hi ,
it is known that thin layer chromatography is not suitable for quantitative analysis of components in an unknown compound but does anyone knows the exact explanation for it??
2006-09-26 21:00:19 · 6 answers · asked by Anonymous in Science & Mathematics ➔ Chemistry
To put it very simply, when you are essentially doing a footrace of molecules in a solvent. The more they like the solvent vs. the solid plate, the farther they will travel. The problem for quantitation is that the result is a spot of material contained in a solid matrix. First you need a way to see this spot to identify it's there (color, stains with iodine, etc), then, if you wanted to quantify how much there was, you would need a technique to do this. You'd need to be able to quantify it, but, as it's contained in a solid matrix it can't be weighed and quantitation from darkness of a spot is highly inaccurate (called colorimetric techniques, though they are sometimes used). Lastly, the spot actually gets broadened as it travels, so complete recovery is difficult as well.
2006-09-30 20:29:26 · answer #1 · answered by T.M.I. 2 · 0⤊ 0⤋
Thin layer chromatography(TLC) is a technique to find the dyes in a specimen.It is used in forensics to identify a certain piece of clothing be cause paint or dyes differ in chemical composition, even the ones that are supposed to be completely similar. This usually does narrow the range to a much smaller amount.
2006-09-27 04:09:02 · answer #2 · answered by Kixx 1 · 0⤊ 0⤋
Previous answer was dead on. . . but also realize that when performing a quantitative analysis you will compare result of an unknown sample to a known standard amount. In thin-layer chrom, you will see the bandwiths which "may" indicate amount of substance but you will not be able to assign a specific amount to component.
2006-09-29 16:05:17 · answer #3 · answered by mommaddz 2 · 0⤊ 0⤋
this is because the TLC is principally made to know how many compounds are there in a mixture. The number of components is determined by the number of spots that will appear on the plate and you use only a very small amount of the sample here. these compounds are separated by means of their reaction on the solvent. thus you will only know how many components are there in a mixture and not the concn of the components.
best answer?
2006-09-27 04:11:13 · answer #4 · answered by teroy 4 · 1⤊ 0⤋
Not true. It is difficult to use TLC quantitatively due to the small amount of material involved, but it can be done.
2006-10-01 03:34:27 · answer #5 · answered by yupchagee 7 · 0⤊ 0⤋
no
2006-09-27 04:01:50 · answer #6 · answered by Angele' 3 · 0⤊ 0⤋