Why use EPA Method
TO-14/TO-15 for Air
Sampling?
Background:
- TO-14 is the original and most common name for a method used to test ambient air for Toxic Organic Compounds. An improved method is TO-14a, and the newest is TO-15. The analytical method used at KAR Laboratories is TO-15 "Determination of Volatile Organic Compounds (VOCs) in Air Collected In Specially-Prepared Canisters And Analyzed by Gas Chromatography/Mass Spectrometry (GC/MS)" - EPA Compendium Method TO-15, Second Edition. January, 1999.
- Summa Canisters, six liter in volume, are used most commonly for ambient air samples and for collecting samples over time. KAR has over 75 in inventory. A Summa canister is a stainless steel vessel in which the internal surfaces have been specially passivated using the "Summa process". This process uses an electro-polishing step followed by chemical deactivation to produce a surface that is very chemically inert. A canister will hold a high vacuum (>28" Hg) for up to 30 days. After this, low level concentrations of VOCs may appear as contaminants. For this reason, we store our canisters pre-cleaned using proprietary techniques and certified using GC/MS TO-15 protocols, then stored with pressurized ultra-clean nitrogen gas. When a canister is ordered for use, our laboratory readies it by evacuating the canister using the combination of a mechanical fore-pump in conjunction with a turbomolecular vacuum pump. Sorry, but even if the canister is returned unused, the normal per-sample charge will apply because we must go through the entire pre-screen/analysis/cleanout/recertification process to ensure the readiness of the container for the next use.
- Analytes. Unlike Tedlar bags or Adsorptive Tubes, TO-14/15 covers the widest range of volatile organic compounds. We are calibrated for and report the original 40-compound TO-14 analyte list. The newer TO-15 method mentions suitability for a whopping 97 analytes that can be analyzed, but it is very rare (and very expensive!) to be fully calibrated and analyze for all 97 analytes. The most cost-effective approach for the widest range of compounds is to request the TO-14 analyte list along with "Tentatively Identified Compounds" (TICs) if they are detected in the test. Click here for the TO-14 parameter list.
- By far the easiest sampling protocol. No stopwatches, no evacuation chambers, no calibrated sampling pumps, no failing pump batteries, no fragile glass tubes, no hazardous impinger solutions, and no danger of hooking up the sampling train incorrectly. For a grab sample, just open the valve on the vacuum canister, let it fill up, then close valve.
- Samples can also be collected over time, from 1 hour to 7 days. We have controlled-rate orifices calibrated for 1, 3, 8, and 24 hours. Additionally, we can supply a digital electronic LCD timing valve with up to 20 start/stop events which can be programmed over a one week period with a one minute sampling resolution.
- Very sensitive. Reporting limit is 0.5ppbv for most compounds.
- Widest concentration range. We can inject up to 500 mL of air sample, or we can perform static dilution techniques for samples with high concentrations of pollutants. This eliminates the possibility of "Out of Range" samples.
- Best accuracy and precision. Reproducibility and accuracy is outstanding and far better than popular (and cheaper) techniques.
- Regulatory approval. Widely regarded as the correct way to sample and analyze volatile organic compounds in air.
- Stable. The holding time for samples in the SUMMA canister at ambient
temperature is 30 days for T014 (14 days for TO15), not
24-48
hours as with Tedlar Bags.
- Cost will be lower if multiple samples are submitted, or if an abbreviated analyte list is required. The canister remains the property of KAR Laboratories - it must be returned. Your results will be reported to you in 10 working days or less. The cost of this test is higher because of the specialized equipment and calibration standards consumed, multiple analysis requirements, and prescreening/verification using an alternate technique (we use EPA Method 0040 & 8260 for pre-screening).
If you want it done right, TO-14/TO-15 is the method to use.