Formatted Title
Shovel or Scalpel? Modern Simulated Distillation, Updated TPH Fraction Methods to Define Contamination and Remediate
Background/Objectives
Analytical techniques for total petroleum hydrocarbon (TPH) analysis of pure product, soil, sediment and water samples have not been updated for more than a decade. Conceptual site models and risk management decisions at petroleum release sites require a higher level of understanding of the hydrocarbon composition. However, traditional TPH analytical techniques provide no speciated data regarding the hydrocarbon composition. RSLs for EPH categories apply chemical compounds that are either not representative or poorly describe the actual risk and provide minimal data for remediation effectiveness.
Approach/Activities
Advanced simulated distillation and 2-D laboratory analysis (GCxGC) allows for improved conceptual site models and risk assessment to be performed via an updated method for amplified site characterization. When we apply a second separation on a column with a different stationary phase, so we can pull apart complex samples, based on two different chemical properties (for example, volatility and polarity) and it means you get cleaner spectra, for more confident identification and allowing more information on sample composition to be uncovered.
Results/Lessons Learned
Considering that TPH analyses and standards are inconsistent, determination of health risks and development of toxicity values for mixtures of hydrocarbons are problematic. Most risk assessors prefer to assess individual constituents rather than evaluate TPH concentrations. Providing a more applicable, fractionated TPH concentration has been used via Massachusetts Department of Environmental Protection. The next evolution in analytical technique is available providing the ability to compare results across different samples and with the parent product if available. Simulated distillation and TPH speciation through forensic fingerprinting, with target compound selectivity, two-dimensional resolution, and peak differentiation provides an accurate tool to better define the nature and associated risk of hydrocarbon mixtures at petroleum release sites.
The improved simulated distillation/TPH methods would avoid unnecessary remediation or even more important underestimation of potential risks attributed to petroleum hydrocarbons in various media. Site study results from October and November 2023 will be presented. It is time to stop using a catch all total value “shovel” method and implement precision science-based technology to ensure people and the environment are protected.