The first liquid chromatographic method with postcolumn derivatization for the simultaneous determination of peroxycarboxylic acids is described. Aliphatic peracids with chain lengths from C2 to C12 are separated by HPLC on a reversed-phase C18 column with acetonitrile/water gradient elution. For improved peak shape, tetrahydrofuran and acetic acid are added to the aqueous eluent. After chromatographic separation, the peroxycarboxylic ...