Excitation and fluorescence spectra, excited singlet state, protolytic equilibrium constants for the equilibria between the cations and zwitterions, fluorescence quantum yields, and fluorescence limits of detection for 8-hydroxyquinoline and 29 of its derivatives are given. The derivatives studied include fluoro, chloro, bromo, iodo, sulfo, and thiocyano substituents in either the 5-or the 7-positions on the ring or in both positions and methylation of the phenolic oxygen at the 8-position on the ring. Excited singlet state pK,* values range from -6.2 for the 5-iodo-7-sulfo-8-hydroxyquinoline to -9.6 for the 5,7-disulfo-8-hydroxyquinoline. Analytical detection limits for the 8-hydroxyquinoline and its derivatives in concentrated sulfuric or perchloric acid were between 10-6 to 10-EM. Fluorescence quantum yields varied as expected from a high value (0.31) for 8-hydroxyquino-

Samples containing Ag, Be, Bi, Cd, Cu, Ga, Hg, Mg, Pb, Tl, and Zn are vaporized from a tungsten or platinum loop into an argon stream and excited by radiation from electrodeless discharge tubes to produce atomic fluorescence. The integrated atomic fluorescence signals are independent of loop material and loop temperature, and nearly independent of anion type, sample nature, and argon flow rate. The device may have use for fundamental studies for measurement of quantum yields as well as for applied studies of measuring nanogram to picogram quantities of volatile metals in small amounts of sample (about 2 µl needed for analysis). The loop and sheathing device are described.

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