The general principle of postcolumn derivatization and its advantages in food analysis was thoroughly described by Galensa in the book “Food Biosensor Analysis” (Wagner and Guilbault, 1994). In his working group, the specific coupling of an HPLC system with an integrated sulfite oxidase reactor between the column and the detector was first described in the dissertation thesis of Pabel (1993). Several modifications and advancements of the method were later presented by Weßels (Weßels et al., 1995 and Weßels, 1997) again in the working group of Galensa. Further optimization of the method was presented by Patz et al. (1997).