Evaluation of polyurethane foam, polypropylene, quartz fiber, and cellulose substrates for multi-element analysis of atmospheric particulate matter by ICP-MS

Traditional methods for the analysis of trace metals require particulate matter (PM) collected on specific filter substrates. In this paper, methods for elemental analysis of PM collected on substrates commonly used for organic analysis in air quality studies are developed. Polyurethane foam (PUF), polypropylene (PP), and quartz fiber (QF) substrates were first digested in a mixture of HNO3/HCl/HF/H2O2 using a microwave digestion system and then analyzed for elements by inductively coupled plasma mass spectrometry. Filter blanks and recoveries for standard reference materials (SRMs) on these substrates were compared with a cellulose (CL) substrate, more commonly used for trace metal analysis in PM. The results show concentrations of filter blanks in the order of QF > PUF > PP > CL with a high variability in PUF and PP blanks relative to QF. Percent recovery of most elements from the SRMs on all substrates are within ±20% of certified or reference values. QF substrates showed consistent blanks with a reproducibility better than ±10% for the majority of elements. Therefore, QF substrates were applied to ambient PM collected in a variety of environments from pristine to polluted. Concentrations of field blanks for ≥18 of 31 elements analyzed on a small section of QF substrate are ≤25% of the amounts present in samples for urban atmospheres. Results suggest that QF used in a high-volume sampler can be a suitable substrate to quantify trace elements, in addition to organic species and hence reduce logistics and costs in air pollution studies.