safe thin layer chromatography in the home

According to one of the lab books I'm reading, namely Gottfried Bringer's
"A laboratory manual for organic chemistry", p.37, one can use sugar and starch
as adsorbents for chromatography. On p.45, he says one can do thin layer
chromatography on microscope slides. On p.38, he says one can use water,
ethanol and methanol for chromatographic solvents. So, it appears that
one can at least prepare TLC plates using safe materials commonly found
around the home.

Regrettably, none of the chromatography experiments described in the book
actually use water, ethanol or methanol for the solvents.

Water will dissolve sugar but I don't know about the solubility of sugar
in ethanol or methanol, nor of starch in any of them. Maybe gelatin would be
a better adsorbent. Maybe another possible adsorbent would be made by taking
old coffee grounds, reuse them until they no longer color hot water that passes
through them, and then dry them and regrind in a coffee grinder until they
are as fine as possible.

In Gottfried's description of the preparation of chromatographic plates,
he emphasizes that the adsorbent must be very finely powdered (which
I've addressed above in the case of coffee) and needs about 5 percent of a
binder such as CaSO4 to stick to the plate. I'm wondering whether
confectioner's sugar is fine enough? I don't know aobut CaSO4 in the home,
unless it is available as plant food or something. What are some other binders
one can use that are commonly found around the home, particularly the kitchen.
Here again, gelatin occurs to me since I think it is basically just glue.
I'm not sure what kitchen utensil one would use for an applicator.

After all that, what kinds of substances in the home can one expect to
separate with TLC on a microscope slide, with water, ethanol or methanol
as solvents and with the kinds of adsorbents described above?

Ignorantly,
Allan Adler
[Only registered users see links. ]

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"Allan Adler" <[Only registered users see links. ].mit.edu> wrote in message
news:[Only registered users see links. ].mit.edu...
starch
be
taking
passes
binders
kitchen.

There are many books on "kitchen chemistry", and most will have experiments
on paper chromatography. I've set up experiments for students by printings
a row of dots of various colors on sheets of chemomatogrpahy paper (filter
paper could also be used) with an inkjet printer. Rubbing alcohol is a
useful eluent; it is a 50:50 mixture of isopropyl alcohol and water.

Allan Adler <[Only registered users see links. ].mit.edu> wrote:


CaSO4 in a particular form of hydration is also known as "plaster of
Paris." In the USA this is available in almost any decent hardware
store and also often in craft stores.


At the first level, you're going to be limited by what you can see;
i.e., the components of your analyte must be colored for you to detect
them visually. (In synthetic chemistry this is almost never the case,
and additional techniques must be used to visualize colorless
compounds.) Therefore you will want to look at colored things: food
colors, ink pen spots, clothes dyes, stains... Do not be limited by
what is available as a preformed pigment; you can also extract
mixtures of colored compounds from many plants. Use your imagination.

Steve Turner

Real address contains worldnet instead of spamnet

Steve Turner wrote:


Or fluorescent things, like laundry detergent.

If the substrate is itself fluorescent, like many white
papers, you can sometimes visualize a molecule
by its ability to quench UV -- it forms a dark spot,
which is called a quench spot.


In my experience, the sort of person who needs
to use their imagination does not benefit from
being told this.

On the other hand, "Be Creative" is a slogan
that works every time! :-)

Mark Thorson <[Only registered users see links. ]> wrote:


Yes, good point. This technique is used all the time, with TLC plates
that have a fluorescent material added to the absorbent. I've never
actually tried this in paper chromatography. I don't think that the
papers ordinarily used for this have added fluorescent brighteners.

Steve Turner

Real address contains worldnet instead of spamnet