Multi-element analysis by inductively coupled plasma optical emission spectrometry of airborne particulate matter collected with a low-pressure cascade impactor

A method was developed for the elemental analysis of size segregated partic les ranging from 0.03 to 10 mu m. Sampling and analysis problems are discus sed in this paper. Particles were collected with a Dekati low-pressure casc ade impactor. PTFE filters coated with oleic acid were used as substrate. P articles were microwave digested in closed vessels. The optimum digestion m ixture was composed of HNO3 (1 mL), HF (50 mu L) and H2O (1 mL). The optima l power setting and digestion time were studied in order to achieve an effi cient digestion. A ca. 35 min microwave digestion cycle at a 650 W maximum power allowed complete digestion of the samples. Special emphasis was place d on the pressure in the closed vessels to avoid sample losses. Solution sa mples were analysed by inductively coupled plasma optical emission spectrom etry using an ultrasonic nebuliser for 18 elements (Al, Ba, Ca, Cd, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, Pb, S, Sr, Ti, V, Zn). This procedure was tested wi th NIST Standard Reference Material 1648 Urban Particulate. Recoveries for certified elements ranged from 95 to 105% except for Al (90%). The influenc e of cascade impactor materials was investigated with 44 field samples. Str ong artefacts due to contamination were shown for analysis at environmental concentrations of Al, Cr, Mn and Ni.