Derivative spectrophotometric determination of holmium in rare earth mixtures with 2-(diphenylacetyl)indan-1,3-dione and octylphenyl poly(ethyleneglycol) ether

The zero-order and second-order derivative absorption spectra of the system of holmium with 2-(diphenylacetyl) indan-1, 3-dione and octylphenyl poly(ethyleneglycol) ether have been determined by derivative spectrophotometry. The molar absorptivity of absorption spectra and the derivative spectra are calculated respectively. The absorbances at the absorption maxima for the holmium complex are 48.5 (at 450 nm) and 14.5 (at 460 nm) times greater than for the corresponding chloride. The derivative spectra have been used to eliminate the interference of other lanthanides, and the sensitivity is again increased by a factor of about 5. The calibration graph is linear up to 25 g/ml of holmium. The detection limit, obtained from the sensitivity of the calibration graph and for 3S_b (S_b = standard deviation of a blank without holmium,n = 11), was 0.37 g/ml of holmium. The quantification limit (10S_b was 1.2 g/ml. The method has been applied successfully to synthetic and reference samples of rare earths.