NONEXTRACTIVE SPECTROFLUOROMETRIC DETERMINATION OF ALUMINUM IN REAL, ENVIRONMENTAL AND BIOLOGICAL SAMPLES USING CHROMOTROPIC-ACID

An ultra-sensitive and highly selective nonextractive fluorimetric met hod is presented for the rapid determination of aluminium at nano-trac e levels using chromotropic acid as a fluorimetric reagent [lambda(ex) = 360 nm and lambda(em) = 390 nm] in the pH range of 4.1-4.7. The flu orescence intensity of the metal chelate (2:3 complex) reaches a const ant value within 1/2 hr and remains unchanged for over 48 hr. The fluo rescence intensity aluminium concentration calibration curve is collin ear between 1 and 300 ng/ml of Al. A constant fluorescence intensity i s obtained over a wide range (1:50-1:1500) of Al: reagent molar concen trations. Large excesses of over 60 cations, anions and complexing age nts (like tartrate, oxalate, phosphate, thio-urea, SCN-, etc.) do not interfere in the Al determination. The developed method was successful ly used in assaying aluminium in several standard reference materials (Al-bronze, brass, stainless steel) as well as in some environmental a nd biological samples. The method is very precise and accurate (S.D = +/- 0.001 on 10 ng/ml; 11 determinations).