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CHARON

CHARON
Real-Time Aerosol Inlet for IONICON PTR-TOFMS

The new CHemical Analysis of aeRosol ON-line (CHARON) particle inlet coupled to IONICON PTR-TOFMS instruments quantitatively detects organic sub-µm particulate matter as well as particulate ammonium and nitrate at single digit ng/m³ mass concentration levels in real-time.

Overview

This revolutionary new inlet enables IONICON PTR-TOFMS series instruments to measure aerosols directly with the most versatile, reliable and proven technology for VOC analysis available on the market: PTR-MS. One single instrument covers VOCs and allows additionally the molecular-level characterization of sub-µm particulate organic matter in real-time:

  • On-line and real-time characterization of non-refractory organic sub-µm particulate matter
  • Low limits of detection allow for laboratory-based and ambient measurements
  • Detect the majority of atmospheric organic carbon with a single instrument
  • An exclusive add-on to selected IONICON PTR-TOFMS series instruments

 

The Method

CHARON PTR-TOFMS is an on-line analytical technique that characterizes the molecular composition of sub-µm organic particles on a chemical composition level at a one-minute time-resolution. The CHARON particle inlet consists of a honeycomb activated charcoal denuder that efficiently adsorbs organic gases and transmits particles, a high-pressure aerodynamic lens system that collimates and extracts sub-µm particles, and a thermo-desorber that evaporates non-refractory organic particulate matter at moderate temperatures of 100-160°C and reduced pressures of a few mbar. 

These organics are subsequently analyzed as gas-phase analytes with one of IONICON’s high-resolution PTR-TOFMS instruments. By coupling the CHARON inlet to a PTR-TOFMS, the VOC inlet remains fully operational. An automated valve system allows for scheduled switching between gas- and particle-phase measurements as well as zeroing of the particle inlet.

CHARON has been developed for commercial release in close cooperation between the University of Innsbruck and IONICON.

Benefits

CHARON PTR-TOFMS is a designated on-line and real-time particle analyzer. There is no need for off-line particle pre-concentration e.g. by collection/desorption on surfaces. Analytical artifacts, which may result by reactions on such collection surfaces or thermal degradation at high desorption temperatures and residence times, are efficiently reduced.
In addition, the CHARON particle inlet significantly extends the range of by PTR-MS measurable compounds from gas-phase volatile and intermediate volatile organics (VOC and IVOC) to particle-phase intermediate, semi and low volatile organic compounds (IVOC, SVOC and LVOC, respectively). Therefore, the PTR-MS technology we use allows for the detection of almost the full range of atmospheric organic carbon with one single instrument. The controlled chemical ionization at reduced pressures and defined reaction energies of a PTR-MS drift tube impede the formation of ionic artifacts (e.g. clusters of organics) that might be falsely attributed. Ionization typically proceeds at collision rates that are well predictable (+/- 30%). Fragmentation due to ionization is typically low; between 60% - 100% of the organic mass concentrations can be directly calculated without the need of any additional corrections.
With its high temporal resolution and the high degree of conserved chemical composition information, CHARON PTR-TOFMS is thus the perfect analytical technique to identify and quantitatively follow atmospheric particulate tracer compounds like levoglucosan and polycyclic aromatic hydrocarbons. One-minute resolved data of hundreds of identified chemical compositions boost the quality of source apportionment (e.g. by positive matrix factorization; PMF) to an unseen level. 

Application Example

A morning hour urban air-pollution event was measured in April 2017 in Innsbruck, Austria, and serves as an excellent example for the unique analytical performance of CHARON PTR-TOFMS. Cold temperatures and a strong inversion led to a quick accumulation of primary particulate matter emitted from traffic and domestic heating. Good temporal agreements with in parallel Scanning Mobility Particle Sizer (SMPS) measurements are achieved. The chemical finger-print includes the dominant biomass burning tracer levoglucosan, traffic markers including condensed polycyclic aromatic hydrocarbons (PAHs) and series of potential aliphatic hydrocarbons, the main constituents of lubricant oils.

benefits
Specifications

The CHARON particle inlet is available as an exclusive add-on for selected IONICON PTR-TOFMS series instruments and best combined with the new PTR-TOF 6000 X2, for an ultimate performance experience, high mass resolving power and utmost detection sensitivity. Sensitivities and limits of detection depend on the performance of the applied instrument. Following specifications are typical for CHARON PTR-TOF 8000 series instruments.

CHARON inlet air flow:

~ 500 ml/min

Gas phase denuder
   VOC adsorption:
   Particle transmission:

 
> 99.999% (at ambient concentrations)
> 90% for 80 nm < DP < 1000 nm

Particle enrichment factor:

> 40 for DP = 150 – 1000 nm
reduced for 60 nm < DP < 150 nm

Temperature range:

100 – 160°C

Volatility range: complete evaporation of IVOCs, SVOCs, LVOCs
reduced response for ELVOCs
Response time: single seconds (IVOCs, ammonium)
single minutes (LVOCs)
Limit of detection: 1 - 5 ng/m³ (1 min integration, m/z ~ 200)

Accuracy:

< -10%/+40% (typical ambient mixture)

Power consumption: < 300 W

 

Specifications are subject to change without prior notice.

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