Study of ph and substrate effects on room-temperature phosphorimetry of some indolecarboxylic acids.
Room-temperature phosphorescence (RTP) of eight indolecarboxylic acids has been investigated under different pH conditions, and on several ion-exchange filter papers. RTP excitation and emission wavelengths do not change significantly with pH. The largest RTP signals are obtained from neutral solutions adsorbed on DE-81 anion-exchange filter paper, while alkaline (pH approximately 13) solutions on S & S 903 filter paper treated with DTPA (diethylenetriaminepenta-acetic acid) give stronger signals than neutral or acidic (pH approximately 1.6) solutions on the same substrate. The existence of several hydrogen-bonding interactions between the various ionic indolecarboxylic acid species and the substrates is discussed. Heavy-atom enhancement factors ranging between 4 and 550, according to the compound, are obtained with iodide. Absolute limits of detection between 100 and 500 pg demonstrate the usefulness of RTP for determination of indolecarboxylic acids at the trace level.
Andino
M
M
Department of Chemistry. University of Florida, Gainesville, FL 32611, USA.
Aaron
J J
JJ
Winefordner
J D
JD