Wall-stabilised plasma arc applied to the determination of rare earth elements in phosphate samples

Abstract

A wall-stabilised plasma arc seeded with potassium chloride has been used as an excitation source for the spectrographic determination of rare earth elements in samples of phosphate deposits. The samples were treated with a mixture of HNO₃ and HF in a Teflon decomposition vessel and then with H₂SO₄. The effect of the sample matrix on the excitation temperatures in the plasma and on the analytical curves obtained was studied. The results from the analysis of 12 samples, collected from the Abu Tartur plateau, Western Desert, Egypt, are given. The normalised rare earth patterns reveal a marine environment for deposition.