Most laboratories have a range of routine suites targeting organic compound groups. The compounds reported in suites are typically based on key contaminants of concern or industry guidelines, however suites do not always cover every organic contaminant that may be found in your sample.
As a result, practitioners often use a comparison of target compound analyses (via suites) against TRH (as a screen) to assess the potential presence of high levels of ‘unknown’ organics
When using TRH (C6-C10 or >C10-C40) as a screen, concentrations that are not accounted for by target VOC or SVOC analytes may indicate the presence of non-target organics. If the levels of ‘unknown’ TRH are high, this may warrant further investigation to identify and determine whether these non-target organics are benign or otherwise. Knowing what these compounds are can be beneficial for effective risk assessment and show a level of due diligence to assist auditor sign off. Awareness of the potential presence of non-target organics is of particular value for complex industrial sites (where varied and unique organic contaminants may exist and at significant concentrations) and for sites where historical information is limited especially with imported fill.
One of the key tools to assist with these investigations is the use of VOC and SVOC Scan for Unknowns, reporting both qualitative identification and semi-quantitative concentrations of non-target VOCs and SVOCs in both soil and water via Gas Chromatography Mass Spectroscopy (GCMS). Analysis follows procedures stipulated in USEPA Methods 8260 and 8270 for Tentative Identification and Quantification of Non-Target Analytes.
What is inside this article?
- GC/MS Qualitative Identification
- Example - VOC Analysis
- Quantification and Reporting
- Targeted Unknowns
- Example Report
- Sampling Requirements and Holding Times