Catalytic performance, importance reproducibility

Derivatization reactions can be performed either pre- or postcolumn. As outlined by Brinkman, there are important advantages to using the postcolumn techniques whenever possible (68). First, the analytes can be separated in their original form, which often permits the adoption of published separation procedures. Second, artifact formation is generally not a serious problem, in contrast to precolumn derivatization, where it increases the separation difficulty and causes problems with quantitation. Third, the reaction does not need to be complete and the reaction products need not be stable the only requirement is reproducibility. Several reaction principles have been extensively applied. These include true chemical derivatization such as with dansyl chloride or o-phthalaldehyde UV irradiation, which can convert the analyte of interest into a more easily detectable species solid-phase reactions, including catalytic reactions such as with the use of immobilized enzymes and chemiluminescence techniques. 

Sulfur and halogens are important in catalysis, being capable of behaving as poisons and promoters in different catalytic systems. A study of the effect of submonolayer quantities of these elements on the performance of several catalysts is currently in progress. Both sulfur and halogens may be conveniently and reproducibly deposited on the catalyst surface by the in situ solid-state electrolysis of the respective silver compound. 

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