Interferences in the determination of lithium by flame atomic emission spectrometry with platinum-loop atomizer

Abstract

Although flame atomic emission spectrometry (AES) is the most popular method for the determination of Li, the method is subject to interference from alkaline and alkaline earth elements. The effects of CaOH and SrO emission bands are particularly severe. The use of a Pt-loop atomizer was found to eliminate interference from Ca and Sr, as salts of these elements remained as solid residues on the loop material. High contents of F^–, Cl^–, SO₄^2– and PO₄^3– were found to reduce the Li signal, this was largely due to loss of LiCl in the case of Cl^–, in the case of F^–, SO₄^2– and PO₄^3–, the reduction in the Li signal was due to lithium oxide formation. The accuracy of the Pt-loop technique was shown to be satisfactory in matrices of high Ca and Sr contents. The detection limit obtained with the Pt-loop was at least one order of magnitude better than that of conventional AES. The technique was applied in the determination of Li in several sample types.