Investigation of HfO+ interference in the determination of platinum in a catalytic converter (cordierite) by inductively coupled plasma mass spectrometry

The determination of Pt in cordierite is subject to strong interference by spectral overlap from HfO+ ions with all Pt isotopes. Two mathematical correction methods based on the HfO+Hf+ ratio and a method for the chemical separation of Hf based on adsorption chromatography and isotope dilution were investigated to correct for this interference. Flow infection was used to prevent clogging of the cone orifice. To enhance the sensitivity and thus lower the detection limit, thermospray nebulization was used for sample introduction and the method was compared with pneumatic nebulization. In addition, the memory effects were evaluated for both systems. Analysis of artificial solutions (1 ng Pt ml(-1)) yielded results within 3% of the true value. The Pt content (ca. 50 ng g(-1)) of a cordierite sample, previously exposed to exhaust gases, could be determined with precisions of about 10-25% and the results agreed with earlier determinations by other workers.