Spectrometry Sampling
activity:spectrometry-sampling

**How do you test liquid or solid samples with your [DIY Spectrometer](/wiki/spectrometer)?** Read about ways to prepare and scan samples here, and [read about different tests you can do with your spectrometer](/wiki/spectrometry-activities). ## Questions [questions:spectrometry-sampling] **** ## Sample containers What do you store liquid samples in? A good sample container has flat sides, so you can shine lights (and lasers) through it without lots of reflections. There are lots of different [affordable test tubes on Amazon](https://www.amazon.com/s/?field-keywords=test%20tubes), but they're mostly round. Flat-sided test tubes are often called **cuvettes** and are specifically for spectrometry. It's also good to have the light travel through a consistent amount of the sample -- many cuvettes (traditional spectrometry sample containers) are 1cm x 1cm, so the light always goes through 1cm of the sample. [![dropper.jpg](https://i.publiclab.org/system/images/photos/000/001/730/medium/dropper.jpg)](https://i.publiclab.org/system/images/photos/000/001/730/original/dropper.jpg) [![Cuvette_with_penny.jpg](https://i.publiclab.org/system/images/photos/000/001/731/medium/Cuvette_with_penny.jpg)](https://i.publiclab.org/system/images/photos/000/001/731/original/Cuvette_with_penny.jpg) _A square-sided bottle, left, and a cuvette, right (photo from [Wikipedia](http://simple.wikipedia.org/wiki/Cuvette))._ Unfortunately, we've found that cuvettes with plastic stoppers will leak when filled with oil and not kept upright (for example if you travel with them). A really nice source of completely sealable rectangular 1/4 oz glass jars which are pretty perfect for sampling can be found for $3.50 for a ten-pack here (see image below of 2 on top of a flashlight): http://www.sciplus.com/p/WHITCAP-BOTTLE_48212 **Other sample container options** * $20 (w/ shipping) 100x plastic (polystyrene) cuvettes: http://www.amazon.com/Cuvette-Polystyrene-Macro-2-5Ml-4-5Ml/dp/B008H5XJ9E/ (no caps) * $9 100x cuvette caps: http://www.amazon.com/Azzota-A920-Cuvettes-Caps-100/dp/B005YOJPLC/ * $22 Quartz cuvette (transparent in farther UV range): http://www.amazon.com/Quartz-Cuvette-standard-10mm-spectrometer/dp/B00DWXFIS6/ **** ## Water sampling Water is usually very clear in small amounts -- even murky water in a small container will look pretty transparent. That makes it hard to measure with spectrometry unless you shine light through a *lot* of it. But some tests have been done -- see this example of a scan of water from the Charles River before and after 7 days of settling, by [Jeff Hecht](https://spectralworkbench.org/sets/show/330): [![charles-river.png](https://i.publiclab.org/system/images/photos/000/001/732/large/charles-river.png)](https://spectralworkbench.org/sets/show/330) **** ## Oil sampling However, most research in Public Lab to date has focused on oil spectroscopy -- attempting to identify petroleum residue in sediments. [![IMG_20140722_230007_2.jpg](https://i.publiclab.org/system/images/photos/000/005/452/large/IMG_20140722_230007_2.jpg)](https://i.publiclab.org/system/images/photos/000/005/452/original/IMG_20140722_230007_2.jpg) To identify oil contamination, we [have been attempting](/tag/fluorescence) to illuminate oil samples with UV flashlights and green lasers, which can make some oils fluoresce, or glow, as pictured above. The basics of sample preparation for oil identification are still being refined, but our best practices to date can be found on the [Oil Testing Kit page](/wiki/oil-testing-kit) **** [![Flame spectroscopy](https://i.publiclab.org/system/images/photos/000/001/634/medium/IMG_1794.JPG)](https://i.publiclab.org/system/images/photos/000/001/634/original/IMG_1794.JPG) _Burning potato chips to measure the sodium emission spectrum from the NaCl (salt)._ ## Flame spectroscopy Another type of spectrometry which involves measuring the light of a flame and can detect specific elements (not molecules) as they emit light at very specific "peaks" -- narrow wavelength bands. Besides flames, these "emission lines" can be produced by exposing gases or sometimes liquids to UV light, lasers, or electric fields (as in a fluorescent bulb). The fluorescent bulb spectrum [you get when calibrating](/wiki/spectral-workbench-calibration) is an example of a mercury emission spectrum. Emission lines are produced by atoms, not whole molecules (the latter produce absorption lines, which we might still be able to detect since we have the flame -- a good broad-spectrum light source -- but that is just a theory at this point). So sulfur and carbon are possible targets, but we won't be able to distinguish CO2 from CO. **Basic setup:** For a more complete description, please read about the "flare spectroscopy activity" below, however, the basic setup involves simply pointing a spectrometer at a flame (which can be difficult to line up if the flame is far away), and later comparing any peaks to known peak locations of looked-for elements. We are compiling a collection of such known elements by importing "idealized" spectra from the NIST database, a process which you can [read more about here](/notes/warren/08-13-2013/importing-spectra-from-nist-and-webmineral-com-to-spectral-workbench). Read more about flame spectroscopy: - [Flare spectroscopy activity](/wiki/flare-spectroscopy-activity) (with description of experimental setup) - Flare spectroscopy research: [http://publiclab.org/tag/flare](http://publiclab.org/tag/flare) - A report from user [straylight](/profile/straylight) on a classroom activity involving [measuring different elements in a bunsen burner flame](/notes/straylight/10-14-2012/classroom-flame-spectroscopy) - A listing of imported emission spectra of elements from the NIST database so far: [https://spectralworkbench.org/tag/nist](https://spectralworkbench.org/tag/nist) --------- ### Activities [activities:spectrometry-sampling]...


