Automated WHole AIR Vial / SoRbent TUBE sampLers for Lab & Field USe
VSI Automatic Air Samplers. Automatic air samplers are devices used for collecting air samples from the atmosphere - both from ambient air and experimental Teflon chambers or PMMA respiration chambers used for gas flux measurements. Measuring the gas and volatile composition and/or isotopic signature of air reveals crucial information about water use, carbon balance, greenhouse gas emissions or other pollutants in natural or managed ecosystems or urban environments, and generally plant and/or soil interactions with the atmosphere. To support cost-effective air sampling campaigns in the laboratory and field, we developed the
- VSI AS-100 Whole Air Sampler to automatically sample ambient air into evacuated vacuum tubes, i.e. vials, exetainers, and the
- VSI AS-101 Sorbent Tube Sampler, passing air through diverse sorbent tubes.
Both highly portable air sampling devices originate from a range of research projects ("Iso-Drone") with academic partners and are fully lab tested. See Leitner et al. (2023) (https://doi.org/10.5194/amt-16-513-2023) for details on both VSI air autosamplers adapted to UAVs.
VSI As-100 and AS-101 Air Sampler - Features
The VSI AS-100 Multiple Vial Whole Air Sampler and AS-110 Multiple Sorbent Tube Sampler for laboratory and field use allow sampling from up to 12 vials (20 ml) or sorbent tubes.
- Vial and tube sizes and dimensions are factory adjustable to meet your replication needs and analytical requirements.
- Get more done by independent air sampling at
-
- present times,
- triggered by environmental cues or
- manually.
- Easy to use and highly portable, simply start the unit for routine sampling.
- Can be used almost anywhere - 12 V-operable for field use with batteries (optional).
- Easily retrieve vials and tubes, and load new containers for the next sampling cycle within minutes.
- Collect accurate samples with confidence and prevent sample loss or contamination, and prevent gaps in your collection cycles (e.g. Night, early morning, weekends, etc.)
- Sample ambient air and pollutants or monitor industrial emissions - covering the daily variation.
To take air sampling to "new heights", have a look at our UAV air samplers. They have been modified to be mounted and operated on unmanned aerial vehicles.
VSI AS-100 Whole Air Vial Sampler Lab / Field - Specifications
AS-100 Whole Air Vial Sampler Lab. The VSI AS-100 air sampler is both lab and field operable (12V) for highest versatility in a large range of experimental settings. For example, the whole air sampler system is mountable on (eddy flux) towers, in tree canopies and on the ground (e.g. attached to soil sampling rings). Automatic sampling can be triggered according to a predefined time schedule for 24/7 measurements, or sampling can be triggered remotely - avoiding e.g. contamination by exhaled human breath. With the systems, air samples are stored in 12 pre-evacuated, vacuum vials for later routine analyses of gas composition (with a gas chromatograph, mass spectrometer). Sample collection from the immediate vicinity occurs via needle puncture through a septum, minimising contamination. Optional, a ventilation system for circulating air over longer distances, thus allowing for several sampling points at distance to the device, can be added. The suitability of the sampling system to measure e.g. isotopic signatures at relevant concentration of CO2 in ambient air samples has been confirmed. Our whole air samplers are easy to use and require minimal training.
An automatic vial evacuator (VSI EV-101) to evacuate/reuse vials (incl. e.g. helium flushing and a strong vacuum pump) is available as option, allowing to easily prepare vacuum tubes both in the lab (220V) and the field (12V).
VSI AS-101 Sorbent Tube Air Sampler Lab / Field - Specifications
AS-101 Sorbent Tube Sampler Lab. At the current configuration, the VSI AS-101 sorbent tube air sampler (weight: c. 1100 g) for laboratory and field measurements (12 V) can be loaded with four sorbent tubes. The sampler can be factory modified to hold at least 12 sorbent tubes (depending on total inflow air required). The sample gas inlet can be set with a manually adjustable pinch valve and adjusted to the sorbent tubes installed (e.g. 50 mL min-1). All tubing is made out of 4 or 6-mm PTFE, and tube connections out of polyethylene terephthalate (PET) or metal. Passing the restriction valve at the sampler inlet, the gas flow is split in two and forwarded to the two inlet ports of an electric four-port gas distribution manifold. The gas manifold enables switching between different sampling modes, either
- loading all (four) or a selection of tubes simultaneously (technical replicates), or
- individually for collecting sequential samples.
