Fluorimetric determination of titanium with 2-methyl-3-ethyl-5-hydroxychromone

Titanium reacts with 5-hydroxychromone and eleven of its derivatives to form water-insoluble yellow complexes, which exhibit yellow-green fluorescence on extraction into carbon tetrachloride. An investigation of the substituent effect on the fluorescence intensity of the titanium complexes of these reagents showed that the best fluorescent reagent for the determination of titanium is 2-methyl-3-ethyl-5-hydroxychromone. The maximum wavelengths of the excitation and emission spectra of 2-methyl-3-ethyl-5-hydroxychromone complex are 395 nm and 513 nm, respectively. The titanium complex shows constant fluorescence intensity when extracted from a solution of pH 6.5–8.5. When extraction is done with 10ml of carbon tetrachloride, 0.5–5.0 μg of titanium can be determined. The effects of diverse ions and of substituent position in the reagents are discussed.