Indirect bioluminescent determination of europium(III) using flow injection analysis and on-line reduction

Europium(III) is determined in a flow system based on the reduction of flavin mononucleotide, FMN, by Eu(II) followed by bacterial bioluminescence. Using flow injection analysis, Eu(III) is first reduced to Eu(II) in a zinc amalgam mini-column. The Eu(II) then reduces FMN to FMNH2 and the bioluminescence produced on aerial oxidation of FMNH2 in the presence of alkanal mono-oxygenase (FMN linked), EC 1.14.14.3, and n-decanal is used to determine the Eu(II). Calibration is achieved for 5 × 10−7 to 1 × 10−4 M Eu(III) with a limit of detection (3 s.d.) of 5 × 10−7 M and an analysis rate of 60 h−1. The effects of possible interferences are reported.