absorption indicator

Definitions of absorption indicator

1. noun

   an indicator used in reactions that involve precipitation
   types:

   fluorescein, fluoresceine, fluorescent dye, resorcinolphthalein

   a yellow dye that is visible even when highly diluted; used as an absorption indicator when silver nitrate solution is added to sodium chloride in order to precipitate silver chloride (turns pink when no chloride ions are left in solution and negative fluorescein ions are then absorbed)

   bromeosin, eosin

   a red fluorescent dye resulting from the action of bromine on fluorescein; used in cosmetics and as a biological stain for studying cell structures

   type of:

   indicator

   (chemistry) a substance that changes color to indicate the presence of some ion or substance; can be used to indicate the completion of a chemical reaction or (in medicine) to test for a particular reaction