Oil Testing Kit -- discerning 5W30 20W30

by gretchengehrke | almost 9 years ago | 2 | 2

What I want to do

I am taking spectra of the five oils in the Oil Testing Kit, and I forgot to label one of the cuvettes. Based on color, I could not determine if it was 5W30 or 20W50, so I compared the fluorescence spectra with hopes that they would have different lambda-max values.

My attempt and results

All three of these spectra were taken using a Blue Ray 405nm light for excitation, moderate light attenuation, and calibration based on the spectra of my white front bike light. The spectra have been smoothed and the peak heights have been equalized.

The spectra between the known 5W30 and 20W50 are sufficiently distinct, and the unknown aligns with 20W50.

Questions and next steps

How repeatable is this resolution? How comparable will the spectra be if I calibrate using a different white light? How will they compare if I dilute them? Will I be able to observe two peaks at the appropriate lambda-max values if I create a mixture of the two oils?

Why I'm interested

We want to know the precision of the spectrometer and our ability to discern different grades of oils in the real world. We're starting with neat samples and moving to mixtures and real environmental samples.

https://spectralworkbench.org/sets/show/2436

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Sprint Fellowship Application: Aquatic hydrocarbon sample preparation for Oil Testing Kit

by Shannon | about 9 years ago | 0 | 1

Application due: May 27, 2015
Dates of Fellowship: mid-June to mid-September 2015
Location: Remote, with preference for Portland (OR), Boston area, New Orleans or Raleigh-Durham
Fellowship stipend: $3,000 USD

This research fellowship involves methods development to enable the analysis of oils in environmental aquatic samples using the Public Laboratory spectrometer, largely focused on sample preparation. It is anticipated that adequate sample preparation will involve sample concentration and solvent switching. Methods used will need to be replicable by citizen scientists without access to laboratories, and therefore should avoid hazardous chemicals and utilize widely available, low-cost equipment. The successful fellow will design and conduct sample preparation experiments, document experimental results, and write protocols for appropriate techniques.
The fellow should have a background in chemistry, with environmental chemistry and analytical chemistry experience preferred. The fellow should have experience conducting independent laboratory-based studies and be familiar with data quality assurance and quality control metrics. The fellow will work closely with the Data Ambassador and the Director of Production throughout the fellowship tenure, and will have support particularly in study design, material sourcing, and trouble-shooting.

Successful completion of this fellowship will produce:

A robust sample preparation method for aquatic oil samples for analysis by the Public Laboratory spectrometer.
Written documentation of trial methods, denoting successes and failures.
A comprehensive portfolio of spectra from experimental sample analysis, annotated and uploaded to Spectral Workbench 2.0.
Integration of procedural wiki pages with Spectral Workbench 2.0 (e.g. through pop-ups or wizards).
Coordination with three contributors to independently test the developed methods.

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Sprint Fellowship Application: Public Lab Beta Oil Testing Kit

by Shannon | about 9 years ago | 0 | 2

Application due: May 27, 2015
Dates of Fellowship: mid-June to mid-September 2015
Location: Remote, with preference for Portland (OR), Boston area, New Orleans or Raleigh-Durham
Fellowship stipend: $3,000 USD

This fellowship will focus on the evaluation of the Oil Testing Kit capabilities. There are two primary components of this fellowship: (1) to determine the accuracy with which the prototype Oil Testing Kit spectrometer can measure oil reference materials, and (2) to conduct and synthesize results from a multi-user beta-testing program measuring known and blind samples, evaluating precision and utility. For the beta-testing program, the fellow will develop written methods for users to analyze samples, and assess uploaded user spectra for accuracy and precision. Additionally, the fellow will assist in the identification of research partners to participate in the beta-testing program and independently analyze using commercially available spectroscopy equipment. From the beta-testing program and independent assessments, the fellow will produce a report characterizing the accuracy and precision of the Public Lab Oil Testing Kit tools and methods, and assessing the ability of the Oil Testing Kit to quantitatively distinguish a variety of oil types in the field.

Output 1: Coordination and management of the beta-testing program.
Output 2: A comprehensive portfolio of spectra from experimental sample analysis, annotated and uploaded to Spectral Workbench 2.0.
Output 3: A series of research note and a comprehensive report, leading to a coauthored peer-reviewed paper.

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can a surface sheen be collected for oil testing?

by mathew | about 9 years ago | 1 | 4

image by by Cesar Harada CC-BY-NC-SA

Can an oil slick be picked up off the surface and concentrated in to just oil? I did a suggestive early experiment using PIG Mats, a cheap oil-only absorbent mat for industrial usage. They are made of non-woven polypropylene.

