Complexes of lanthanide with Mordant Red 19 are shown to be adsorbed and can be electrochemically reduced at mercury electrode at more negative potential than where MR19 is reduced. Using these properties, an analytical application for the determination of lanthanides is demonstrated by linear sweep voltammetry and by highly sensitive adsorptive stripping analysis. The detection limit of several lanthanides is determined to be about 5.0x10^-10 M with an accumulation time of 5 min, the range of linear response is from 5.0x10^-8 M to 1.0x10^-6 M when optimum conditions are employed. A typical relative standard deviation is found to be 5.2% at 5.0x10^-8 M. The difference in peak potential between complex and MR19 increases with increasing the atomic number of lanthanide ion, which implies a simultaneous analysis of some mixture of lanthanides is possible.

Keywords: Mordant Red 19, Adsorptive stripping analysis, Lanthanide