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Pagel of 3 Vicki McCartney [EH] From: Jennifer Miller[jmiller@airtoxics.com] Sent: Friday, June 26, 2009 9:51 AM To: Vicki McCartney [EH] Cc: Karen Lopez; Kelly Buettner; Kyle Vagadori; Jennifer Miller Subject: RE: Concerns about air data Vicki, I responded to you with a very short answer, making some assumptions that may or may not apply. Please forward this onto any of your fellow regulators: Collecting air samples in Tedlar bags is a modification of the TO-15 method. Storage in Tedlar bags mayor may not be appropriate depending on the data objectives of the project. Tedlar bags can contribute to artifacts in the sample and losses due to adsorption and diffusion through the Tedlar material. The extent of these affects on data quality is a function of sample storage time, the specific target compound, and the reporting limits required. Tedlar bags are most successfully applied to high concentration samples for target VOCs that have sufficiently high vapor pressure. (For example, s low vapor pressure compound such as Naphthalene, shows immediate losses when stored in a Tedlar bag.) Technically, TO-3 was written as an on-line measurement technique and does not describe any storage container. However, most practitioners utilize similar storage containers as TO- 15. The same limitations apply when using Tedlar bags for TO-3. With regard to reporting CC by 8260B and 8015M, it is unclear from the information provided how the calibration standards are being introduced into the instrument. Neither 8260B nor 8015 describe appropriate protocols for injecting vapor samples which leaves it up to the laboratory to design (and hopefully validate)an introduction technique to insure that vapor concentrations are accurately measured. Oftentimes, labs will use methanol standard mixes and inject into the sparge vessel of the purge and trap such that the calibration curve is based on liquid standards. Unfortunately, this approach does not validate the accuracy and precision of the vapor concentrations. For example, we have seen good performance for naphthalene when calibrating 8260B using methanol mixes, but when introducing a known concentration of naphthalene vapor standard, recovery was <50% against the 'liquid' curve. At a minimum, the lab should analyze a known concentration of vapor standard to verify that their liquid curve is generating accurate vapor concentrations. In contrast, Method TO-15 requires vapor phase calibration standards to generate the initial calibration and daily calibration check. The vapor standards are introduced into the unit in the same manner as the vapor phase samples. Best Regards, Jennifer Miller Technical Sales Air Toxics Ltd. 180 Blue Ravine Road, Ste. B Folsom, CA 95630 916/605-3408 Lmi'ller@airtoxics.com www.airtoxics.com 800-985-5955 6/26/2009