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
pdhixenbaugh "@Matej Lots of interesting things here! Anecdotally from the spill response team I work with, it only takes a few drops of oil to create a sheen, s..." | Read more » over 8 years ago
mathew "the crude looks really clipped-- I know there's a dip in the middle but it is really topping out. " | Read more » over 8 years ago
warren "Thanks for your feedback! " | Read more » over 8 years ago
warren "I don't believe those are clipped - I increased the exposure until it just barely touched the top, but did not depress or deform the top of the cur..." | Read more » over 8 years ago
mathew "the 80W-90 looks a bit clipped in the blue: https://spectralworkbench.org/spectrums/55075 the crude is substantially clipped in the blue: https:..." | Read more » over 8 years ago
Matej "HI Guys, Thanks for your interesting comments! Jeff: I will certainly try to do that. In general I am trying to find out what could be a realistic..." | Read more » over 8 years ago
msysinfo "I need to measure oil concentration in a water mixture. Can a SPECTROMETER be used to measure the oil concentration? If it a solute that dissolves ..." | Read more » over 8 years ago
mathew "Awesome technique! the look of the 5w-30 reminds me of thawed out frozen diesel fuel. I think the milkiness in diesel from freezing is from wax cr..." | Read more » over 8 years ago
warren "Hi matej - are the differences in the 5w30 just by visual inspection or in the spectrum as well? " | Read more » over 8 years ago
warren "The embeds are working again. Thanks for your patience! " | Read more » over 8 years ago
warren "Sorry - for those using HTTPS/SSL, the embeds won't be working at the moment, as we just upgraded PublicLab.org to use extra security, but haven't ..." | Read more » over 8 years ago
Craig "Nice Work " | Read more » over 8 years ago
straylight "Good points and I understand how you feel, coming at his from a chemistry teachers viewpoint myself. I guess it depends on what experiments and dem..." | Read more » about 9 years ago
srpratt "I'm new to the cellphone-becomes-a-photospec phenomenon, as I was told about this by a colleague. As an AP Chem teacher, I'm looking for hacks to ..." | Read more » about 9 years ago
ichinarayan "ok thanks so much " | Read more » over 9 years ago
straylight "In spectral workbench, when you are looking at a spectra, there is an option to export and save the data in a variety of formats, including xml and..." | Read more » over 9 years ago
ichinarayan "wow beyond belief. i thought it was complicated listing program. and how do you exported the spectra image into csv form? thanks a lot " | Read more » over 9 years ago
straylight "Thanks for the question ichinarayan, I exported the spectra in csv form into microsoft excel. From there I selected the wavelengths I wanted to st..." | Read more » over 9 years ago
ichinarayan "what software do you use for your analisis program used to generated graph? " | Read more » over 9 years ago
Paquicamus "That is great. It's just like a double beam spectrophotometer. Any chance to post some results. For example a 10mg sodium nitrate aqueous solution,..." | Read more » about 10 years ago
mathew "Nice! I'm going to go print one tomorrow. " | Read more » about 10 years ago
warren "Wow, amazing progress! I love the photoshoot. Can you upload the sketchup files etc. in the research note as well? " | Read more » about 10 years ago
silverhammer "Hi, Thanks. Answers as follows: 1. Yes - kit does come with a color card. Its got 3 states. Control (orange), Pink (bad), Pink/Orange (so-so) 2..." | Read more » about 10 years ago
cfastie "Holy Mackerel. SCIENCE! This is a great use of the Public Lab spectrometer, and you are getting very good spectra with it. Does the RenekaBio ass..." | Read more » about 10 years ago