Cellulose TLC separations at home (Part I)

Thin layer chromatography (TLC) is a quick and easy analytical technique for separating chemical mixtures into their constituent fractions.  It has advantages over paper chromatography, including ease of use, reproducibility, and speed.  There are well-described ways to make TLC plates at home from common materials, including starch and chalk.  However, chemists routinely use cellulose TLC plates to separate hydrophilic compounds, so it would be great to be able to make these at home.

As such, I present the first in a series of how to make your own cellulose (and hopefully some reverse-phase) TLC plates at home with stuff you can grab at the grocery store.  Part I (this page) describes how to make microcrystalline cellulose and how to cast TLC plates with it.  Part II describes how to extract dyes for staining the plates, and Part III will describe attempts to acetylate the cellulose and make reverse-phase TLC plates for separating other compound classes.

Part I:  In which our intrepid hero discovers how to cast cellulose TLC plates at home

I came across this awesome PDF of how to make microcystalline cellulose from cotton balls soaked in dishwasher detergent and diluted acid, all of which you can acquire at various stores (PDF reposted from here).  The author of this PDF then casts TLC plates using this cellulose powder.  Note that hydrochloric acid is also known as muriatic acid, and although it’s getting harder to find, Lowes still has it as of this writing.

*SAFETY NOTE!!!*  Muriatic (hydrochloric) acid is sold in concentrated form and will cause severe burns if it contacts your skin or eyes.  There are also bad effects if the vapors are inhaled.  Treat this stuff with respect.  Kids should always have an adult work with acids and bases, and these adults must use gloves and safety goggles when handling them.  Also please work in a fume hood or at least under your range vent.

Making these plates is a great activity for students to do as part of learning about polymers, chemistry generally, and analytical science.  I would recommend separating things that inform us about our world around us.  Things that spring to mind include amino acid supplements, various protein powders for bulking up, different kinds of DNA, etc.  In this case, the solvent to elute with (the mobile phase) would be one with some nonpolar or hydrophobic character.  Various strengths of vinegar, nail polish remover (acetone) and rubbing alcohol (isopropanol) in water would be good ones to try.

To detect separations of non-colored analytes, you will need to stain the plates after separation.  Part II describes some techniques to try for this.


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