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petroleum analysis

Hydrocarbon Forensics

Analytical Capabilities in Support of Hydrocarbon Forensic Investigation Applications

Alpha Analytical has considerable experience supporting the largest, most demanding and high-profile forensic hydrocarbon investigations in the world. Alpha offers a unique combination of the highest quality analytical capabilities as well as the capacity to process a large number of samples efficiently, and in accordance with the challenging time frames typically required by these types of projects. A world class environmental analytical laboratory, Alpha Analytical provides definitive, legally defensible analytical data. Our basic GC-FID Petroleum Hydrocarbon Identification (PHI) analysis provides some qualitative information which would suggest a possible fuel type. For clients that  require forensic data interpretation, Alpha can easily recommend a qualified third-party to perform that service. We believe this approach -- generating analytical data independent of the qualitative assessment-- provides the most objective information.

Alpha offers the following analyses for forensic hydrocarbon investigation and risk assessment applications for all sample media (i.e. air, aqueous, soil, sediment, tissue, and non-aqueous phase liquids (NAPL)):  

Petroleum hydrocarbon identification, saturated hydrocarbons, alkylated polynuclear aromatic hydrocarbons, geochemical biomarkers, PIANO and air-phase PIANO analysis.

PHI with Qualitative Narrative

Alpha refers to our most basic GC-FID hydrocarbon analysis as Petroleum Hydrocarbon Identification (PHI). This method is analogous to a “qualitative TPH” analysis that a commercial environmental laboratory would provide, with some important differences. PHI is based on a modified Method. Alpha utilizes an 80-minute analytical runtime to maximize chromatographic resolution. During this process, Alpha employs the most appropriate sample extraction procedure depending on whether the sample is aqueous, soil, sediment, tissue, or free product. 

Alpha has a dedicated and experienced hydrocarbon analytical staff that performa all of our forensic hydrocarbon analyses, including PHI. A cursory qualitative narrative is included with this analysis which outlines the hydrocarbon range the product elutes in, as well as a discussion of what the sample unknown is most similar to.This tentative identification is based on an interpretation of the chromatographic data utilizing pattern recognition and boiling point ranges, and the best match between the sample unknown and our extensive product reference library. The relative elution range of the sample material, based on a comparison with a n-alkane reference standard, is also provided along with chromatograms of the sample and the closest reference product.

Saturated Hydrocarbon Analysis (SHC)

Like Petroleum Hydrocarbon Identification, SHC analysis is also based on a modified Method 8015 approach for extractable hydrocarbons. SHC analysis is also applicable to aqueous, soil, sediment, tissue or free product samples. This method also utilizes the same 80-minute chromatographic runtime as PHI that encompasses n-alkane hydrocarbons and selected isoprenoids in the C9 through C40 range.  Data for 32 individual n-alkanes and five isoprenoids is reported, as well as the total concentrations of saturated and total petroleum hydrocarbons.  There is no qualitative narrative associated with this analysis.

It should be noted that the difference between SHC and PHI analyses is the data that is reported. If requested, we can provide both SCH and PHI data generated from the single GC-FID analysis. This combination would include the PHI qualitative narrative as well as the SHC target compound specific information.

 Whole Oil by GC/MS or GC/FID

The whole oil analysis is a performance-based method for analyzing NAPL (non-aqueous phase liquid) samples that may be derived from various sources. This method is appropriate for a range of non-aqueous products, such as oils, gasoline, heavy fuels, and distillates. This analysis will provide a high resolution GC-FID 120 minute chromatogram that can provide the basis for determining its overall composition (C4-C44).The sample chromatogram and alkane reference standard chromatogram is provided. There is no additional qualitative or quantitative information provided with this analysis

Alkylated Polynuclear Aromatic Hydrocarbons (PAH) Analysis

Alpha offers an extended list of polynuclear aromatic hydrocarbons (PAH) beyond the routine EPA Priority Pollutant List parent PAH compounds using a modified Method 8270 SIM approach.  Alkylated homologs of the parent PAHs can provide valuable information about the nature of the unknown product, including potential sources, and the allocation of responsibility for a given release. The relative abundance of the alkylated homologs, in relation to the parent PAH compounds, can help differentiate PAHs derived from petroleum (petrogenic) and PAHs resulting from combustion, or partially combusted, pyrogenic organic matter. Alkylated PAH analysis can also be used to support risk assessment applications. The  EPA has developed a two-tiered ecological risk assessment approach for contaminated sediments that Alpha supports. In Tier 1, the potential bioavailability of PAHs is assessed based on the analysis of whole sediments, with the detected PAH concentrations  evaluated against established equilibrium partitioning guidelines. In Tier 2, the potential PAH bioavailability is gauged by the analysis of the sediment pore water. Pore water analysis can be conducted on pore water samples collected in the field, generated in the laboratory by centrifuging sediment, or by using solid phase micro extraction (SPME) analysis (ASTM D7363-13). There is no qualitative narrative associated with this analysis.

Geochemical Biomarker Analysis

Geochemical biomarker analysis can be performed as an extension to alkylated PAH analysis or as a standalone method. Like PHI and SHC, this procedure is also based on a modified Method 8270 SIM approach. The polycyclic alkane compounds of biological precursors are used extensively in petroleum geochemistry to differentiate sources of petroleum oil. Because of their refractory nature and resistance to biodegradation, the presence of these compounds helps to identify oils after a released petroleum residue has been weathered to the point that most of the saturated hydrocarbon and PAH diagnostic character is lost.  There is no qualitative narrative associated with this analysis. 

Paraffin, Isoparaffin, Aromatic, Naphthenes and Olefin (PIANO) Analysis

Based on a modified Method 8260 approach, Alpha Analytical provides an innovative analytical tool for characterizing light-end refined products such as gasoline or jet fuel. This procedure allows for the identification and measurement of more than 120 volatile Paraffin, Isoparaffin, Aromatic, Naphthenes and Olefin (PIANO) compounds with boiling points up to 250 °C. 

This analysis can also be performed on soil gas and air samples utilizing a modified TO-15 analytical approach that uses fused silica-lined summa canisters for sample collection. This air-phase PIANO analysis, can provide an additional line of evidence for vapor intrusion-type applications, as well as other applications.  There is no qualitative narrative associated with this analysis.

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