Abstract:
Based on detailed study of the interference effects encountered at sodium resonance line at 589.0 and that of potassium at 767.5 nm, a method has been developed for the determination of sodium and potassium in standard reference materials (limestones: KH, KH2, KH3, CCH-1, JLs-1; dolomites: DWA-1, JDo-1 and anhydrite AN) containing relatively low levels of alkalis required for very crucial quality control (QC) procedure in steel industries. Samples were digested in two steps: first by using 5 mi of HClO4 (70%) and secondly by a mixture of HF (40%) + HCl (11 mol l(-1)) + H2SO4 (1:1)[10 + + 10 + 5. An excellent agreement with the certified values was achieved using lanthanum (1000 mu g ml(-1)) and rubidium (2000 mu g ml(-1)) for sodium and potassium, respectively, except for potassium in Japanese reference materials JLs-1 and JDo-1 indicating that, more data for them are still required for assigning their certified values. The values for alkalis in the samples using commonly used buffers are also presented The Student's t-test values indicate that at a confidence level of 95-99% there is no statistical difference between the flame atomic absorption spectrometric results and the reference material data.