title: Direct determination of uranium in seawater by laser fluorimetry.
abstract: A method for estimation of uranium in seawater by using steady state laser flourimetry is described. Uranium present in seawater, in concentration of approximately 3 ng ml(-1) was estimated without prior separation of matrix. Quenching effect of major ions (Cl(-), Na(+), SO(4)(-), Mg(+), Ca(+), K(+), HCO(3)(-), Br(-)) present in seawater on fluorescence intensity of uranium was studied. The concentration of phosphoric acid required for maximum enhancement of fluorescence intensity was optimized and was found to be 5%. Similarly the volume of concentrated nitric acid required to eliminate the quenching effect of chloride and bromide completely from 5 ml of seawater were optimized and was found to be 3 ml. A simple equation was derived using steady state fluorescence correction method and was used for calculation of uranium concentration in seawater samples. The method has a precesion of 1% (1s, n=3). The values obtained from laser fluorimetry were validated by analyzing the same samples by linear sweep adsorptive stripping voltametry (LSASV) of the uranium-chloranilic acid (2,5-dichloro-3,6-dihydroxy-1,4-benzoquinone) complex. Both the values are well in agreement.
authors.affiliation: Analytical Chemistry Division, Bhabha Atomic Research Centre, Mumbai 400085, India. sanjukta k@rediffmail.com
authors.forename: Sanjukta A
authors.initials: SA
authors.lastname: Kumar
authors.forename: Niyoti S
authors.initials: NS
authors.lastname: Shenoy
authors.forename: Shailaja
authors.initials: S
authors.lastname: Pandey
authors.forename: Suvarna
authors.initials: S
authors.lastname: Sounderajan
authors.forename: G
authors.initials: G
authors.lastname: Venkateswaran
mesh_terms: D001965:Bromides / Q000302:isolation & purification; D002712:Chlorides / Q000302:isolation & purification; D005470:Fluorometry / Q000295:instrumentation* / Q000379:methods*; D007477:Ions / Q000737:chemistry; D007834:Lasers; D017942:Nitric Acid; D012623:Seawater / Q000737:chemistry*; D014501:Uranium / Q000032:analysis* / Q000737:chemistry
chemical_list: D001965:Bromides; D002712:Chlorides; D007477:Ions; D017942:Nitric Acid; D014501:Uranium