adsorption indicator

adsorption indicator

[ad′sȯrp·shən ‚in·də‚kād·ər]
(analytical chemistry)
An indicator used in solutions to detect slight excess of a substance or ion; precipitate becomes colored when the indicator is adsorbed. An example is fluorescein.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.