A highly selective fluorescent probe for the determination of Se(IV) in multivitamin tablets

An inducible fluorescent ligand 2-(2-(2-aminoethylamino)ethyl)-3′, 6′-bis(ethylamino)-2′,7′-dimethylspiro[isoindoline-1, 9′-xanthen]-3-one was synthesized and used as a fluorescent probe to detect Se(IV). Se(IV) induced the structural transformation of the fluorescent ligand, resulting in a sharp fluorescence emission in an ethanol system. The fluorescence intensity observed was directly proportional to the concentration of Se ions. The detection limit of Se(IV) was 2.8 × 10^-9 mol L^-1 under optimized conditions. The Se(IV) concentrations in four multivitamins were determined, and have obtained a tiny deviation of 2% compared with the result detected by ICP-AES. The recovery of Se(IV) in four samples ranged from 98% to 103%.