Extraction and sensitive spectrophotometric determination of ytterbium with 2-(3,5-dichloro-2-pyridylazo)-5-dimethylaminophenol

The operating conditions for the absorptiometric determination of Yb(III) with the reagent 2-(3,5-dichloro-2-pyridylazo)-5-dimethylaminophenol (3,5-diClDMPAP) by a liquid—liquid extraction technique are presented. The complex yields a molar absorptivity of 1.54 × 10⁵l.mole^?1.cm^?1 (λ_max = 588 nm) and an optimum concentration range of 0.025–1.360n mg/l., at pH = 10. The method developed has been applied to the determination of Yb(III) in synthetic and concrete mixtures.