Time-resolved characterization of particle associated polycyclic aromatic hydrocarbons using a newly-developed sequential spot sampler with automated extraction and analysis

Abstract

A versatile and compact sampling system, the Sequential Spot Sampler (S3) has been developed for pre-concentrated, time-resolved, dry collection of fine and ultrafine particles. Using a temperature-moderated laminar flow water condensation method, ambient particles as small as 6 nm are deposited within a dry, 1-mm diameter spot. Sequential samples are collected on a multiwell plate. Chemical analyses are laboratory-based, but automated. The sample preparation, extraction and chemical analysis steps are all handled through a commercially-available, needle-based autosampler coupled to a liquid chromatography system. This automation is enabled by the small deposition area of the collection. The entire sample is extracted into 50–100μl volume of solvent, providing quantifiable samples with small collected air volumes. A pair of S3 units was deployed in Stockton (CA) from November 2011 to February 2012. PM2.5 samples were collected every 12 hrs, and analyzed for polycyclic aromatic hydrocarbons (PAHs). In parallel, conventional filter samples were collected for 48 hrs and used to assess the new system’s performance. An automated sample preparation and extraction was developed for samples collected using the S3. Collocated data from the two sequential spot samplers were highly correlated for all measured compounds, with a regression slope of 1.1 and r2=0.9 for all measured concentrations. S3/filter ratios for the mean concentration of each individual PAH vary between 0.82 and 1.33, with the larger variability observed for the semivolatile components. Ratio for total PAH concentrations was 1.08. Total PAH concentrations showed similar temporal trend as ambient PM2.5 concentrations. Source apportionment analysis estimated a significant contribution of biomass burning to ambient PAH concentrations during winter.

Heterogeneous Ozonolysis of Endocyclic Unsaturated Organic Aerosol Proxies: Implications for Criegee Intermediate Dynamics and Later-Generation Reactions

“…For both reaction systems, particles with a mean diameter of ∼110 ± 10 nm were generated and the total volume concentrations for the particles were ∼900–1200 μm 3 cm –3 (size distributions shown in Supporting Information, Figure S1). The remaining flow was either pulled by an online thermal desorption time-of-flight chemical ionization mass spectrometer (TD-TOF-CIMS) (Aerodyne Research Inc.) at approximately 2 L min –1 or collected by a sequential spot sampler (Aerosol Devices Inc., SS110) , at 1–1.5 L min –1 for offline analysis. The sampling time for the spot sampler was usually from 30 min to 1 h, depending on the aerosol mass loading in the flow tube reactor.…”

Efficient collection of viable virus aerosol through laminar‐flow, water‐based condensational particle growth

“…), and for capturing aerosols for chemical and toxicological characterization (Eiguren‐Fernandez et al . ,b). However, this study is the first to evaluate its efficiency for virus aerosols.…”

Ozonolysis of α-Pinene and Δ3-Carene Mixtures: Formation of Dimers with Two Precursors

“…The AURA chamber is operated in batch mode, allowing for studies of both the initially formed products as well as the aged products in the particle phase. To avoid artifacts from filter-based aerosol sampling such as adsorption of gases leading to overestimation of the particle component concentrations , and to minimize labor and time consumption, we here use a sequential spot sampler (3S) for aerosol collection. The 3S operates by activating particles with a temperature-moderated water condensation approach and depositing them into wells on a multi-well plate, yielding a concentrated spot of aerosols ready for analysis .…”

“…To avoid artifacts from filter-based aerosol sampling such as adsorption of gases leading to overestimation of the particle component concentrations , and to minimize labor and time consumption, we here use a sequential spot sampler (3S) for aerosol collection. The 3S operates by activating particles with a temperature-moderated water condensation approach and depositing them into wells on a multi-well plate, yielding a concentrated spot of aerosols ready for analysis . In this way, the 3S provides time-resolved filter-free aerosol sampling for offline analysis.…”