Determination of trace zirconium and hafnium in basaltic rocks by inductively coupled plasma atomic emission spectrometry after chemical separation: an evaluation of two methods based on extraction chromatography

The determination of Zr and Hf in basaltic rocks by inductively coupled plasma atomic emission spectrometry after extraction chromatographic separation is reported. Two different approaches were employed using tricaprylylmethylammonium chloride (Aliquat 336) and N-benzoyl-N-phenylhydroxylamine (BPHA) as stationary phases supported on inert porous polymeric substrates. The major advantages of the separation schemes are simplicity and the easy separation of Zr and Hf from Ti, a major element in rocks. The BPHA approach is superior to the Aliquat 336 approach with regard to sample preparation and separation conditions. The method yields detection limits of 0.02 and 0.07 mu g g(-1) for Zr and Hf, respectively. The analytical results for international reference rock materials (BIR-1, W-2, BHVO-1) showed excellent agreement with literature values obtained by spark source mass spectrometry and inductively coupled plasma mass spectrometry. The relative standard deviations were in the range 2-4% for the samples analysed.