Sorbent extraction has been automated by Sequential Injection in two ways:
1) using microcolumns or cartridges (Hansen 2006, Miró 2008, Motomizu 2009)
2) in BI renewable column format, as described in this section
For both applications, the Lab-on-valve format proved to be an excellent platform for the miniaturization and automation of this technique. Since successful method development in renewable or traditional column format depends on the understanding of the underlying chemical reactions, the reader is encouraged to consult the following comprehensive review, which is helpful in selecting optimum conditions for trace metal analysis in sea and fresh water.