The sorbent tubes are fitted to the outlets of the gas manifold using straight push-in fittings. At the outlet of the sorbent tubes, the gas flow is divided into two streams. Each stream then passes through a flow sensor, which records the actual flow rate. Finally, the gas streams are combined and directed to the suction pump. To circumvent the unregulated suction pressure of the pump, a T-piece is installed upstream of the pump inlet to equalise the different flow rates set on the gas inlet restriction valve. This effectively eliminates the exposure to pressure differentials that can lead to altered flow readings, the development of leaks and overuse of sampler components. The AS-101 Sorbent Tube Air Sampler can be fitted with a wide range of different sorbent tubes for different air sampling purposes (see below for sorbents) such as volatile emissions (especially for sesquiterpene and monoterpene sampling), pollen and particulate matter (PM2.5, PM10) concentrations (see below for applications).
The VSI AS-101 Sorbent Tube Sampler for laboratory and field use is equipped with a memory card that records the actual flow rate, temperature, air pressure, humidity, activated sample port number and time over the sampling event. The sampler can be triggered
- Automatically at preset times,
- automatically on the occurrence of specific events (e.g. CO2 concentration, temperature, humidity, location), or
- manually (push button).
The AS-101 is powered by 12V DC and can be fully used in the field (on batteries), and in the laboratory on a 110-230V mains supply. The automatic sorbent tube sampler is easy to use and requires minimal training for achieving accurate sampling.
Application of Automatic Air Samplers
Whole air samplers
-
Automated whole air samplers such as the VSI AS-100 collect air samples from the atmosphere. They are specifically designed
to sample the entire air mass and maintain the integrity of the collected gases in sealed vials for later analysis.
Here are some applications where whole air samplers are useful: Show more -
- Quantitative sampling: Automated whole air samplers are designed to collect air samples in a way that provides accurate and quantitative measurements of gas concentrations. This is achieved by sampling a fixed volume of air over a period of time; replication can ensure that the samples are most representative of the surrounding atmosphere at the time.
- Preservation of gas integrity: The collected air samples are preserved in inert sample container (e.g .glass vials). This ensures that the gas composition is not altered during transport or storage, allowing accurate and reliable analysis. See, however, comments on the Vial Evacuator Website on the potential effects of septa on stored gases.
- Multi-gas analysis: Automated whole air samplers can collect air samples for analysis of multiple gases, including greenhouse gases such as carbon dioxide and methane, and other atmospheric trace gases such as sulphur dioxide, nitrogen oxides and ozone. Isotopes can be successfully discriminated.
- Long-term sampling: Automated whole-air samplers can operate for extended periods of time, allowing air samples to be collected regularly for diurnal or long-term studies of atmospheric composition and changes over time.
- Remote sampling: Some automatic whole air samplers can be operated on UAVs, allowing air samples to be taken from remote locations or at heights of the troposphere usually not accessible.
- Event-triggered sampling: Some whole-air samplers, such as the AS-110, can be fitted to be triggered by environmental cues such as certain temperatures or CO2 concentrations, rending event-based air sampling campaigns feasible.
Overall, automatic whole air samplers are an important tool for atmospheric research, allowing accurate, quantitative and long-term sampling of multiple gases in a variety of locations. Related applications include climate change and environmental research, air quality monitoring, and atmospheric chemistry studies.
For example, collected whole air samples can be easily analysed with our gas analysers in "injection mode", where the small gas aliquot to be analysed is injected into a carrier gas stream with a syringe or similar device for subsequent gas analysis. The example is for CO2.
Sorbent tube Samplers, Sorbent Tube Types and Collection MEdia
-
Automated sorbent tube samplers such as the VSI AS-101 are particularly useful for collecting and analysing volatile organic
compounds (VOCs) and other air pollutants in sorbent traps. Sorbent tubes are widely used in combination with gas chromatographic analytical methods to monitor the vapour phase fraction of
organic compounds in air. Target compounds range in volatility from acetylene and freons to phthalates and PCBs and include apolar, polar and reactive species (Woolfenden, 2010).
Here are some reasons why automated sorbent tube samplers are increasingly being used: Show more -
- High sensitivity: Automated Sorbent Tube Samplers can be fitted with highly sensitive sorbent tubes fitting the sampling task at hand (see below for sorbent tubes) - usually detecting low concentrations of VOCs and other air pollutants. This makes them ideal for use in indoor and outdoor air quality monitoring, and controlled plant experimentation in PTFE reaction chambers.
- Time-integrated sampling: Automatic sorbent tube samplers are designed to collect air samples over a specified period of time, typically a few minutes to some hours or more. This time-integrated sampling provides a representative and accurate measurement of the average concentration of pollutants in the air, while however, particular concentration peaks might be missed during lonegr sampling campaigns.
