Public Lab Research note

Fluorescence from oil spill residue & diverse spectrometer use

by warren | July 18, 2012 12:45 18 Jul 12:45 | #2862 | #2862

My long-term goal of using the PLOTS video spectrometer to identify oil contamination is looking closer than ever recently due to recent tests with a green laser. The above photo shows actual oil residue, dissolved in mineral oil (on the left) fluorescing strongly when shot with a green laser! The right-hand bottle is of mineral oil alone. I haven't yet been able to get a strong reading of this on a spectrometer but will be trying as hard as I can to do so in coming days.

I also wanted to point out a few other uses for spectrometry which have caught my eye. It's always made sense with a long-term, risky project like the PLOTS spectrometer, that we'd have to find other, easier uses along the way. That way, the device and our methodology can be refined in actual use, and we can slowly step towards pollution detection.

Early on, I found a very exciting community of like interest in the Atlanta Reef Club, where Giuliano Moschini made (and dramatically improved) the design to measure the output of coral-growing LED lights. I loved this because a) it treated what I thought was an early prototype as a fully functioning tool, and b) it was being used to test another DIY project -- their modified LED lights. Read more here:

More recently, contributor JoshMC has been measuring lights and other things, but I was very interested to see his post on UV spectroscopy of boiled water, Free & Clear laundry detergent, and bleach. What was neat was that he managed to identify a blue dye in the supposedly "free and clear" detergent! ( The idea of being able to police companies who make such claims using a simple and cheap tool is super cool.

Finally, an early suggestion from a soil researcher named Lucas Patzek was to identify striperust, a wheat disease which is distinctly yellow. Maybe the recent mobile spectrometer as well as the in-progress spectral matching system will make that possible from a mobile phone.


Very nice- such clear fluorescence! What kind of concentration of oil residue is in the left sample?

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Several things are exciting here, Jeff. It's great that the Atlanta Reef Club is using our tool! I am heading down there in August for an EPA conference, so I'll shoot them an e-mail.

As for the green laser fluorescence, I'm reading a little bit on lasers, but get a tad confused. It's green, so it must be emitting in the green spectrum there, but is its energy confined to the visible green wavelengths?

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Yes, the green laser is only a very narrow green color, so any other colors you see are emitted by the liquid itself, as it fluoresces. The green laser excited electrons in the sample, which release light in particular colors as they return to their original state.

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Yes, that's right -- but any infrared in the 1064 nm region is probably not visible in our device, or if it is, it'll be way off in the infrared region so doesn't really interfere with the visible light region we're looking at. See

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