Study of the fluorescence of the lead-morin system in the presence of non-ionic surfactants

Abstract

A study of the fluorescence of the Pb-morin system in the presence of the non-ionic surfactant Genapol PF-20 (ethylene oxide-propylene oxide condensate) has been made. The weak fluorescence of the Pb-morin system is enhanced about nine-fold, at a pH of 3.3 ± 0.2 with a surfactant concentration of 2%. The presence of a non-ionic surfactant also gives greater stability, the system being stable for at least 3 h. The excitation maximum occurs at 420 nm with fluoresence occurring at 495 nm.

The fluorescence is linear up to 1 µg ml^–1 of Pb, and the detection limit is found to be 0.06 µg ml^–1. The precision at 1 p.p.m. of Pb(II) is ±0.47%. Al(III), Be(II), Zn(II) and Sn(II) strongly increase the fluorescence, probably owing to the formation of fluorescent complexes with morin, which are highly sensitised by the surfactant used, and F^–, Fe(III) and Cu(II) decrease the fluorescence signal.