Isobutane chemical ionization mass spectra of volatile lanthanide chelates

The separation and analysis of the lanthanide elements pose many problems because of their similar chemical and physical properties. Among the various procedures which have been used to separate and purify these elements are fractional crystallization, liquid-liquid extraction, and ion exchange. All these procedures are extremely complicated. Classical chemical techniques for the qualitative and quantitative analysis of the lanthanides are even more difficult because of their chemical similarity. Emission, absorption, and fluorescent measurements in the X-ray, ultraviolet, or visible region of the electromagnetic spectrum are all very complicated, and often it is found that many of the lines and bands of the lanthanides overlap each other. This overlapping of peaks makes selective identification very difficult and often impossible. Also, these metals form stable diatomic monoxide molecules in flames (refractory oxides), a fact which makes analytical flame spectrometric methods almost impossible.