R. Escobar et al., DETERMINATION OF TRIVALENT AND HEXAVALENT CHROMIUM IN WASTE-WATER BY FLOW-INJECTION CHEMILUMINESCENCE ANALYSIS, International journal of environmental analytical chemistry, 61(3), 1995, pp. 169-175
Flow injection analysis (FIA) has been applied to the determination of
both Cr(III) and Cr(VI) in waste water. The method is based on the me
asurement of Cr(III)-catalyzed light emission from luminol oxidation b
y hydrogen peroxide and the apparatus consists of a FIA system with a
flow cell suitable for chemiluminescence detection. Cr(III) is determi
ned directly by the chemiluminescence, meanwhile Cr(VI) is reduced pre
viously to Cr(III) by H2O2 in acidic medium and then the total amount
of chromium is determined. The concentration of Cr(VI) is obtained by
the difference between the Cr(III) and Cr(VI) determinations. We have
analyzed synthetic mixtures of both species, Cr(VI) and Cr(III), using
this method and its application to waste water has been shown to be v
ery efficient. The method is simple, inexpensive, sensitive (subnanomo
lar concentrations), selective and rapid. Tens of samples per hour can
be performed with tolerance to potential interferants.