniques can also be combined with the isotope dilution method for quantification of elemental species. Two different spiking modes are possible, the species-specific and spedes-unspedfic mode. Rottmann and Heumann were the first to present a setup for H PLC-ICP-IDMS enabling the use of these two spiking modes [68] (Figure 8.14). 

With today s advanced analytical procedures, it is possible to describe the composition of these fuels in considerable detail. By combining several sequenced liquid chromatographic separations with gas chromatography-mass spectroscopy and by using specific gas chromatographic detectors for sulfur compounds, it has been possible to identify the majority of individual sulfur species in some fuels (12-19). A typical separation scheme is shown... 

In 1985, the results of a study done at Balazs Analytical Laboratory (Bal-Lab) (4) and in Plessey Research (5) led to the specification of metallic materials in water. At that time, the metals that were analyzed were those thought most likely to be present in and deleterious to ICs. Because both ion chromatography and GFAA are very time consuming, the evaluation of only nine or ten metals and six to eight nonmetallic species at the part-per-trillion level is all that one would do normally to get results within a reasonable time. Without sample concentration, analysis at this level will be at the limits of these methods. 

Affinity chromatography techniques have shown less utility in analytical testing than in preparative separations for a variety of reasons, including cost and the difficulty of validating consistent operation as the column changes over time. Protein A affinity has been commonly used to quantitate the total antibody content of either ascites or cell culture fluids. To provide guidance in the development of a purification process, specific immunoaffinity resins are either available or can be readily prepared to quantitate the levels of unrelated protein contaminants. To rapidly determine what the active species in a mixture is, a monoclonal antibody that... 

The problems increase when the analyzed object contains other species with chemical properties similar to those of the analyte. Often there are no specific procedures for a given compound, and the analytical process should start with separation procedures. Among these are, in the first line, various useful chromatographic procedures, which constitute a very important component of the whole analytical process. Therefore, the rapid progress in organic trace analysis in the second half of the twentieth century was coimected with the development of chromatography and physical methods for species identification. 

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