Fast Semi-Automated Extractable Petroleum Hydrocarbons Fractionation and Cleanup Using Pentane and Dichloromethane

New Organic Monitoring Techniques
Poster Presentation

Prepared by , T. Hall

Contact Information: ruudaddink@toxicreports.com; 617-393-1713


ABSTRACT

Soil contamination from gasoline, diesel fuel, heating oil, kerosene, jet fuel leaks or spills is a common occurrence and a global environmental concern. Petroleum products are composed of over 250 compounds, making the analysis of all of them difficult. Some states, such as Washington, have created separate methods for extractable petroleum hydrocarbons (EPH) and volatile petroleum hydrocarbons (VPH). We developed a semi-automated method for fast and reliable extraction of aliphatic and aromatic compounds from complex extracts.
The semi-automated system uses a rotary workstation with a vacuum pump to perform the entire sample fractionation and cleanup in two stages with a few simple steps. It uses one pre-packaged 6 g neutral silica column in accordance with the Washington State method. In the first stage the column is conditioned with 40 mL hexane. In the second stage 1 mL sample in pentane is spiked with surrogates and loaded onto the silica. The column is eluted with 15 mL pentane, collecting the aliphatic fraction. It is then eluted with 40 mL dichloromethane, collecting the aromatic fraction. The fractions are reduced to 1 mL under a nitrogen stream at 30 oC. Analysis is done with GC-FID. Total processing time is 20 min. Up to six samples can be run in parallel.

Linear aliphatics (C9-C36) were analyzed with recoveries between 65-90%. Seventeen aromatics (PAHs) were analyzed with recoveries between 75-95 %. RSDs were < 10%. The semi-automated EPH system with certified 6 g silica gel columns gives excellent and fast separation of aliphatic hydrocarbons from aromatic hydrocarbons (PAHs). The combination of the EPH system and silica columns demonstrates consistent and reproducible data with a reliable high throughput.