Methodology to Create Reproducible Validation/Reference Materials for Comparison of Filter-Based Measurements of Carbonaceous Aerosols That Measure BC, BrC, EC, OC, and TC

Abstract

A simple method that reproducibly creates validation/reference materials for comparison of methods that measure the carbonaceous content of atmospheric particulate matter deposited on filter media at concentrations relevant to atmospheric levels has been developed and evaluated. Commonly used methods to determine the major carbonaceous components of particles collected on filters include optical attenuation for “Black” (BC) and “Brown” (BrC) carbon, thermal-optical analysis (TOA) for “Elemental” (EC) and “Organic” (OC) carbon, and total combustion for “Total” carbon (TC). The new method uses a commercial inkjet printer to deposit ink containing both organic and inorganic components onto filter substrates at programmable print densities (print levels, as specified by the printer–software combination). A variety of filter media were evaluated. The optical attenuation (ATN) of the deposited sample was determined at 880 nm and 370 nm. Reproducibility or precision (as standard deviation or in percent as coefficient of variation) in ATN for Teflon-coated glass-fiber, Teflon, and cellulose substrates was better than 5%. Reproducibility for other substrates was better than 15%. EC and OC measured on quartz-fiber filters (QFF) compared to ATN measured at 880 nm and 370 nm on either QFF or Teflon-coated glass-fiber yielded R2 > 0.92 and >0.97, respectively. Four independent laboratories participated in a round robin study together with the reference laboratory. The propagated standard deviation among the five groups across all print levels was <2.2 ATN at 880 nm and <2.7 ATN at 370 nm with a coefficient of variation of <2% at ~100 ATN.

Atomic spectrometry update – a review of advances in environmental analysis

“…New multielement RMs for XRFS analysis were prepared 21 by re-aerosolisation onto PTFE filters of small quantities (0.5 and 5.5 mg) of either NIST SRM 2583 (trace elements in indoor air (nominal mass fraction of 90 mg kg −1 Pb)) or NIST SRM 2584 (trace elements in indoor air (nominal mass fraction of 1% Pb)). A procedure for preparing filter-based RMs for the measurement of both black carbon and brown carbon by optical techniques and for measuring OC and TC fractions by combustion techniques involved 22 a novel approach in which a commercially available inkjet printer was used to print ink containing organic and inorganic components onto filter media at programmable print densities. In order to address the lack of RMs for studies using the oxygen-isotope mass-independent fractionation signal, a useful metric for probing the pathways of atmospheric sulfates, purified O 3 was reacted 23 with sodium sulfite to produce three 17 O-enriched sulfate candidate RMs that were analysed using a pyrolysis method calibrated using USGS RM 35 (nitrogen and oxygen isotopes in sodium nitrate).…”