Even if you use CPT technology daily to test soil, you may not be aware of the further advantages CPT testing has to offer beyond its more commonly used or basic geotechnical functions. Take fluorescence detection, for example. Fluorescence detection records a fluorescent response to a specific excitation of automatic carbons in a chemical. This excitation is caused by an ultraviolet light source. But you’re probably wondering how fluorescence detection can help you. Read on to find out!
The Common Uses of Fluorescence Detection
Before delving into scenarios in which fluorescence detection is useful, let’s take a closer look at how it works in relation to CPT. One method of fluorescence detection is done using handheld UV lights to investigate above ground contamination. With CPT, the UV light source is placed in the cone, with fiber-optic cables transmitting resulting fluorescence to the surface where it can be measured in voltage responses. At Vertek CPT, we use LEDs and mercury lamps to generate UV light.
Whether above ground or below, fluorescence detection reveals two ranges of fluorescent emissions: 280-450 nm wavelengths and wavelengths above 475 nm. The test is capable of detecting a variety of chemicals within these ranges, including:
- Polycyclic aromatic hydrocarbons (PAHs)
- Coal tars (DNAPL compounds) if mixed with compounds, like fuels
- Creosote sites that contain naphtalene, anthracene, BTEX and pyrene
- Total petroleum hydrocarbon values (TPH) as low as 100 ppm in sandy soil
Fluorescence detection is also able to detect a number of contaminants, such as jet fuel, diesel, unleaded gasoline, home heating oil and motor oil. As you can imagine, this makes fluorescence detection extremely beneficial at fuel spill sites and sites with leaking storage tanks.
However, if you already use CPT testing regularly, it’s worth considering fluorescence detection in other scenarios to add capability and additional opportunities, as it’s an easy and accurate way to increase safety for workers by preventing exposure to potentially harmful chemicals. In addition, you never know when you may encounter a site with contaminated soil; with fluorescence detection, you’ll be able to factor this in early on, preventing possible headaches or worse down the road.