Link to article: https://pubs.acs.org/doi/10.1021/acsestair.3c00073

ABSTRACT:

Decamethylcyclopentasiloxane (D₅), a common ingredient in many personal care products (PCPs), undergoes oxidation in the atmosphere, leading to the formation of secondary organic aerosol (SOA). Yet, the specific contributions of D₅-derived SOA on ambient fine particulate matter (PM_2.5) have not been characterized. This study addresses this knowledge gap by introducing a new analytical method to advance the molecular characterization of oxidized D₅ and its detection in ambient aerosol. The newly developed reversed phase liquid chromatography method, in conjunction with high-resolution mass spectrometry, separates and detects D₅ oxidation products, enabling new insights into their molecular and isomeric composition. Application of this method to laboratory-generated SOA and urban PM_2.5 in New York City expands the number of D₅ oxidation products observed in ambient aerosol and informs a list of molecular candidates to track D₅-derived SOA in the atmosphere. An oxidation series was observed in which one or more methyl groups in D₅ (C₁₀H₃₀O₅Si₅) is replaced by a hydroxyl group, which indicates the presence of multistep oxidation products in ambient PM_2.5. Because of their specificity to PCPs and demonstrated detectability in ambient PM_2.5, several oxidation products are proposed as molecular tracers for D₅-derived SOA and may prove useful in assessing the impact of PCPs-derived SOA in the atmosphere.

CITATION:

Meepage, J. N.;  Welker, J. K.;  Meyer, C. M.;  Mohammadi, S.;  Stanier, C. O.; Stone, E. A., Advances in the Separation and Detection of Secondary Organic Aerosol Produced by Decamethylcyclopentasiloxane (D5) in Laboratory-Generated and Ambient Aerosol. ACS ES&T Air 2024. https://doi.org/10.1021/acsestair.3c00073