The separation by thin-layer chromatography of trace metals as their tetraphenylporphyrin chelates

The tetraphenylporphyrin chelates of iron, cobalt, manganese, nickel, zinc, copper, rhodium lead, cadmium and mercury were prepared and their chromatographic behaviour investigated using four different adsorbents and eleven different solvent systems. Mixtures of lead, cadmium and mercury chelates exhibited isographic behaviour in all conditions; mixtures of the other metal chelates were adequately resolved on silica (MN Polygram Sil SHR) by the solvent system light petroleum (b.p. 80-100 degrees)-toluene-acetic acid-water (66:33:85:15, v/v, upper phase). The intense colours of the chelates permit their visual detection at levels of about 10(-10) moles; using the integrated ion-current mass spectrometric procedure, as little as 10(-14) moles of metal could be detected and assessed.