Using TLC for measuring quantities

[Ganoderma]

I am studying plants a fair bit now, and a current project is comparing certain plants' chemicals and quantities. I am fairly able to work with tlc plates and reagents, and identifying some of the chemicals (still working on this, but a lot has to do with just playing and comparing with others work and reference samples etc).

But one thing i am still struggling to comprehend is the analysis in getting the quantity using TLC . i know its not as accurate as other methods....but i have no lab so cost of columns and better equipment is a big limiting factor!

Anyone here have experience with this?

[Mercedes Benzene]

I've never had any experience with quantifying compounds using TLC since I've always had access to more complex equipment.
The only ways I can think of that would allow you to measure quantity from your TLC plate would be to:

1. Scrape off the spot, dissolve in solvent and measure by some other technique (like spectroscopy)
2. Use scanning densitometer

Unfortunately, these methods require access to a lab. I really can't think of any way for you to get an idea without more advanced techniques. Sorry.

[modest]

While I've done TLC before, like MB, I've never used it quantitatively. In case it might help, here's a google book source describing a method like MB says of scraping it off and using another technique (a colorometric technique):

Introductory Practical Biochemistry - Google Book Search

And, here's a whole book on Quantitative Thin-layer Chromatography:

Quantitative Thin-layer ... - Google Book Search

~modest

[Ganoderma]

well, thats a bummer explains why i cant find answers except with other methods....

i am certainly going to track down a copy of "Quantitative Thin-layer Chromatography and Its Industrial Applications" seems quite specific for what i want.


now that my original Q's are answered, heres another.

is there a method that i can do that doesnt require thousands of $'s for equipment.....my spending limit is low, like $500 USD....any thoughts on methods that are low cost?

thanks for th ehelp

[modest]

I bet you could find an old used densitometer for under $500. You'd just have to be sure to get the software to interface it with the PC and the instructions because I doubt any companies would be supporting a unit that's... maybe... 10 years old

Also, the book I linked in my last post (Quantitative Thin-layer Chromatography and Its Industrial Applications) discusses using a densitometer on plant extracts with TLC in chapter 10 "Assay of Bioactive Materials in Plant Extracts". Most of that chapter is available through the google book preview:

Quantitative Thin-layer ... - Google Book Search

~modest

[Ganoderma]

thanks again for all the info! i have been reading a fair bit on the topic lately, and i think i can manage column chromatography alright. so i got on google to get an idea of prices and am finding that many of these science supply stores don't list prices and require sign ups and such to even get a price list....whats up with that? I wanted to get an idea of columns and silica gels to compare with local places but seems not so easy lol...any have any idea why? these are not exactly drug manufacturing items i dont think....

[modest]

I'm not sure. My only experience with buying chemistry supplies is through a local supplier. you might go to google product search and search for "extraction columns" or "polypropylene extraction columns".

I'd be very surprised if you couldn't get prices without signing up... but I really wouldn't know.

~modest