Detection and identification of VOCs is required in numerous settings, including the petroleum industry, to ensure worker safety and compliance with environmental regulations.

Volatile organic compounds (VOCs) are a class of chemicals that includes a wide range of carbon-based molecules that readily evaporate and enter the atmosphere. VOCs are typically highly chemically reactive and often flammable, and many have serious health risks associated with exposure and the potential for environmental contamination. A need exists to monitor and identify VOCs present in a variety of contexts, including industrial and commercial settings for workplace safety and environmental monitoring of contaminated soil and water. A number of detection and analysis technologies for VOCs are in use today, chief among them is the photoionization detector, or PID.

PIDs make use of the fact that volatile organic compounds have low ionization potentials (IPs) compared with other gases, typically in the range of 7 to 12 eV. These devices operate by providing a source of light with a wavelength in the ultraviolet (UV) range. The gas is situated between two electrodes, across which an electric potential is applied. Ions are drawn to the negative electrode (cathode) and electrons are drawn to the positive electrode (anode) resulting in an electric current. This current can be measured and provides information about the presence of ionizable gases. Many PIDs are portable and hand-held, enabling rapid, on-site VOC detection.

While photoionization detectors can readily detect the presence of VOCs in concentrations down to ppb or even high ppt levels (depending on the VOC type), they do not provide specific information as to which VOC or VOCs are present in the air sample. On-site, selective identification can be done using colorimetric tubes or badges, but this technique is slow (requiring minutes to respond), inaccurate (often rated at 25% accuracy), and impossible to incorporate into an electronic monitoring system. Gas sampling followed with laboratory gas chromatography (GC) can be done, but requires a great deal of time and can be a costly on-going expense . Portable GC units are available, but remain costly.

SPID technology under development at Lenterra combines the concepts of traditional PIDs with the electron spectroscopy of the PIES technique. In much the same way as Penning ionization by helium metastable atoms, photoionization using monochromatic light involves a specific initial energy that is expended to liberate an electron (photoelectron), in this case the energy of the UV photon. Measurement of the electron energy spectrum allows for a selective determination of the VOCs present in the gas sample.

SPID technology is positioned to provide fast, in situ, cost-effective, portable detection and identification of VOCs, bridging the gap between non-specific portable methods and stationary benchtop analyzers.