Spills and releases of petroleum fuels are the largest source of environmental contamination in the United States. Massachusetts published a method that addresses the need to account for semi-volatile Aliphatic and aromatic fractions of gasoline using gas chromatography (GC) analysis and a flame ionization detector (FID). This method was designed to measure the collective concentrations of extractable aliphatic and aromatic petroleum hydrocarbons in water and soil/sediment matrices. Extractable aliphatic hydrocarbons are collectively quantitated within two ranges, C₉ – C₁₈ and C₁₉ – C₃₆. Extractable aromatic hydrocarbons are collectively quantitated within the C₁₁ – C₂₂ range.

Aromatic and aliphatic compounds are separated from each other by processing the sample through silica gel cartridges. The extracts are then analyzed using two separate calibrations. The reason for this stems from data suggesting that aromatic compounds are more toxic than aliphatic compounds. This approach, known as Extractable Petroleum Hydrocarbons (EPH) Method, characterizes sites according to their toxicity. Because this method is unique in its ability to determine human health hazards, and yet can still be used to calculate diesel range organics; it has been adopted by other states in the US and in Canadian provinces.

Resprep EPH Fractionation Spe Cartridges (cat # 25859) provide method-specific performance for EPH analysis of soil and water samples through complete separation of aliphatic and aromatic compounds into distinct fractions, while providing extractable background levels guaranteed to fall under the strict reporting limits of Massachusetts and New Jersey EPH methods. Restek’s newly optimized silica gel cartridges have superior lot-to-lot reproducibility and storage stability ensured by rigorous QC testing and moisture-resistant packaging. Resprep EPH Fractionation SPE Cartridges from Restek are manufactured in a strictly controlled environment with the simple goal of giving you consistent results – every day, every time. Resprep cartridges provide easy, reproducible, and guaranteed EPH analysis.

The fractionation process is very critical to accurately determine the amount of aliphatic versus aromatic compounds. As shown in Figure 1, the fractionation of aliphatic compounds includes C₉ – C₃₆ and the surrogate 1-Chlorooctadecane (COD). COD is a good marker for the end of the aliphatic range. The beginning of the aromatic range starts a couple milliliters later with the first compound, 2-Methylnaphthalene, starting to elute.

The importance of a reproducible and background free silica gel cartridge will be shown in the next segments of this EPH blog series.