Performance of Small Evacuated Canisters Equipped with a Novel Flow Controller for the Collection of Personal Air Samples

Abstract

Small evacuated canisters have become more common in industrial hygiene personal sampling in recent years. The smaller canisters necessitate a low flow rate to ensure a full-shift air sample can be collected. Evaluation of small evacuated canisters compared to sorbent sampling methods is essential to ensure that the canisters accurately monitor airborne contamination. This data, in a controlled environment, will provide practitioners with valuable reference information when considering air-sampling campaigns. Six 300-mL evacuated canisters were used to collect 6-hour breathing zone samples of styrene on volunteers in a large exposure chamber. The canisters were specially designed with a capillary flow controller developed at McGill University in the mid-1990s. Based on the geometry of the capillary the airflow into the canisters was controlled to a low flow rate, ∼ 0.3 mL/min. This low sampling flow rate allowed for the use of small-volume canisters as personal samplers to collect styrene vapors. Charcoal tubes and diffusive badges were simultaneously used to collect side-by-side samples for comparison. In addition, an online gas chromatograph (GC) documented the concentration in the chamber throughout the duration of the exposure. The three methods did not disclose any significant statistical difference when compared to the online GC values and to each other. In addition, linear regression analysis between the charcoal tubes and the canisters resulted in a correlation (R² > 0.95). An evaluation of the bias and precision (overall uncertainty) of the capillary-canister method, charcoal tubes, and diffusive badges found them to be within criteria established by European Committee for Standardization 482. The results indicate that the capillary-canister sampling device can be an acceptable alternative to sorbent samplers as a personal sampler providing reliable results that are representative of exposures.

Keywords:

• air sampling
• evacuated canisters
• volatile organic compounds

ACKNOWLEDGMENTS

We would like to thank Ginette Charest Tardif for the GC analysis and Ross Thuot for coordinating the air sampling. In addition, we thank the volunteers who donated their time to this project. Also, our gratitude to the Institut de Recherche Robert-Sauvé en Santé et en Sécurité du Travail (IRRST) whose grants funded this research.

Notes

^A Peak concentrations were generated at 11:00 a.m., 12:15 p.m., 1:30 p.m., and 2:45 p.m.

^A GC Reference is the average concentration measured during the six hour sampling period from n = 60 measurements.

^B n = 5 for each test.

^C TLV = 85.2 mg/m³ (20 ppm).