I poured a little vegetable oil on top of a small container of water, and then swished a piece of the PIG Mat around. It picked up the oil but not the water, as advertised.

I was able to wring the oil back out of the mat.

Will this work with crude on an ocean surface? Maybe! Any thoughts on how to run a test ethically are much appreciated!

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Assembling the Oil Testing Kit Cuvette Frame

by mathew | about 9 years ago | 7 | 2

This cuvette frame's design notes are here, along with previous versions and other design ideas. It can be used with this procedure

Download and cut out all the five pieces:

all-together-9-8.511.pdf

all-together-9-8.511-2.pdf

I recommend a card stock like a cereal box. lines can be scored with hard presses of a pen, butter knife, or other smooth blunt thing.

Start with the main frame piece and pre-crease the folds:

Slide the long tab through the opposite side wall, and then tuck in place:

The long strip with triangular holes should be folded up like this:

Don't completely fold up this little part, just fold along the length-wise fold:

put it together by putting the M-folded sheet into the box, and sliding the V-folded strip through the center. Make sure the matching rectangular cuts are on the correct side, so that we can slide the laser attenuator in place.

That rectangular cut in the V-folded strip can get caught on the last little push through. watch it.

The last centi meter is the hardest to get through.

once through, push the tabs in place on both sides:

Alright, the frame is almost done! Now to put the cuvette holder in place.

Pre-fold the cuvette holder:

This fold is the trickiest. Push inwards on the center section while folding. It will pop in place. Crease all the way flat:

Now lets put it in the frame:

fold the bottom flap up and through, and slide the front of the cuvette holder down on it:

Now close up the other end of the frame:

Now assemble the laser attenuator:

Place in front of the spectrometer, add cuvettes and a 405nm laser pointer, and you're done:

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Designing an Oil Testing Kit Cuvette Frame

by mathew | about 9 years ago | 7 | 4

I’ve been working to design an oil testing add-on the the spectrometer 3.0 incorporating the feedback from @stevie, @warren, @stoft, and others regarding the current oil testing kit and spectrometer.

The design is requirements are to unite a 405nm laser pointer, a container for oil, and the spectrometer such that easily repeatable measurements can be taken.

The features the kit needs to have are:

a method or container for keeping the laser’s light path through the sample consistent
a means of lining up the laser with the collimation slit and sample so it stays in place.
a means of controlling the brightness of very bright fluorescences.

I also wanted a fourth feature— the add-on should be made out of pieces of paper that can be printed and cut at home.

Design process

I worked almost entirely on paper, producing flat vector illustrations in adobe illustrator. I cut about half the prototypes out by hand, and the other half on a laser cutter.

Some prototypes & sketches:

I started with some 1cm square graph paper from the Open Structures project.

I then turned those into vector files, printed them out, and cut with an craft knife onto thicker paper underneath, and made scores for folding with a butter knife.

Oil Containers

We haven’t found a cuvette or small container which is at once:

affordable
leak resistant
has a consistent light path
isn’t melted by volatile hydrocarbons

Small cast glass containers for nail polish and the like don’t have flat sides and so the light path changes, and glass cuvettes are prohibitively expensive. Cuvettes are designed to have consistent light paths for optical measurements. This beautiful round-lidded cuvette is almost perfect. But its made out of polystyrene, and diesel, crude, and other products melt the cuvettes. Notice the droplets dripping through the middle:

Most cuvettes are square, and have square lids. We have found that all the square lids leak. They’re terrible. But… they don’t melt and the light path is consistent. so I designed around an acrylic cuvette that costs $0.25 each. This is the biggest problem with the design. If you can find a round-lidded acrylic cuvette please tell us. Leaky cuvettes leaking:

Lining up the laser

Building a frame out of paper that holds the laser rigidly was a bit challenging, as we’re using a laser pointer for consistency of packaging and its low cost. This means the button is on a tube, and usually requires some force to press. The frame needs to elevate the laser to the collimation slit of the spectrometer and not deform when the button is pressed. I tried two different strategies based on triangles, and settled on an interlocking triangular frame in a box that is very rigid.

Five significant prototypes:

Brightness control

previously, we’d diluted the samples to control for brightness of fluorescence, which isn’t the best strategy, as dilution is time consuming and error prone. I switched, at @stoft’s suggestion, to a gradient slider in front of the laser. It can be printed on an acetate transparency sheet.

Connecting to the spectrometer

I went through a couple of strategies to connect directly to the spectrometer but have removed them from this version. This makes for some instability. Flaps that slide into the front side of the spectrometer (rectangular ones) were the most effective, but pulling them in and out was hard and could damage the geometry. I'm not settled on leaving the two parts disconnected, but the frame does work in its current state.