DETERMINATION OF PYRROLE DERIVATIVES AND HYDROXYPROLINE WITH 4-(DIMETHYLAMINO)BENZALDEHYDE IN A MICELLAR MEDIUM

The spectrophotometric determination of pyrrole derivatives and hydrox yproline with 4-(dimethylamino) benzaldehyde (Ehrlich's reagent) in a sodium dodecyl sulphate micellar medium is studied. Pyrrole and pyrrol e-2-carboxylic acid were used as model compounds for the optimization of the procedure. In the micellar medium with 0.2 M HCl at 90 degrees C, pyrrole reacts in 15 min, whereas a HCl concentration larger than 5 M is required in the absence of the surfactant. The sensitivity incre ases from 1.3 to 5.6-fold with respect to the use of a non-micellar me dium, for some pyrrole derivatives. The procedure is applied to the de termination of hydroxyproline in meat samples.