Author Comment Last activity Moderation
warren "It's odd -- I see the graphs. Straylight, can you contact web@publiclab.org so we can figure out what's going on there? " | Read more » about 8 years ago
straylight "Thanks for the question. My apologies that all of the graphs appear to have vanished (they have for me). Not sure why, maybe a hosting issue. Anyw..." | Read more » about 8 years ago
anjohn12 "Quick question, I'm trying to do something similar for a school project. Shouldn't the absorbance of the sample be the negative log of the percent ..." | Read more » about 8 years ago
ethanbass "@warren - Please do send one along. I'd be happy to do some comparisons. " | Read more » about 8 years ago
warren "Oh, did @matej end up with those? " | Read more » about 8 years ago
liz "@warren - i do not have any of the polystyrene cuvettes " | Read more » about 8 years ago
dhaffnersr "I agree Jeff on the toxicity of using Hexane as a solvent, that's why I have been using Isopropyl 91%. I also have been using Ethanol (C2H5OH,) it'..." | Read more » about 8 years ago
taramei "@gretchen can we discuss make a general note about how plastics dissolve in solvents; this is an important concept for any kit user to understand f..." | Read more » about 8 years ago
warren "@liz & @matej - did the polystyrene cuvettes last, or did they get melty? I like the nalgene-centric mixing process we used; much easier mixing..." | Read more » about 8 years ago
warren "And do you have a link to the HAZCAT guide from Randy? Thanks! " | Read more » about 8 years ago
warren "Oh, just noticed -- on your dielectric fluid scan, you need to select a new cross section -- the top row of pixels is blank. Great post! " | Read more » about 8 years ago
warren "@ernestootero -- what about methanol, which is somewhat less toxic than hexane or acetone? Have you used isopropyl? " | Read more » about 8 years ago
dhaffnersr "Hey Warren, thanks for your comment on my lab set up. Yeah I'm trying to do oil contamination testing here were I live (city point hopewell va) the..." | Read more » about 8 years ago
tonyc "Very cool. If you're going to try to make a cuvette frame, another line of thought is the minimal version, which tucks into the DSK housing itself..." | Read more » about 8 years ago
eustatic "I owe Matej samples. Stevie gave me some brown jars, so i can divide the bulk samples and mail them to him. then, we can zap them independently! S " | Read more » about 8 years ago
warren "Just a note that I found this interesting article (not peer-reviewed; Photonics is an industry trade journal, I think) which discusses LED input li..." | Read more » about 8 years ago
warren "Tar Balls over time? Scott, I'd be really interested if you collected a set of a bunch of different tar ball spectra, esp. in different states of ..." | Read more » about 8 years ago
warren "We'd discussed using isopropyl alcohol at the Barnraising; I'd love to know if it can dissolve oil. Matt Pendergraft (@Matt_P) mentioned doing this..." | Read more » about 8 years ago
warren "Just looping in @ethanbass, @ygstcu, @matej, & @tonyc who were part of this discussion/design process, @stevie and @gretchen, and @stoft becaus..." | Read more » about 8 years ago
ernestootero "Another solvent may do the trick of de-sorbing the oil. It should be highly volatile. Hexane or Acetone? " | Read more » about 8 years ago
liz "Fantastic and entertaining write-up @eustatic -- thanks all! " | Read more » over 8 years ago
Matej "@pdhixenbaugh: There are different oil concentrations which can be detected by naked eye. We had a very interesting debate about this at this last ..." | Read more » over 8 years ago
Matej "HI Mary, I am not 100% familiar with methods of collecting oil from soil. I think @eustatic might know better. I saw he had some diluted soil sampl..." | Read more » over 8 years ago
marlokeno "@marlokeno- Great work, Matej- Do you have any thoughts on applying your research to collecting samples from frozen soil? How will frozen earth af..." | Read more » over 8 years ago