Fluoride ion detection by 8-hydroxyquinoline-Zr(IV)-EDTA complex.
A simple fluorescent detection based on the ligand exchange mechanism is proposed for the fluoride ion in aqueous media. This procedure is based on the exchange of 8-hydroxyquinoline (oxine) coordinated to Zr(IV) by fluoride ion without interference from other common anions. The ternary complex of oxine with [Zr(H(2)O)(2)EDTA].2H(2)O formed by replacing two water molecules in aqueous solution provides a sensitive signalling system for fluoride ion in the concentration range from 6 x 10(-7)M to 8 x 10(-4)M. The green fluorescence (lambda(max)=532 nm) exhibited by the complex upon excitation at 247 nm decreases in intensity with fluoride addition with a detection limit of 12 ppb. The complexation reaction between oxine and Zr(IV)-EDTA and the ligand exchange reaction with fluoride ion has been investigated by UV-vis and fluorescence spectroscopies combined with the PM3 semi-empirical quantum chemical calculations. Job's method of continuous variation and the molar ratio method ascertain a 1:1 stoichiometry composition of the chelate in aqueous media.
Sathish
R Sai
RS
Department of Chemistry, Sri Sathya Sai Institute of Higher Learning, Prashanthi Nilayam, Andhra Pradesh 515134, India.
Sujith
U
U
Rao
G Nageswara
GN
Janardhana
C
C
D005459:Fluorides / Q000032:analysis*; D007477:Ions / Q000032:analysis; D009942:Organometallic Compounds / Q000737:chemistry*; D015125:Oxyquinoline / Q000737:chemistry; D011804:Quinolines / Q000737:chemistry*; D013050:Spectrometry, Fluorescence / Q000379:methods*
C517028:8-hydroxyquinoline-Zr(IV)-EDTA; D007477:Ions; D009942:Organometallic Compounds; D011804:Quinolines; D015125:Oxyquinoline; D005459:Fluorides