Comparative evaluation of TPHs standards in the analysis of petroleum-contaminated, and remediated soil

Commercially available Total Petroleum Hydrocarbons (TPHs) standards have been widely used for instrumental analysis of TPHs in soils and other environmental matrices. However, there are concerns about the universality of these standards developed in one region of the world to reliably estimate TPHs in environmental matrices in other regions, which prompted this investigation. TPHs standards were prepared from contaminating crude oils at polluted sites at Tibshelf, UK, and Ogoniland, Niger Delta, Nigeria. The prepared standards were used in comparison with some commercially available TPHs standards (TPHs-gasoline diesel range and TPHs C10-C40) for assessment of TPHs levels in the contaminated soil samples treated for phyto and myco-remediation. Results obtained revealed significant differences in the quantification of TPHs between these standards. The TPHs standards prepared from the contaminating crude oils estimated higher levels of TPHs in the soil samples compared to those of the commercially available standards. In assessing the % of TPHs reduction in the remediation experiment, all the standards provided similar estimations of TPHs reduction, with no significant differences. The result revealed that although all the TPHs standards provided consistent evaluation of TPHs remediation in all cases, the commercially available TPHs standards may underestimate the concentration of TPHs in certain environments during pollution incidents. Therefore, with respect to toxicological evaluations, there is a need for TPHs standards specifically developed for a region of interest to be used. This study offers a good insight on how such standards can be prepared.