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

Abstract

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 HNO(3)/HCl/HF/H(2)O(2) 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 > or = 18 of 31 elements analyzed on a small section of QF substrate are < or = 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.

Size-Differentiated Chemical Composition of Re-Suspended Soil Dust from the Desert Southwest United States

“…Following gravimetric analysis, the Teflon filter was microwave-digested using an acid mixture according to the method of Upadhyay et al (2009) and Clements et al (2012). The extract was then analyzed for 63 elements by highresolution inductively coupled plasma mass spectrometry (ICP-MS) (ThermoFinnigan ELEMENT 2) using an internal indium standard.…”

Characterization of summertime coarse particulate matter in the Desert Southwest—Arizona, USA

“…Following gravimetric analysis, the second set of Teflon filters were analyzed for 63 trace elements (including, but not limited to, Al, As, Ba, Ca, Cd, Co, Cr, Cu, Fe, K, Mg, Mn, Mo, Na, Ni, P, Pb, Rb, Sb, Se, Sn, Ti, U, V, Zn) using highresolution inductively coupled plasma mass spectrometry (HR-ICP-MS, herein referred to as ICP-MS) (ThermoFinnigan, ELEMENT 2; San Jose, CA). Samples were microwave-digested in 30-mL Teflon vials using an acid mixture of 4 mL nitric acid, 0.9 mL hydrochloric acid, and 0.1 mL hydrofluoric acid (Fisher Scientific; Hampton, NH) (Upadhyay et al, 2009). The temperature profile included a 6-min temperature ramp to 140°C, held for 2 min, followed by a 5-min temperature ramp to 165°C, held for 6 min.…”

Chemical Speciation of PM2.5 and PM10 in South Phoenix, AZ

“…Filter digestion and preparation for elemental analysis are similar to methods reported for the digestion of QFFs, 20 except that smaller acid volumes have been used. Briefly, the PM samples were digested in a mixture of 4 mL HNO 3, 0.9 mL HCl, and 0.1 mL HF using a temperatureprogrammable microwave oven with the following temperature program: 6-min ramp to 140°C and held for 2 min, temperature increased to 165°C in 5 min and held for 6 min, and temperature increased to 180°C and held for 15 min.…”

“…Details of instrument settings and analytical parameters (resolutions, calibration, instrument detection limits) can be found elsewhere. 20 NIST SRM 1640 (river water) was analyzed after each 12 samples to monitor drift in instrument response. Propagated analytical uncertainties for elements were determined from the square root of the square of the standard deviation (SD) for filter blanks (n ϭ 4) and the square of SD of ambient samples.…”