Revolutionizing Air Pollution Monitoring with the Vocus Elf


Air pollution is a pressing global issue, and cities are taking steps to monitor and mitigate its impact. In Denver, Colorado, USA a trial run of a Vocus Elf (Proton-Transfer-Reaction) mass spectrometer is being conducted at an Atmospheric Science and Chemistry mEasurement NeTwork (ASCENT) – Aerosol Chemical Speciation Monitor Network air pollution monitoring site. This cutting-edge instrument offers real-time, sensitive VOC (volatile organic compound) measurement capabilities and is expected to play a crucial role in characterizing aerosol chemical composition and physical properties. With its small footprint, power efficiency, and advanced data acquisition features, the Vocus is set to revolutionize air quality monitoring in Denver and beyond.

Aiming to establish a comprehensive, high-time-resolution, long-term measurement network in the United States, ASCENT is funded through the NSF Mid-Scale Research Infrastructure program. This network is dedicated to characterizing aerosol chemical composition and physical properties, which are critical for understanding air pollution sources, formation processes, and their impacts on human health and the environment.

To achieve its goals, ASCENT requires state-of-the-art instrumentation capable of capturing real-time data with high sensitivity and accuracy. The addition of the Vocus Elf at the ASCENT site in Denver aligns perfectly with these objectives. This instrument’s unique features make it an ideal tool for monitoring volatile organic compounds in the atmosphere.

TOFWERK’s Vocus Elf (white instrument with yellow waves) installed with the rest of the instrumentation suite. The ACSM (blue instrument) is also a TOFWERK OEM product developed in partnership with Aerodyne Research.

Key Features of the Vocus

The Vocus Elf offers several key features that make it well suited for air pollution monitoring at the ASCENT site in Denver. Firstly, its small footprint and low power requirement make it easy to integrate into existing monitoring setups without significant modifications. This advantage allows for efficient use of limited space and energy resources, making it an attractive choice for urban monitoring stations.

Secondly, the Vocus Elf provides real-time, sensitive VOC measurements. It utilizes proton-transfer-reaction mass spectrometry (PTR-MS) technology, which enables rapid analysis and detection of a wide range of volatile organic compounds. This capability is crucial for monitoring air quality in real time, providing researchers with instant access to accurate data on pollutant concentrations.

Furthermore, the Vocus Elf boasts automatic data acquisition and processing features. It includes routine automated backgrounds, calibrations, and conversion to finalized parts per billion (ppb) data without the need for additional post-processing. This automation streamlines data analysis, reducing the time and effort required by researchers and ensuring reliable and consistent results.

Lastly, the instrument’s full-spectrum acquisition capability is particularly noteworthy. It allows for source apportionment, enabling scientists to identify specific compounds and trace their origins. This information is invaluable in understanding the sources of air pollution, whether it be traffic-related emissions, industrial processes, or natural sources like vegetation.

End-User Testimonial and Future Implications

“Before leaving the install, there was already clear structure on the data. Clear plumes of toluene and other aromatics, monoterpenes, and secondary products steadily increasing. I think there was a plume of acetonitrile as well. It was just 1 hour, but clearly the instrument is working, and it’ll be a great tool to characterize the air there.”

– ASCENT Atmospheric Scientist

Real-time measurements taken with the Vocus Elf.

One of ASCENT’s atmospheric scientists noted the presence of clear plumes of toluene and other aromatics, likely from traffic emissions, as well as monoterpenes, potentially from marijuana cultivation. Additionally, secondary products like acetaldehyde and acetone were steadily increasing, indicating ongoing chemical reactions in the atmosphere. A potential plume of acetonitrile was also confirmed, further highlighting the instrument’s ability to detect and characterize various VOCs in real time.

These preliminary results demonstrate the Vocus Elf’s reliability and potential as a valuable tool for air quality characterization. By providing detailed insights into the composition of the atmosphere, it empowers researchers to make informed decisions and implement targeted measures to improve air quality.

Looking ahead, the deployment of the Vocus Elf at the ASCENT site in Denver holds great promise for future air pollution studies. The instrument’s ability to continuously monitor VOCs with high sensitivity and accuracy opens possibilities for comprehensive and long-term data collection. This data will allow scientists to track changes in air quality over time, identify pollution hotspots, and evaluate the effectiveness of pollution control measures.