PAH Analysis (Alkylated PAHs, HPAHs & PAHs in Air)
Alpha Analytical has considerable experience with the analysis of hydrocarbons in general and PAHs in particular. We have supported some of the largest, most demanding and highest profile hydrocarbon investigations in the world. Alpha offers a unique combination of the highest quality analytical capabiliities, as well as the capacity to process the large numbers of samples these types of projects typically generate both efficiently and in accordance with challenging timeframes. Alpha's PAH analyses range from the typical parent PAH compounds listed in the EPA Priority Pollutant list to PAH target compounds lists that also include their respective alkyl-substituted homologs.
Alkylated PAH Analysis
Alkylated PAH analysis can be used to support risk assessment applications. The USEPA has developed a tiered ecological risk assessment approach for contaminated sediments. In Tier 1, the potential bioavailability of PAHs is assessed based on the analysis of whole sediments, with the PAH concentrations detected evaluated against established equilibrium partitioning guidelines. In Tier 2, the potential PAH bioavailability is assessed by the analysis of the sediment pore water. Alpha supports both assessments, with the pore water analysis conducted using solid phase micro-extraction (SPME) analysis (ASTM D7363) for all of the Ecological Monitoring & Assessment Program (EMAP) 34 listed PAH compounds.
Heavy Molecular Weight PAH (HPAH) Analysis
In 2010, the USEPA released a draft document entitled "Development of a Relative Potency Factor (RPF) Approach for Polycyclic Aromatic Hydrocarbon Mixtures", EPA/635/R-08/012A. The RPF approach under review describes a procedures for assessing cancer risk from exposure to PAH mixtures. This document lists several, somewhat obscure, high molecular weight PAH compounds that are not commonly analyzed for and that have an associated high degree of analytical difficulty associated with them. Alpha Analytical offers this analysis, which would support risk assessment applications, for a majority of the additional PAH compounds listed in this document.
PAH Analysis in Air
Air monitoring for PAHs during MGP site remediation or to monitor for a possible vapor instrusion pathway has become increasingly more common. For MGP sites where vapor intrusion is a concern, Alpha has developed a target compound list that has the standard EPA Method TO-15 analytes plus a number of the 'MGP Indicator' compounds:
- Thiophenes: thiophene, methylthiophene, ethyl thiophene, benzothiophene
- Alkyl-substituted benzenes: 1,2,3-trimethylbenzene, 1,2,4,5-tetramethylbenzene
- Aromatics: indane, indene, naphthalene, 1-methylnaphthalene, 2-methylnaphthalene
This list is recommended in the NYDEC vapor intrusion guidance for MGP sites and is applicable to sites in other jurisdictions.
Alpha also offers EPA Method TO-13A analysis for PAHs in air monitoring programs and has extensive experience providing this analysis for conducting fence-line monitoring during remediation of MGP sites. As a cost-saving measure, the TO-15 method can be employed to conduct analysis of naphthalene if that is the only compound of concern on the TO-13 analysis. A number of comparison studies have been conducted and the results for naphthalene via the TO-15 and TO-13 methods are comparable. Alpha presented the following paper outlining our work conducted in support of one of these comparison studies at an Air & Waste Management Conference: "Comparison of Naphthalene Measurements between Laboratory Methods and an Ultra-fast Field Gas Chromatograph", Andrew P. Rezendes, Alpha Analytical, Eight Wallkup Drive, Westborough, MA 01581; Michael A. Marando, Raymond Siegener, Patrick P. King, Roy Desroschers, GEI Consultants, 400 Unicorn Park, Woburn, MA 01801.