General Requirements for On-line Column Packings

Sorbents used successfully as packing materials for batch column preconcentration purposes are not always adaptable to FI column preconcentration systems. The special requirements for FI preconcentration sorbents may at least include the following  

Requirements for packing materials may be less stringent when the columns are used for separation purposes where the interferents are removed by the column, and no preconcentrations are involved. In such applications the column may be used for extended periods without regeneration, and in extreme cases may even be discarded when they are exhausted. 

In addition to the requirements mentioned above, packings used in sorbent absorptiometry should be transparent enough to transmit adequate light energy at the wavelengths where measurements are made. 

The Japanese product Muromac A-1, which has the same imminodiacetic functional group as Chelex-100, was reported to be free from the troublesome swelling properties of the latter, and has been used successfully in a number of AA and ICP spectrometric applications with column preconcentrations [13,14]. A prototype column packed with another imminodiacetic resin was used in a preconcentration system for ICP-MS [66]. 

Ouinolin-8-ol immobilized on silica was used for on-line preconcentration purposes with an ICP-MS system [17]. Isotope dilution and standard addition methods were applied for the determination of trace metals in a sea water standard reference material. A similar ion-exchanger was used for on-line preconcentration of cobalt with catalytic sp ectrophotometric determination [18]. 

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