Analytical Methods for Determining the Concentration Ratio in Mixtures of Trioctylphosphine Oxide and Di(2-Ethylhexyl)Phosphoric Acid

Abstract

Analytical methods are described for determining the concentration ratio of trioctylphosphine oxide (TOPO) and di(2-ethylhexyl)phosphoric acid (D₂ EHPA) in hydrocarbon solvents or in mixtures where the D₂ EHPA is the solvent. The Electron Spectroscopy for Chemical Analysis (ESCA) method was used to analyze the mixtures for the relative amounts of phosphine oxide-phosphorus to phosphoric acid-phosphorus as well as the variance with the mixture composition of the Ols/P2p signal intensity. The nmr signal strength of the protons of the oxymethylene group of the D₂ EHPA and the signal strength of the other protons of D₂ EHPA and TOPO were measured in solutions of varying concentrations of D₂ EHPA and TOPO. Mass spectral comparisons of the molecular ion strengths of TOPO and D₂ EHPA were also correlated with mixture composition.