Studies on derivative fluorimetry. Part I. Determination of trace amounts of samarium, europium and terbium

A method is described for the derivative spectrofluorimetric determination of trace amounts of Sm, Eu and Tb as their ternary complexes with 2-thenoyltrifluoroacetone and diphenylguanidine. These ternary complexes show excitation bands at 345 nm for Sm and Eu and 350 nm for Tb, and fluorescence bands at 645 nm for Sm, 614 nm for Eu and 545 nm for Tb. A mixture of Sm, Eu and Tb can be determined by second-derivative spectrofluorimetry. The calibration graphs are linear over the range 10–100 p.p.m. for Sm, 0.5–50 p.p.m. for Eu and 100–1000 p.p.m. for Tb.