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Dr.3vil
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Home Made TLC plates
TLC plates are expensive, so, make your own.
giving credit where credit is due, original project by: allanf0
Attachment: Homemade TLC plates.pdf (473kB)
This file has been downloaded 15711 times
DR.3vil
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Paddywhacker
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Thanks for that. Spreading looks to be the trickiest part ... getting an even thickness.
A really interesting web site too.
I wonder if silica flour from pottery supplies would work.
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Siddy
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Thats excellent, thanks for posting it.
One thing, it says for spotting "place a small drop", and has a pic of a pasture pipette putting a drop on the plate - that gives you a huge spot and
large diameter that wont be accurate. so instead, heat the middle section of an empty pasture pipette in a hot Bunsen flame, as you do so apply stress
longitudinally, feeling for when the glass gets soft. When it is sufficiently soft (experiment to find this point, usually very soon after glass is
soft and bendy) withdraw from the flame and while each hand is on either end of the pipette separate your arms to there full length in one swift
motion. After a little practice you should be making very thin capillaries, about 1m's worth with every pipette, cut them up into about 5-10cm pieces
(score the outside of the capillary at 5-10cm intervals and then snap pieces off). They are reusable if you rinse them, which is tricky, but making
them is so much fun why bother?
To use, dip the capillary into solution, wait for the solution to raise inside (few seconds, it wont go all the way up, just get a cm or 2), withdraw
it and then lightly touch the end of the capillary on the plate to release the solution - be careful not to scrap plate - a very small volume of
solution has been spotted onto the plate!
Most analytes do not absorb in visible region, so a UV lamb (with correct eye protection) is good to use, or dip the developed plate in vanillin and
heat with a hair drier- some compounds make cool colors.
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Dr.3vil
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hmm, good point on the UV indicator. I have a set of lab quality silica plates with the florescent indicator, I wonder what It would take to
incorporate the same function onto homemade plates. (project # 6241.. there are
several texts on TLC at my university library so I'll take a look next time I'm there.
As far as coating is concerned, yes, the uniformity of the layers is going to be an issue. perhaps there is a DIY method that could be developed. with
a ball mill one should be able to get a fine enough grind which is key. Instucatables has a few DIY ball mills that can be fashioned from a power
drill and HDPE bottle. Maybe take a look at commercial coating system and see if we could copy one...maybe ultrasonic agitation of the sullery?
DR.3vil
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Sedit
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Would it be possible to turn this into a slip where the particals are suspended in the water so when the plates are put into it and the particals
settle they will be in a perfectly even coating?
Knowledge is useless to useless people...
"I see a lot of patterns in our behavior as a nation that parallel a lot of other historical processes. The fall of Rome, the fall of Germany — the
fall of the ruling country, the people who think they can do whatever they want without anybody else's consent. I've seen this story
before."~Maynard James Keenan
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DJF90
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I was thinking of making a "jig", with a groove the width of a microscope slide, but very slightly deeper (aluminium, made using a milling machine".
The "slip" could then be applied and a piece of aluminium or something drawn across the surface to produce replicable uniformity.
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watson.fawkes
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One of my first thoughts upon reading the project was about building a spin coating rig. You wouldn't need all the precision that's used in the semiconductor world, certainly. Likely a small-robot motor should be
adequate.
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DJF90
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That looks very nice. Couple of problems with that kinda rig:
> Hard to get replicable uniformity
>Will work rather badly using a rectangular substrate? In which case a circular disk should be used, meaning waste as you trim it to the proper
shape.
But it is a very attractive idea and can't be that hard to set up 
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watson.fawkes
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Uniformity comes from consistency of the
suspension, consistency of dispensing, and consistency of the rotational motion. Certainly you'd get consistency with a single batch of suspension,
shaking the dispenser each time. Put down an excess of suspension in the center each time and it will spread to the edges, even the long ones, just
fine. At question with a non-circular shape is how much suspension gets spun off. That matters little, as you can collect it and reuse it. As for
consistency of speed, use a small microcontroller (like Arduino) and program in a consistent spinning cycle.
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Dr.3vil
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I think Watson is right on with the physical properties of the suspension. the quality and consistency of the material is 50% of the problem.
With regards to application, I think spin coating should be replaced by screen- print/Masking application. Spin coating is great for fluids of low
viscosity, but will it be able to handle the thick slurry?.
A process whereas the substrate (microscope slide) is masked by a material of known thickness (plastic sheet maybe, several layers of tape). There is
a hole in the mask according to desired width and height of the chromatogram. Absorbent/binder suspension is applied to the top of the mask and with a
strait edge made level. allow to cure, remove mask, activate and use
sound like a plan?
DR.3vil
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watson.fawkes
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It works
better with higher viscosity suspensions. The thickness of the coating depends on a ratio between viscosity (internal cohesive forces) and
centrifugal force from the spinning. Higher viscosity liquids can be spun out with more control.
