March 2023

Welcome to our March 2023 newsletter. This month we have news about:

  • The HWOL Acronym system and understanding hydrocarbons tests
  • Presentation: Is ‘TPH’ always TPH?  or, What has your lab actually measured.

The HWOL Acronym System – for understanding your “TPH”

The HWOL Acronym System is a classification system that explains what type of TPH test was actually undertaken by a laboratory. This knowledge is important when deciding whether the TPH results are suitable for your application, whether it be for example, i) waste classification, ii) assessing the mineral oil in WAC or iii) completing your human health risk assessments. Having the wrong test can create unfavourable outcomes which could lead to a poor decision / cost you or your client more money.  

The full list of acronyms and explanation can be accessed here (see Table 1).

A white paper that explains “TPH” testing using 1D and 2D gas chromatography, basic hydrocarbons and the HWOL Acronym System can be downloaded here

While the HWOL Acronyms are included in .hwol data files, we also ask that all our .hwol labs  (list of hwol labs  include the acronyms in their PDF reports, alongside each TPH determinand. This means that you or the downstream users of the report can easily see what type of TPH test was undertaken (as you look at the numbers) and whether it is fit for purpose.

If the HWOL Acronyms are not in your report, please go back to your lab and ask them to update your report.

Example 1 – Waste Acceptance Criteria: mineral oil

Below is an excerpt from a WAC report, for a non-hazardous soil, where the waste owner wants to send the soil to the Inert class of landfill.

EH_1D_Total: Extracted Hydrocarbons_1D Gas Chromatography_Total of aliphatic and aromatic fractions.

The landfill regulations (Decision 2003/33/EC) refer to EN 14039:2004 for the analysis of hydrocarbons. This standard requires a chemical clean-up step (CU) to remove any non-petroleum hydrocarbons, such as the humics and fatty acids found in soils. This clean-up step would typically result in lower concentrations (as indicated in the example below).

EH_CU_1D_AL: Extracted Hydrocarbons_Clean-Up_1D Gas Chromatography_Aliphatic fraction only.

To meet the standard defined in the legislation for estimating mineral oil, the correct HWOL Acronym for mineral oil in WAC should be EH_CU_1D_AL.

Example 2 – TPH-CWG for use in either Human Health Risk Assessments and/or Waste Classification:

Below is an excerpt from a lab report for a customer who purchased TPH-CWG from their lab. The concentration shown is the sum of all the aliphatic and aromatic fractions between ~C8 and C40.

EH _2D_Total: Extracted Hydrocarbons_2D Gas Chromatography_ Total of aliphatic and aromatic fractions.

This lab has used a relatively new technique called 2D Gas Chromatography or GC-GC to get the result. However, what they haven’t done (as shown by the acronym) is apply a clean-up step (chemical CU or mathematical #1) to remove the non-petroleum hydrocarbons present, such as the humics found in soils.

The original TPH Criteria Working Group analytical technique (TPHCWG 1998) requires a clean-up (CU) to remove non-petroleum hydrocarbons. Also note that it describes a separate analysis to measure the volatile components found between ~C5 and C10.

For the carbon bands between C10 to up to C44, TPH-CWG describes two chemical clean-up steps, the first to elute the aliphatic fraction, the 2nd to elute the aromatics fraction.  Depending on the amount of non-petroleum hydrocarbons present in the soil (or any other waste), this typically results in reduced concentrations, as exampled below.

EH _CU+HS_1D_Total: Extracted Hydrocarbons_Clean_Up +Plus HeadSpace_1D Gas Chromatography_Total of the aliphatic and aromatic fractions.
EH_2D_#1+HS_1D_Total: Extracted Hydrocarbons _2D Gas Chromatography_minus the humics +Plus HeadSpace analysis_1D Gas Chromatography_Total of aliphatic and aromatic fractions.

The table shows two possible GC methods that could be utilized by a lab; the conventional 1D Gas Chromatography technique and the newer 2D Gas Chromatography technique. As many labs have moved to 2D-GC (or GC-GC), you should check your results to see whether the lab has included either a chemical clean-up (CU) or a mathematical clean-up (#1) to ensure that you get results more equivalent to the original 1D-GC TPH-CWG standard (i.e. lower concentrations, that reflect only the hydrocarbons produced from the refining of crude oil).

Recent presentation to the East Land Quality Forum

On March 9th, Ian Bishop gave a presentation to the East Land Quality Forum titled : “Is ‘TPH’ always TPH?  or, What has your lab actually measured?”
Part 1 of the presentation looked at how the laboratories undertake various “TPH” tests and how the HWOL Aconym System plays a part in helping us understand which type of “TPH” test was actually undertaken; one critical question being whether a clean-up step (CU or #1) was undertaken. Part 2 of the presentation explains how 1D and 2D gas chromatography works while Part 3 explains what we call “TPH” forensics; how a variety of hydrocarbon tests can shed more light as to the type of hydrocarbons present in a waste; in particular, are the hydrocarbons from the refining of crude oil or from some other source, a source that might not make the waste hazardous.

To view the presentation you may download it from

TPHCWG, 1998. “Analysis of Petroleum Hydrocarbons in Environmental Media”, Total Petroleum Hydrocarbon Criteria Working Group Series, Volume 1, Amherst Scientific Publishers, Amherst, Massachusetts, March 1998.