SELECTIVE SPECTROFLUOROMETRIC DETERMINATION OF LITHIUM(I) WITH QUINIZARIN BY EXTRACTION INTO TRIBUTYL-PHOSPHATE

A method for the determination of trace amounts of lithium at the ppb level has been described based on the reaction of lithium(I) with 1,4- dihydroxyanthraquinone (quinizarin) in alkaline medium, extraction int o tributyl phosphate (TBP) and measurement of the fluorescence of the organic phase. A linear calibration was found in the concentration ran ge of 9-250 ppb of lithium in aqueous solutions (lambda(exe) = 590 nm, lambda(em) = 670 nm) with a RSD of 2.7% for 100 ppb of lithium. After a prior treatment with potassium carbonate the method is highly speci fic for the analysis of lithium in presence of other inorganic ions. T he proposed procedure has been applied for the determination of lithiu m in mineral waters, drugs and vegetables.