Easy-VOC™: Simple, catch-all sampling solution for VOCs in air or gas.

Vapour-phase organics such as ambient air toxics, soil gas contaminants or fugitive industrial emissions can be monitored using a variety of techniques and sampling media. Bags, canisters, sorbent tubes and passive samplers have all been used for many years. Each air sampling option has its own inherent advantages and disadvantages.

 

 

In challenging field conditions sometimes the simplest grab sampling methods are the most suitable. Grab sampling involves collecting volumes of air or gas instantly or over a very short period of time, without pumps or complicated mass flow control equipment. Originally this was only possible using canisters, but canisters are a cumbersome and expensive monitoring option and are only compatible with compounds over a limited volatility range, typically C2 to n-C8/9. Sorbent tubes are compatible with a much wider range of compounds including volatiles from n-C3, semi-volatiles to n-C32 and above (including phthalates, PAHs and PCBs) plus many polar and reactive species.

Accurate & reproducible sampling volumes

Easy-VOC facilitates the rapid, "grab" sample collection of a small volumes (<500 mL) of air/gas directly onto sorbent tubes without the need for calibrated pumps. The relatively small sample volumes accommodate sample concentrations above 1 ppb using conventional GC/MS technology, or down to 10 ppt concentrations using GC/TOF MS with BenchTOF-dx™ from ALMSCO International.

 

Using Easy-VOC also reduces risk of analyte breakthrough, extends the application range of sorbent tubes to even more volatile compounds and minimises water management issues.

Comprehensive and flexible kit options

Every Easy-VOC kit comprises a simple high performance hand pump and 10 industry-standard (3.5" L x ¼" O.D.) conditioned & capped sorbent tubes. A number of standard sorbent combinations are available e.g. for TO-17 air toxics or for soil gas/vapour-intrusion studies. Off-the-shelf packages comprise standard stainless steel or Silcosteel® tubes with long term screw caps or Markes’ SafeLok™ tubes with convenient push-on caps.

 

Patented SafeLok tubes conform to industry standard dimensions and comply with all the requirements of US EPA Method TO-17 but incorporate diffusion locking inserts at either end to prevent sample losses and minimise contamination.

 

Markes supplies the world’s most comprehensive range of thermal desorption tubes and accessories. Easy-VOC kits complement this range and can also be ordered with any Markes tubes. Additional options include: glass tubes, custom sorbent packing, different tube dimensions, RFID electronic tube label (TubeTAG™), 2D barcoding and tube banding. All Markes sorbent tubes are labelled with a unique number.

Easy-VOC Specifications

  • Versatility in sample volumes; min 50 mL, increasing in either 50 mL or 100 mL increments.
  • Flow rates in the range of 100 mL/min to 400 mL/min for quick (grab) sample collection.
  • Intrinsically safe.
  • Intuitive operation.
  • Robust.
  • Reproducible.

Questions & Answers

1. Is there a calibrated pump in Easy-VOC?

 

There is no need to calibrate the Easy-VOC. It simply takes a known volume through the sample tube. This distinguishes it from other pumps that provide a flow through the tube and therefore need to be calibrated. The Easy-VOC dispenses with this requirement, by taking highly reproducible sample volumes in either 50 mL or 100 mL increments.

 

 

2. What is the RSD of the sampling using the Easy-VOC?

 

The sampling volume is very accurate, providing 5% RSD or less for most compounds.

 

 

3. Is the Easy-VOC limited to taking 50 mL or 100 mL volumes?

 

The Easy-VOC is flexible, as if you need to take multiples of 50 mL or 100 mL volumes, then you simply take more than one sample in sequence. The optimum volume will vary depending on the concentration of the analyte and the detector that is used, but typically 500 mL is more than enough for a concentration of >1 ppb when using quadrupole MS detectors.

 

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