Preprints
https://doi.org/10.5194/amt-2021-72
https://doi.org/10.5194/amt-2021-72

  09 Mar 2021

09 Mar 2021

Review status: this preprint is currently under review for the journal AMT.

A Method for Liquid Spectrophotometric Measurement of Various Forms of Iron and Copper in Ambient Aerosols

Yuhan Yang1, Dong Gao2, and Rodney J. Weber1 Yuhan Yang et al.
  • 1Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, 30331, USA
  • 2Department of Environmental Health Sciences, School of Public Health, Yale University, New Haven, 06510, USA

Abstract. Determination of transition metals in ambient aerosols is important due to their toxicity to human health. However, the traditional measurement techniques for metal analysis are often costly and require sophisticated instruments. In this study, we developed and verified relatively low-cost liquid spectrophotometric methods for the measurements of iron (Fe) and copper (Cu), often the two most abundant transition metals in ambient fine particulate matter (PM2.5). For Fe analysis, we utilized a ferrozine based colorimetric method, which has been frequently used for water-soluble (WS) Fe determination, and further extended this approach for the measurement of total Fe (water-soluble + water-insoluble). In this method, Fe is quantified through the formation of a light-absorbing ferrozine-Fe(II) complex (absorbance at 562 nm). A similar colorimetric method, which forms a bathocuproine-Cu(I) complex absorbing light at 484 nm, was developed and examined for measurement of WS and total Cu. These methods were applied to 24-hour integrated filter samples collected in urban Atlanta. Based on PM2.5 ambient aerosols, total and water-soluble Fe and Cu concentrations were in good agreement with inductively coupled plasma mass spectrometry (ICP-MS) measurements (slopes 1.0 ± 0.1, r2 > 0.89). The water-soluble components, operationally defined as those species in the aqueous filter extract that pass through a 0.45 µm pore filter, were further characterized by ultrafiltration, which showed that roughly 85 % of both the Fe and Cu in the water-soluble fraction was composed of components smaller than nominally 4 nm.

Yuhan Yang et al.

Status: open (until 05 May 2021)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on amt-2021-72', Anonymous Referee #1, 06 Apr 2021 reply
  • RC2: 'Comment on amt-2021-72', Anonymous Referee #2, 14 Apr 2021 reply

Yuhan Yang et al.

Yuhan Yang et al.

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Short summary
Iron and copper are commonly found in ambient aerosols and have been linked to adverse health effects. We describe a relatively simple bench-top instrument that can be used to quantify these metals in aqueous solutions and verify the method by comparison with inductively coupled plasma mass spectrometry. The approach is based on forming light absorbing metal-ligand complexes that can be measured with high sensitivity utilizing a long-path liquid waveguide capillary cell.