Determination of PM_2.5 Sulfate and Nitrate with a PC-BOSS Designed for Routine Sampling for Semi-Volatile Particulate...

Area of Science:

• Environmental Science
• Analytical Chemistry
• Atmospheric Science

Background:

• Ambient particles contain semi-volatile compounds like ammonium nitrate, prone to loss during filter collection.
• Inaccurate measurements of these species hinder understanding of fine particle health effects.
• Previous samplers (e.g., BOSS) required complex field calibration, limiting routine use.

Purpose of the Study:

• To develop and validate a novel sampler for accurate measurement of semi-volatile fine particulate species.
• To eliminate sampling artifacts associated with ammonium nitrate and semi-volatile organic compounds.
• To enable routine field collection of sequential samples for detailed analysis.

Main Methods:

• A Particle Concentrator-Brigham Young University Organic Sampling System (PC-BOSS) was developed, combining a virtual impactor with a diffusion denuder and multifilter pack.
• The PC-BOSS concentrates particles (0.1-2.5 μm) before denuder and filter collection.
• Sampler validation involved collocated comparisons with established methods (annular denuder, Chem Spec) for PM2.5 sulfate and nitrate.

Main Results:

• The PC-BOSS sampler effectively collects semi-volatile species without significant positive or negative artifacts.
• Validation studies showed PC-BOSS provides accurate results for PM2.5 sulfate and nitrate with ±5-8% precision.
• Traditional samplers exhibited an average 33% loss of PM2.5 nitrate during sampling.

Conclusions:

• The PC-BOSS sampler is a reliable tool for accurate determination of fine particulate nitrate and semi-volatile organic material.
• This advancement facilitates a more complete understanding of health effects linked to fine particle exposure.
• The PC-BOSS addresses limitations of previous methods, enabling routine, artifact-free field sampling.