Extraction-fluorimetric determination of microgram amounts of thallium with 2-phenylbenzo[8,9]quinolizino[4,5,6,7-fed]phenanthridinylium perchlorate

In 0.5 M hydrochloric acid medium, thallium(III) forms with 2-phenylbenzo 8,9]quinolizino4,5,6,7-fed]phenanthridinylium perchlorate (PQPP) an ion-association compound which is extractable in isoamyl acetate. The extracted ion-pair has a mole ratio Tl/PQPP in 1:1 and has been used for the spectrofluorimetric determination of thallium in the concentration range 0.06–1.6 μg per 5 ml of organic layer. The interference of a large number of foreign ions has been investigated. The method is sensitive, accurate, precise, and specially useful for the determination of thallium in different materials with low contents of this element.