SIMS depth profile analysis of particles collected in an urban environment

Abstract

AbstractAnalytical procedures of collection and sample preparation of micro‐ and nanoparticles from urban environment as well as results of analyses are presented. Particulate matter is collected from indoor and outdoor urban air by several methods using mechanical collectors: personal cascade impactor and quartz filters. The other method treats human organisms as collectors: the method is based on induced sputum. Elemental analysis of the collected material performed by spark‐source mass spectrometry (SSMS) on magnetic sector JEOL JMS‐1BM2 mass analyzer, gives concentration of over 20 elements with ppb sensitivity. SIMS depth profile analysis is performed on SAJW‐05 apparatus with quadrupole QMA‐410 analyzer and Physical Electronics ion gun. Indium substrate covered with particulate matter is scanned with 100 µm diameter 5 keV Ar+ ion beam. Particles collected by cascade impactor were deposited at indium substrates. Four aerodynamic diameter classes were analyzed, i.e. 10–2.5 µm, 2.5–1 µm, 1–0.5 µm and 0.5–0.25 µm. Depth profile analysis was performed up to 100 nm depth of eroded material. Results were obtained on sets of particles, and the measured secondary ion currents gave integral values of the analyzed material. Assuming average surface composition of the analyzed particles some hints on the compositional morphology of the type of ‘core‐shell’ are extracted. Obtained data on the bulk elemental composition and SIMS depth profile results show the dependence on the grain size. Copyright © 2010 John Wiley & Sons, Ltd.