MEASUREMENT OF LANTHANUM AND LUTETIUM IN METAL-CONTAINING TEXAPHYRINSBY INDUCTIVELY-COUPLED PLASMA-MASS SPECTROMETRY

Lanthanum (La) and lutetium (Lu) texaphyrins have potential applicatio ns in photodynamic therapy as photosensitizers to identify and treat m alignant tumors. Few studies have been done to determine tissue levels of La and Lu. This report describes a sensitive method by; inductivel y coupled plasma-mass spectrometry (ICP-MS) for measuring Za and Lu in liver homogenates after in vitro addition or in vivo treatment with t hese metal-containing texaphyrins. The lower detection limit was 0.5 n g/mL for both pure La and Lu standards tissue digestates. This !CP-MS method will facilitate the study of tissue distribution of La and Lu t exaphyrins and can be adapted to determine tissue levels of other trac e metals in metal-incorporated texaphyrins such as those containing ma nganese (Mn), cadmium (Cd), gadolinium (Gd), or terbium (Tb). This tec hnique can also be used to establish the purity of the synthesized com plex by determining the metal composition.