This is a general background paper talking about the fundamentals of measuring TPH using mid infrared and near infrared. It discusses the spectral peaks to use, the potential interferences, the effects of variations in soil texture and soil type and monitoring the degradation of hydrocarbons over time. It also compare the results of different calibration methods namely linear regression versus multiple linear regression versus partial least square regression. Several IR instruments, including RemScan, were compared.
- Infrared spectroscopy can be used to for rapid detection of petroleum contamination in soil.
- Mid infrared part of spectrum is more sensitive to TPH than near infrared.
- Portable mid-infrared collected similar spectra as the laboratory benchtop mid infrared spectrometer. Therefore, the portable MIR spectrometer could be used as a reliable soil sensor.
- Clay and carbon contents were found to decrease the TRH spectral signal.