Update to Massachusetts Air Petroleum Hydrocarbons (APH) Method
The Massachusetts Department of Environmental Protection (MassDEP) recently updated and finalized their Air-Phase Petroleum Hydrocarbons (APH) analytical method. The APH method, which had been in draft format since February 2000, was completed last year by a MassDEP Workgroup and approved after a month long public comment period in December 2008. The committee was comprised of MassDEP personnel, laboratory experts and data users.
The most significant updates to the APH method include:
- Analyte List Revisions – 2-Methylnaphthalene was removed from the target analyte list and is no longer considered an air-phase petroleum hydrocarbon. In addition, laboratories will no longer report the “unadjusted” hydrocarbon ranges.
- Calibration Standards Revisions – Indene, hexylcyclohexane and 1-methynaphthalene were removed as hydrocarbon range calibration standards/retention time markers, due to poor performance and stability in the whole air matrix.
- Standard Preparation – The newly revised method will only allow vapor phase standards to be used for calibration. (Previously, in the draft method, methanol based standards were allowed.)
- Calibration & Quality Control Requirements, Holding Time and Performance Standards – Many small changes were made in order to make the APH method consistent with EPA Method TO-15.
The MassDEP APH method is currently the only existing method to look at vapor phase hydrocarbons in a risk based corrective action approach (i.e. with fractionated aliphatic and aromatic ranges). Going beyond EPA Method TO-15 or a traditional total petroleum hydrocarbons (TPH) approach, this method provides more specific information about the type of hydrocarbon contamination at a site.
As an example of the utility of the APH method, Figure 1 shows the total ion chromatogram for a soil gas sample collected at a site impacted by historical subsurface petroleum product contamination. For this example, all the APH target compounds (1,3-butadiene, benzene, toluene, ethylbenzene, xylenes, MTBE, and naphthalene) as well as several other petroleum indicator species (1,2,4-trimethylbenzene, 1,3,5-trimethylbenzene, n-nonane, n-decane, n-dodecane, n-undecane) were not present above the laboratory reporting limit. However, as is visually evident, there was still a strong weathered petroleum pattern present in the sample. The hydrocarbon ranges reported in the APH method were able to capture this information which otherwise might have been overlooked in a basic review of the numerical results.
Figure 1. – Total Ion Chromatogram of Real-World APH Sample
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References (Current as of December 2008)
1. MassDEP Method for the Determination of Air-Phase Petroleum Hydrocarbons (APH), December 2008. Available at: http://www.mass.gov/dep/cleanup/laws/qaqcdocs.htm#IV
2. MassDEP Standard Operating Procedure for Indoor Air Contamination, SOP-BWSC-07-01, August 2007 (made available April 2008). Available at: http://www.mass.gov/dep/cleanup/laws/policies.htm#iasop
3. MassDEP Indoor Air Sampling & Evaluation Guide, WSC Policy #02-430, April 2002. Available at: http://www.mass.gov/dep/cleanup/laws/policies.htm#indair
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Tags: 4-trimethylbenzene, 5-trimethylbenzene, Air Petroleum Hydrocarbons, Air-Phase, APH, APH method, APH target compounds, Chromatogram, EPA Method TO-15, ethylbenzene, hydrocarbon, hydrocarbon contamination, Massachusetts, MassDEP, Methods, n-decane, n-dodecane, n-nonane, n-undecane, petroleum hydrocarbon, petroleum product contamination, Standard Preparation, subsurface, toluene, Total Ion Chromatogram