Improved method for the determination of polycyclic aromatic hydrocarbons in contaminated groundwater and soil samples at trace levels employing GC-MSD technique

The objective of this study was to develop and optimise an analytical method with improved detection limits for the routine analysis of trace level polycyclic aromatic hydrocarbons (PAHs) in contaminated groundwater and soil samples. The method presented here eliminates the large volume extraction and manual pre-concentration minimising the loss of analytes as well as reducing the risk of handling toxic solvents. For this purpose, the method was performed on a GC-MSD system integrated with Large Volume Injection (LVI) port controlled through Programmed Temperature Vaporisation (PTV) mode. While LVI can handle large volume injections, PTV has the unique capability to vent the solvent and pre-concentrate the sample in the liner prior to column separation resulting in improved detection limits. Evaluation of the method showed the calibration curves acquired in selected ion monitoring (SIM) mode have excellent R2 values of 0.999 or greater for the low concentration range of 4-72 ppb. Recovery percentages of the soil samples were 95%-121% and 98%-118% for the laboratory control spike and matrix spike, respectively. The groundwater samples have recovery values of 81%-91% and 84%-96% for the laboratory control spike and matrix spike, respectively. A quantification/reporting value of 4 ppb was selected as the in-house limit, which is within +∕−0.7 ppb at the 95% confidence level. The method has been shown to be reliable for routine environmental monitoring of PAHs at trace levels from the contaminated sites.