alchemizt
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Building a solubility tester with arduino chip
I want to build a device which determines solubilities of samples in organic solvents. I'm contemplating how to do that. I'm thinking that with a
photometer and light source, you should be able to plot a dissolution curve due to the mixture becoming gradually more translucent as there are less
and less undissolved particles in there, and eventually should be able to record the point at which the solvent becomes saturated as the change in
translucency tapers off. You could calibrate an arduino chip so it knows the spectral properties of a saturated solution of your sample in the given
solvent and use the dissolution curve to determine how much of the sample dissolved in a given amount of solvent.
What do you think?.
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Sulaiman
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I think that ;
You will need a calibrated temperature measuring device
You will need temperature stabilisation
(or solubility vs. temp. data)
You need good stirring
So, stirring would keep particles suspended,
which I guess would reduce transmitted light
Making or buying reference solutions sounds tedious and/or expensive.
CAUTION : Hobby Chemist, not Professional or even Amateur
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RustyShackleford
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Sounds very doable and the ideas you have seem reasonable. As Sulaiman said i think having integrated temperature control and stirring will be
necessary to get reasonable data. If you plan on using a test tube or such as the container, then for the stirring i think a vortex stirring mechanism
would be perfect, should be really easy to build yourself.
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Sulaiman
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PS if you use a visible laser you can see when there are any suspended particles.
(I forget the name of this effect)
CAUTION : Hobby Chemist, not Professional or even Amateur
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alchemizt
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Quote: Originally posted by Sulaiman  | I think that ;
You will need a calibrated temperature measuring device
You will need temperature stabilisation
(or solubility vs. temp. data)
You need good stirring
So, stirring would keep particles suspended,
which I guess would reduce transmitted light
Making or buying reference solutions sounds tedious and/or expensive. |
Yeah the temperature part is a bit tricky, I'm thinking to connect a thermocouple to a PID controller programmed to keep the temperature constant. I
don't know how to do this in the case of exothermic dissolutions, not sure how to electrically cool the liquid. It can wait for the mixture to cool
back down to the test temperature before recommencing recording data. Then the possibility of supersaturation needs to be factored in somehow.
Stirring at a steady RPM will definitely will be necessary to keep the suspension uniform. Over time it would be possible to add a lot of data to a
database that would be useful for machine learning and making extrapolations.
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alchemizt
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| Quote: Originally posted by Sulaiman | PS if you use a visible laser you can see when there are any suspended particles.
(I forget the name of this effect) |
Is it the Tyndall effect?
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alchemizt
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| Quote: Originally posted by RustyShackleford | Sounds very doable and the ideas you have seem reasonable. As Sulaiman said i think having integrated temperature control and stirring will be
necessary to get reasonable data. If you plan on using a test tube or such as the container, then for the stirring i think a vortex stirring mechanism
would be perfect, should be really easy to build yourself.
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Is a vortex stirring mechanism the one where the machine shakes the tube in a circular motion like the ones they use in microbiology labs? I've never
tried that method of stirring. I was thinking of using a magnetic stir bar because its easy to find a hotplate stirrer and set it up to hold the
temperature constant. The only thing is the stir bar blocks light so the laser will need to be either above it, or else the chip needs to be
calibrated to know exactly how much light it blocks during a given time interval, that should be easy since at a high RPM it will be relatively
uniform. Can you control the temperature easily with a vortex stirring mechanism? Would you need to use an immersion heater? Like a cartridge heater?
I think it will be necessary to submerge the thermocouple in the solvent, because if you were to submerge it in a sand or water bath, you can only
really measure the heat going into the mixture, not whats coming out of it.
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Tsjerk
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Maybe put the thing in an insulated box? That way you can control the temperature as a whole. Also light from outside would be blocked which could
interfere with your readings.
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JohnnyBuckminster
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I have used an old commercial turbidity meter, I think it came from Fischer, to check the solubility of some dyes in various solvents.
My main concern was always the quantity sample required for a mesurement vs cost, it may be attractive to design something that can work with small
volumes, like 100 - 500 uL.
Heating and cooling might be achived with a Peltier element.
There are some DIY projects on YouTube, see for example
https://www.youtube.com/watch?v=Bu8y-6Bpv0U
In my experience with dyes, the stirring was actually not that important. If the sample did not dissolve properly, then there was always some
scattering stirred or not, and further dilution was required.
[Edited on 2022-6-2 by JohnnyBuckminster]
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DraconicAcid
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What kids of samples are you looking at? I'm just thinking of the tendency of many organic compounds to form supersaturated solutions until
crystallization is induced.
Please remember: "Filtrate" is not a verb.
Write up your lab reports the way your instructor wants them, not the way your ex-instructor wants them.
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DocX
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interesting! One should probably be able to do the same with melting point determination. Laser through capillary tube filled with salts, measure the
intensity, plot melting point.
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