DETERMINATION OF HEMIN, PROTOPORPHYRIN IX, AND ZINC(II) PROTOPORPHYRIN IX IN PARMA HAM USING THIN LAYER CHROMATOGRAPHY

Abstract

An effort was undertaken to investigate a possibility to quantify hemin, protoporphyrin IX (PPIX), and zinc(II) protoporphyrin IX (Zn(II)PPIX) by means of thin-layer chromatography (TLC). All these porphyrins naturally occur in meat and meat products, and they are known for being metabolically interrelated in a not yet fully understood fashion. In view of the results of a current research in meat chemistry, it seems most likely that Zn(II)PPIX is responsible for the red color of Parma ham (a traditional Italian dry ham). This discovery prompted a novel concept that Zn(II)PPIX might replace sodium nitrite and potassium nitrate in the function of the red color-forming pigment, the latter two compounds traditionally used for the same purpose in meat industry, yet known for the formation of the carcinogenic N-nitrosamines as well. In this study, a novel analytical system was proposed for the successful baseline separation of hemin, PPIX, and Zn(II)PPIX, and a possibility was tested of quantifying these three porphyrins in Parma ham. To this effect, the calibration curves were established for the porphyrin standards. Due to the recognized photosensitivity of hemin, PPIX, and Zn(II)PPIX, extraction of these three compounds from Parma ham and the thin-layer chromatographic procedure were carried out in the darkness, although a complete blackout was not always possible. One problem remained unsolved in this study, namely the selection of a proper (preferably a visible light resistant, hence a nonporphyrin) internal standard (IS) for the performance of the recovery procedure for hemin, PPIX, and Zn(II)PPIX contained in the meat matrix. Finally, it was concluded that the elaborated TLC procedure can successfully be implemented to quantification of hemin and PPIX in Parma ham (and in the other meat products as well).