Public Lab Research note

Nungesser test #2, UV and green lazer

by eustatic | September 09, 2013 16:32 | 43 views | 3 comments | #9306 | 43 views | 3 comments | #9306 09 Sep 16:32

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What I want to do

From the previous note, test the coal or petroleum coke sample for contaminants.

In addition to this testing, the Clean Gulf Commerce Coalition is working with Global Community Monitor to analyse drum samples of particles of coal that Plaquemines residents are breathing.

Here's the sample from last time. I left the drippings from the fork on top of the jar to show the results of what the mixture of coal chunk in mineral oil looks like.

Overnight, the sediment in the jar had settled. So the jar was briefly shaken to get the black liquid into suspension, then poured into the sampling vial.

My attempt and results

The green lazer test showed no discoloration, only green color before being dissipated into the mix

The UV test also showed no fluoresence of the blackened solution, only a limited penetration

Questions and next steps

I would like to confirm my visuals with the spectrometer.

I might wait for the sediments to settle and try again, this time with the spectrometer.

I should break out my mineral oil control, and compare the spectra.


Hi Scott -- it looks like the samples are too dense for light to pass through... ideally the source light (laser or UV) goes all the way through the sample without reflecting off anything (or minimally). I think this may be happening because the coal is not a solution, and something similar happened at the Gowanus Canal.

Is there any way to dissolve the coal? Or maybe filter out the sediment with a coffee filter or something to try to collect and concentrate the soluable parts of the sample? We may find that very little dissolves.

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I was going to wait for it to settle. Would that be the same as filtering? It certainly saves me precious time.

I was thinking the same, that mineral oil may not be the best, particularly if we are concerned with the contaminants being spread via water.

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settling would work too, sure -- i think the important thing is the solubility

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