Emerging application of a structural and chemical analyzer for the complete characterization of metal-rich particulate matter

Abstract

Clean air is considered to be a basic requirement of human health and well-being. An increasing range of adverse health effects has been linked to air pollution, at ever-lower concentrations. This research shows the newly developed Structural and Chemical Analyzer (SCA) to be a successful combination of Raman spectroscopy and scanning electron microscope-energy dispersive X-rays that opens up new insight into the composition of particulate matter (PM). The results obtained with soil and lichen samples demonstrate the capability of the technique to obtain elemental and molecular information of every single atmospheric PM focused at the micrometer and submicrometer levels. The SCA approach permitted the individual PM analysis, allowing the identification of the molecular (most commonly as sulphides, sulphates, carbonates, or oxides) form in which several hazardous metals (Zn, Pb, Cu, etc.) are evolved into potentially inhalable PM. During the present research, the synchronization of both techniques at a time revealed the morphological, elemental, and molecular forms of metal-rich PM, avoiding some analysis precautions and making the sample preparation and measurement steps more dynamic. In addition, the thermodynamic simulations carried out with the information obtained were helpful to differentiate whether the PM may be retained in the alveoli (i.e., galena) or if it may be dissolved and pass into the bloodstream (i.e., plattnerite).