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Topic: Paper Chromatography discussion on an example on sample of Ink  (Read 16251 times)

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Offline MarZ

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Paper Chromatography discussion on an example on sample of Ink
« on: September 12, 2009, 08:18:31 AM »
I am experimenting on a sample of ink and trying to find its components with Paper Chromatography. The results are not typical and would like your opinions and comments. I am posting images of the results for discussion.

I would like to know what would be the components' zones (I gave my suggestions in dotted grey) and from which part of the zone the mesurment should be taken to calculate (estimate) the Rf values.

I will be doing more runs today.


Offline MarZ

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Re: Paper Chromatography discussion on an example on sample of Ink
« Reply #1 on: September 13, 2009, 12:11:27 AM »
Hmmm.. seams this post did not draw the attention of many.  I ran the sample with gradual concentrations of Propanone and got better and neater results.

Seems evident that there is Black, Cyan and Violet dyes, but the question is if there are one or 2 different violet dyes almost merging in each other. 

Opinions welcomed

Offline MrTeo

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Re: Paper Chromatography discussion on an example on sample of Ink
« Reply #2 on: September 13, 2009, 07:22:31 AM »
As a premise I'd like to say I'm not really into this field... so my answer is only supported by personal experience.  ;)
I did a similar trial some time ago even if only qualitatively, using ethanol too and I got some interesting results... personally I'd say that there's only a violet dye dispersed with different density on the paper used. What do you think of using thicker paper (making the separation process slower)?

Here are my results (from the left: blue,red and black pen ink)



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Offline MarZ

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Re: Paper Chromatography discussion on an example on sample of Ink
« Reply #3 on: September 14, 2009, 04:19:53 PM »
Thanks - I am glad that I found someone who have tried this.  I am using a normal thickness chromatography paper (I think 0.18mm) and I can find a thicker version 34mm from local supplier.
 
I just wish to have more compact zones for a start.

You got nice zones there mate. I have tried blue ink and I got same results Violet+cyan. It seems standard mixture in most blue ink. I did some tests on the Violet dye and might be Methyl violet (just an idea not a conclusion!).

Regards my experiment I have mixed opinions. On one hand I think that there is one violet dye dispersed (why a company put 2 different dyes of same colour in the mixture?) On the other hand, if one studies the pattern with diff conc of propanone, there appears to be a strong violet (upper pat of zone in 80%,70% ; lower in 50%) and another faint dye which appears mostly in 50%. above the stronger dye,

If I have to decide, I would say that there is one violet, once cyan and one black residue which I wonder what it is since no solvent did really moved it along the staionary phase as a distinct zone - it is always an elongated streak from the origin.

I also wonder from where I should measure to calculate the RF value. Seems nobody knows if it is from the centre, from the top, denser part of zone, etc...












Offline Borek

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Re: Paper Chromatography discussion on an example on sample of Ink
« Reply #4 on: September 14, 2009, 05:03:09 PM »
Thanks - I am glad that I found someone who have tried this.

I did the same back in seventies, you would be surprised how similar my results were :)
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Offline DrCMS

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Re: Paper Chromatography discussion on an example on sample of Ink
« Reply #5 on: September 15, 2009, 06:52:10 AM »
The dyes I've seen used for this are crystal violet, methyl violet and victoria blue.  Methyl violet is typicaly not a single material but a mixture of at least 3 dyes (one of which is crystal violet)

Regards my experiment I have mixed opinions. On one hand I think that there is one violet dye dispersed (why a company put 2 different dyes of same colour in the mixture?)

Because that is what is commercially available, whey spend time and to separate the dyes if you do not have to.

Offline MarZ

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Re: Paper Chromatography discussion on an example on sample of Ink
« Reply #6 on: September 15, 2009, 04:45:24 PM »
Thanks for all the info esp for names of  such commercial dyes.  I have carried out some 20 tests trying different solvents and concentrations. I have concluded that there are 2 different violets, a cyan, a black and a possible pale yellow. (See Pics attached)

Today I went to buy Acetonitile  but was too expensive so instead I bought DiMethylSulphOxide ( aka DMSO). Tried it 50% inwater but not very good results (more last tests tomorrow)

Do you agree with the 5 dyes present hypothesis?

If I use thicker (3mm) chromatography paper, would I get better results ?



Offline MarZ

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Re: Paper Chromatography discussion on an example on sample of Ink
« Reply #7 on: September 20, 2009, 05:47:16 AM »
For the Chromatography freaks - here is an account of the paper chromatography tests carried out on the sample of ink discussed in this post

http://www.marz-kreations.com/Chemistry/Chromatography/Inks/Ink02.html

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