As aside: Centrifugal force is not fictitious, as often labeled. It is, however, frame dependent. When looking at the forces on the suspension, you're
in the frame of reference of the liquid, not the spinner. From the point of view of the liquid, it experiences centrifugal force.
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Dr.3vil
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I don't have any experience with spin coating but I accept your reasoning. Looking back DJF90 mentioned a bit about milled aluminum templates, I could
see that as being a viable means to build a spin coat rig. round rig with a cut-out for the substrate. It would be conceivable to have several rigs
for various sizes of plates. time to build something i guess..
DR.3vil
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watson.fawkes
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Quote: Originally posted by Dr.3vil  | | DJF90 mentioned a bit about milled aluminum templates, I could see that as being a viable means to build a spin coat rig. round rig with a cut-out for
the substrate. |
Other ways of constructing the holder are bent-up tabs on all four sides (for, say, a
microscope slide) or, alternately, four strips of brass silver-soldered to a face plate.
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Eclectic
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http://www.emdchemicals.com/lifescience/literature/061009_Ma...
http://www.sas.org/E-Bulletin/2003-04-18/labNotesAS/
http://books.google.com/books?id=ega5c11VHvkC&pg=PA821&a...
[Edited on 6-15-2009 by Eclectic]
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Paddywhacker
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There is a thread over on The Vespiary:-
http://www.thevespiary.org/talk/index.php/topic,33.0.html
on making microcrystalline cellulose. That substance might make a good TLC coating.
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Eclectic
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http://www.freepatentsonline.com/3607777.html
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Cloner
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An even coating of TiO2 for dye sensitized solar cells has been made using the "doctor blading" technique. The substrate is a microscope slide. On
either side, a straight ridge is formed by scotchtape in one or more layers. The gel is brought onto the substrate and then spread with the straight
backside of a scalpel blade (but anything straight should do). Due to the tape, the area in the middle receives a very thin layer of suspension.
After heating, the resultant layer is very even in thickness. If it works for TiO2 then it should work for a gypsum/silica mixture just as well. The
thickness can be controlled by the thickness of the tape layer.
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Sedit
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Im currently attempting to make some TLC plates out of clay and I wanted to know if there was any reason why I don't really see ceramic TLC plates on
the market.
Is it because its simpler to prepair them with Silica and a binder, limitations in constructing them on a large scale or is there some chemical reason
for not making them.
Im making mine from a clay slip, I mixed it well with water to make it runny then allowed it to settle a bit before decanting the finest of clay still
in suspension. I then placed it on a piece of plaster board and tried a couple different methods. One I just poured onto the board and plan on
trimming later on. The surface tension assures that there is an even coat along the entire surface. I also coated a microscope slide but im pretty
sure this is going to curl up on drying making it worthless. The others I tried pouring the slip out and letting it set for a variety of times to
setup and then placed microscope slides on top to prevent the issue of curling which is a result of shrinkage in the clay. The microscope slide should
cause the water to be sucked out evenly instead of allowing evaporate which if uncovered would cause the edges to dry at different rate forcing it to
curl and crack as it dries. When its done im going to fire them and hope they do not curl in the kiln as well.
What do you all think? Will they work as I expect or no?
Knowledge is useless to useless people...
"I see a lot of patterns in our behavior as a nation that parallel a lot of other historical processes. The fall of Rome, the fall of Germany — the
fall of the ruling country, the people who think they can do whatever they want without anybody else's consent. I've seen this story
before."~Maynard James Keenan
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smuv
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Clay wouldn't be good. It contains mostly the oxides of silica and alumina. What you want is polymers/oligimers of silica which have some free OH
groups. If you want a truly OTC way, find some clean sand, dissolve it in sodium hydroxide, filter, and prepare the silica gel from the sodium
silicate solution you have made.
But let me say, I thought about making TLC plates for a long time, finally I broke down and just bought them. They are aluminum backed and have a
short wave UV inidcator, I spent some money on them, but I don't regret it for a second. If you ration your plates, 20 sheets (standard box size) can
give you hundreds of TLCs. Look around on ebay and you can get good deals.
If you are in the US I have a box of 20 glass backed alumina plates with a shortwave fluor (meant for prep TLC, but will be more than adequate for
tracking reactions), I would sell them for 30 bucks + shipping (think twice though, aluminum backed plates are sooo much more convenient).
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Sedit
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Well after firing it would be a fine crystal structure of the oxides intermeshed with Mullite but im still not sure if that will make a difference
because like you said already would pretty much be a charge zero complex and not have the OH needed.
The reason I want to make my own is to experiment with various imbeddings like you already mentioned such as the UV reactive ones or possibly
imbedding things like Ferric chloride for amine detection and things of that nature. I would like the ability to play with various formulas for
various projects and buying them just wouldn't have that same appeal all cost aside.
