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Pure Appl. Chem., 2006, Vol. 78, No. 1, pp. 69-78

Uptake of platinum-group elements with the diet: A preliminary investigation

Chiara Frazzoli, Roberta Cammarone and Sergio Caroli

Istituto Superiore di Sanità, Viale Regina Elena 299, 00161 Rome, Italy

Over the past decade, the increasing use of car catalytic converters based on platinum-group elements (PGEs) has been raising more and more concern. Human exposure to these metals occurs indirectly also through the diet. Thus, a pilot investigation was undertaken in order to ascertain the actual intake of PGEs through bread and cow milk. All manipulations were performed in a Class-100 clean room so as to minimize the risk of sample contamination. Digestion of samples was achieved by means of a mixture of HNO3 and H2O2 with the assistance of microwave irradiation.
Determinations were performed by sector field inductively coupled plasma-mass spectrometry (SF-ICP-MS) to quantify Pd, Pt, and Rh. The isotopes 105Pd+, 103Rh+, and 195Pt+ were used for the quantification. Major interferences were caused by 40Ar65Cu+ on 105Pd+, 179Hf16O+ on 195Pt+, and 87Rb16O+ and 87Sr16O+ on 103Rh+. Both physical and mathematical approaches for the interference correction were used. The mean values for PGEs were found to be as follows (in ng kg-1): full-cream milk: Pd, 3790; Pt, 83.2; Rh, 1680; skim milk: Pd, 12 400; Pt, 83.6; Rh, 1090; wholemeal bread: Pd, 3210; Pt, 171; Rh, 139; white bread: Pd, 27 400; Pt, 257; Rh, 2230. The preliminary data obtained in this study are probative of the significant portion of the total exposure to PGEs, which is due to the diet.