Molecular-screening activated carbon

Isotherms are normally developed to evaluate the capacity of the carbon for the adsorption of different contaminants. Data are obtained in batch tests, which determine the equilibrium relationship between the compound adsorbed on the carbon and that remaining in solution. The isotherms are used as screening tools to determine which carbon is suitable for a given application. Batch equilibrium tests are often complemented by dynamic column studies to determine system size requirements, contact time, and carbon usage rates [19]. Other parameters that are used to characterize activated carbons for water treatment include phenol number, an index of the ability to remove taste and odor, and molas.ses number, which correlates with the ability to adsorb higher molecular weight substances. However, these parameters still do not reflect performance in service, and they can only be considered as guidelines. 

Relatively few applications can be found in this field that involve the coupling of microdialysis to biosensors, especially electrochemical ones. The major problem is always the need to exclude electrochemically active substances, which can be present in the external medimn, and, because of their low molecular weight, can easily cross the membrane of the microdialysis probe. Some attempts to overcome this problem have been reported by Csoregi [187], who coupled a microdialysis probe equipped with a polysulphone membrane with a 5000 Da cut-ofiF to a carbon paste electrode with wired GOD, thus excluding many interfering substances. Similarly, Rohm [188] has assembled a screen-printed biosensor for lactate based on an ultraviolet-polymerizable enzyme paste and then applied it in an FIA system for the on-hne monitoring of cell cultivation. 

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