Ultratrace Osmium, Ruthenium and Lead in airborne particulate matter: peak area as instrumental datum to improve their simultaneous voltammetric determination.

Peak area as instrumental datum for determining the concentration of metals in solution instead of peak height is proposed for the simultaneous voltammetric determination in particulate matter of ultra-trace Os(VIII), Ru(III) and Pb(II), species linked to vehicle emissions. In the case of species present at ultratrace concentration level or having low reversibility degree of the electrodic processes, the employment of peak area, instead of peak current, permits to achieve limits of detection lower even more of one order of magnitude. The method is based on the catalytic current of the Os(VIII)-, Ru(III)- and Pb(II)-bromate system by differential pulse voltammetry. 0.3 mol L-1 acetate buffer pH 4.5 + 6.9x10-2 mol L-1 NaBrO3 + 2.3x10-4 mol L-1 EDTA-Na2 was employed as the supporting electrolyte. For all the elements, the accuracy, expressed as relative error e%, and the precision, expressed as relative standard deviation sr %, were satisfactory being lower than 6%. To better validate the analytical procedure, a comparison with spectroscopic (electrothermal atomic absorption spectroscopy, ET-AAS) is also reported.