Detection of Petroleum Contaminants in Soil Based on Multiphoton Electron Extraction Spectroscopy

The fast detection of petroleum contaminants in soil is very important and urgent for environmental monitoring. Generally, the current methods for the detection of these kinds of contaminants require complex sample pre-treatment with the excessive use of toxic and volatile organic solvents or the analytical performances are not satisfactory enough for field-based applications. A method based on photocurrent measurements, named multiphoton electron extraction spectroscopy (MEES), was proposed to detect petroleum contaminants in a soil matrix in this study. The results showed that the resonance-excited wavelength of 326 nm had the highest selectivity for petroleum determination after a wide range of wavelengths was scanned with an optical parametric oscillator (OPO) laser under ambient conditions. Linear regression was performed to fit the intensities and areas of the photocurrent curves to the petroleum concentration via a least squares method. A LoD of 0.0091 wt% was achieved with an R-2 value of 0.9912 and a RMSECV value of 0.013 wt% via the peak area approach, whose sensitivity and accuracy were slightly higher compared to the peak intensity method (LoD of 0.011 wt%, an R-2 value of 0.9315 and a RMSECV value of 0.020 wt%). This research provided us with a new method for the rapid determination of petroleum contaminants in soil samples with high accuracy.