However I am considering your offer and you will recieve a PM from me tommorow. I want to play with the formulas but its always good to have a
standard around for comparison.
Knowledge is useless to useless people...
"I see a lot of patterns in our behavior as a nation that parallel a lot of other historical processes. The fall of Rome, the fall of Germany — the
fall of the ruling country, the people who think they can do whatever they want without anybody else's consent. I've seen this story
before."~Maynard James Keenan
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smuv
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Take your time. Really, if you want to get a glass cutter and practice on some glass panes before you commit to buying these, go for it.
Let me tall you a little more about these:
I bought them for $30 dollars from a vendor selling surplus lab stuff on ebay over a year ago. It was a box of 25 plates, 5 have been used. The
plates are in good shape.The glass is about as thick as a quarter. Their dimensions are 20x20 cm; they are alumina coated, with a 254nm fluor and the
stationary phase is 1000 microns thick.
Most standard TLC plates have ~250 micron stationary phase, these plates have a thicker stationary phase, for prep use. They will preform equally
well as standard plates, again the only difference is they allow more product to be loaded before they start streaking/giving poor seperations. As an
aside, for prep work you could purify of about 1-2g of material per plate (assuming 5mg per sq cm which is about the loading ceiling for a 1000u
plate). Pics attached.
Also: I have never heard of adding ferric chloride for amine detection, but in the past in order to determine what spot is an amine, I have taken my
TLC sample, and seperated an aliquot. This aliquot I treated with a tiny amount of HCL gas (taken by using a pipet to suck a couple of times some
HCl vapor from the head-space of a conc. HCL bottle). Run the HCl treated and stock sample side by side. In the HCl treated sample the HCl salt will
stay at baseline except in VERY polar solvent systems (eg neat methanol or water). So whatever spots are missing or have become very faint (from
incomplete neutralization of the amine) when comparing the two samples are very likely amines (or compounds that could react with HCl...).
 
[Edited on 2-9-2011 by smuv]
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peach
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This is a great thread!
I was thinking of spin coating as well. I've seen people doing it, not with TLC's but with other thin films, using a computer fan - which is easy to
control and smooth running, and cheap, or free. I was also thinking, like Smuv says, that it's not such a bad thing if they're a bit thicker, since
they can be useful for preparative. The PDF is very nice. Although yes, spotting with a pasteur, as it is, is likely going to make a mess. You can see
in the last picture, the plate on the left is not the eluted plate on the right - which he does mention.
There is a thread going here which discusses spotting tools and gathering results with software.
The only drawback to DIY plates or column packing is the difficulty in comparing them with the Rf results you'll find quoted, which are all on
standardised grain sizes, purities, layer thicknesses and uniform.
250 microns though... you can get a rough check of that with a cheapo micrometer.
If you had access to a microscope, you could have a peak at the grains through that. Alternatively, there are quite a few places online selling foot
square swatches of micronic weave cloth - including stainless. Attach a big vibrating sex toy, and you've got a screen for the particle size.
I have posted a photo of it before, but I have made a little ball mill using Lego alone. The uses of Lego never end. It was simply a medicine bottle
sat on top of some of the rubber wheels and driven by a motor. Marbles inside provided the grinding action. You will certainly want it running from a
power supply, because it's going to be on for a looooooooong time to get it that finely divided and homogenised. Maybe go the whole hog and build a
Lego spin coater whilst at the forge. You could use the MindStorm controllers to produce repeatable results.
For the price of the TLCs new, if you've got a micrometer and a bit of Lego handy, it's worth doing!
Try new micronic stainless weave bedding! Pressure cleaner friendly. I was going to suggest stockings, or silk, but those will probably deform too
much and the stainless is going to have a better rating on it, as it's usually going into a filtration system of some sort to begin with.
[Edited on 9-2-2011 by peach]
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Steve_hi
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Here is a link for a youtube video by the home scintist, Author of
"Illustrated guide to home chemistry experiments" by Robert Bruce Thompson. Making home made TLC plates.
http://www.youtube.com/watch?v=pNDQkM3jasA
video # 24
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peach
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I think that's a commercially made TLC.
MIT has some very good videos on their site, free of charge and open to the public!
<iframe sandbox title="YouTube video player" width="480" height="390" src="http://www.youtube.com/embed/e99nsCAsJrw" frameborder="0"
allowfullscreen></iframe>
<iframe sandbox title="YouTube video player" width="480" height="390" src="http://www.youtube.com/embed/ml58GCq078o" frameborder="0"
allowfullscreen></iframe>
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Chordate
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Would anyone here want to some TLC plates? I know that making your own is cool, but I think I have a sealed box of 500 2x4 sillica on glass plates in
a box somewhere. I could go looking for it if someone was interested, as i certainly don't need that many.
EDIT: thats 2 inch by 4inch, 5cmx10cm
[Edited on 5-3-2011 by Chordate]
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