- Remote sampling: Some sorbent tube samplers can be operated on UAVs, allowing air samples to be taken from remote locations or at unusual heights of the troposphere.
- Maintain sample integrity: The collected substance is trapped on the specific sorbent material inside the sampling tube, preserving sample integrity during transport and storage for reliable and accurate analysis.
Overall, automatic sorbent tube samplers are an important emerging tool for monitoring air quality and investigating indoor and outdoor air pollution. They are highly sensitive, provide time-integrated sampling (of different time periods), preserve sample integrity, and are versatile and easy to use. Automated sorbent tube samplers can be used for a variety of applications, including occupational health and safety assessments, industrial hygiene and indoor air quality investigations, and environmental and plant research. See below for a brief overview on sorbent tubes types supporting different applications.
Sorbent tubes are the most widely used collection media for sampling hazardous gases and vapors in air in research and environmental monitoring settings but also civil and military gas defense strategies. Sorbent Tubes are available from multiple manufacturers incl. CARO Analytical Services, SKC Inc., 7Solutions BV, Uniphos Ltd., SKC Ltd, Zefon International, Sigma-Aldrich/Supelco and Markes International, or can be custom-made by individual laboratories. The sorbent in the tubes can hold various types of sampling media, onto which the volatile substance / contaminant is collected by passing air through the sorbent tubes. The VSI Sorbent Air Sampler AS-101 for laboratory and field use fits most common sorbent tube dimensions (diameter and length) on the market, however, please discuss specific needs (very long tubes, very high flow rates, etc.) with the engineers at Vienna Scientific.
- Sorbent tubes are typically made of glass or metal and contain various types of solid adsorbent material (sorbents). Commonly used sorbents include activated charcoal, silica gel, and organic porous polymers such as Tenax and Amberlite XAD resins. Solid sorbents are selected for sampling specific compounds in air because they: Show more
-
- Trap and retain the compound(s) of interest even in the presence of other compounds,
- Do not alter the compound(s) of interest, and
- Allow collected compounds to be (easily) desorbed or extracted for analysis
Classical sorbent tubes hold e.g. the following material:
- Charcoal Sorbent Tubes. This sorbent has a high surface area for sampling a broad range of primarily non-polar compounds.
- Tenax Sorbent Tubes. Tenax® is a traditional sorbent (porous polymer) for trapping medium to high boiling compounds; it is especially useful for low concentrations because of its low background. Tenax is hydrophobic and is suitable for use in EPA Method TO-17 or IP-1B and other thermal desorption applications. Tenax® GR is a Tenax/graphite composite which extends the range of Tenax to lower boiling compounds. It retains the ability of Tenax to be cleaned easily to a very low background and is similarly used widely for thermal desorption.
- Silica Gel Sorbent Tubes. Silica gel is a adsorbent material of choice for sampling polar hydrocarbons, low molecular weight mercaptans, methanol, amines, and inorganic acids. Treated Silica gel tubes are also used, e.g. 2, 4-dinitrophenylhydrazine for aldehyde sampling, sulphuric acid treated for ammonia.
- Chromosorb Sorbent Tubes. Chromosorb® is a porous polymer sorbent and can be used to trap low-boiling hydrocarbons, benzene, labile compounds, and volatile oxygenated compounds.
- Polyurethane Foam (PUF) Tubes. Polyurethane Foam (PUF) tubes are often available in low or high volume versions. The PUF tubes can e.g. be used for ambient air sampling of organochlorine pesticides, polychlorinated biphenyls (PCBs), and polycyclic aromatic hydrocarbons (PAHs).
- Thermal Desorption Sorbent Tubes. Single and multiple-bed thermal desorption tubes are filled with on or more sorbents (Tenax, Anasorb etc.) and e.g. used for the determination of sub-ppb VOCs in ambient air. Often thermal desorption tubes are available as purged and unpurged versions by suppliers.
In addition, many other sorbents have been used in sorbent tube samplers, including carbon beads, drying tubes, firebrick sorbent, florisil sorbent, molecular sieve sorbent, oxidiser sorbent, soda lime sorbent, and volatile organic sampling traps. Sorbent tubes are attached to a pump or air sampler with a calibrated flow rate for sample collection. Automatic air samplers, such as the VSI AS-101, for sorbent tubes have the advantage of being able to set up sampling schedules or take technical replicates compared to traditional permanently running pump systems.
| References | Air Sampling and Analysis | OPEN |
Related Products
For air sampling tasks using unmanned aerial vehicles, consider the our UAV-based whole air and tube sampling systems.