The effects of ion-exchange filter papers and of heavy atoms on room-temperature phosphorescence of several indoles

Room-temperature phosphorescence (r.t.p.) of twelve indoles on different ion-exchange filter papers is examined. Anion-exchange filter paper Whatman DE-81 gives the largest r.t.p. signals in the presence of iodide; S & S 903 paper treated with diethylenetriamine-pentaacetic acid or supported carboxymethylcellulose resin are less useful. The heavy atom effect is necessary to observe analytically useful r.t.p. signals of indoles, with the trend iodide > thallium(I). Lifetimes of the r.t.p. of indoles are very short, in the millisecond range, and show two components. Absolute limits of detection between 0.2 and 14 ng show r.t.p. to be sensitive and simple analytical technique for these compounds.