Chromatography of plant pigments

TLC, done properly, produces a better result (see above) than paper chromatography - at a substantial price premium. I suspect the latter is all that matters to many HODs/School managers.
It doesn't have to be at a significant price premium. We microscale it, as per CLEAPSS, I reckon the single box we bought two years ago of TLC plates, which I cut into 6cm x 1.5cm strips for use in sample bottles, will last us for probably another 3 years! The kids usually get reasonable results: This was comparing green and coloured autumn leaves.TLC of autumn leaves.jpg
 
It doesn't have to be at a significant price premium. We microscale it, as per CLEAPSS, I reckon the single box we bought two years ago of TLC plates, which I cut into 6cm x 1.5cm strips for use in sample bottles, will last us for probably another 3 years! The kids usually get reasonable results: This was comparing green and coloured autumn leaves.View attachment 4269
The microscope method is rather untidy. It is OK for lower school but not fit for purpose for A level and above as the resolution is poor and there is no documented Rf values in the literature for the mobile phase used. :)
 
OMG, I am definitely having one of those weeks! I carried out TLC of Spinach & some red tree leaves . Worked brilliantly. Similar results to Georges above.
Took it in to teacher where the A level simply filled the mortar & pestles with Spinach etc & just mashed it. Literally the things were FULL of mush. Teacher insisted they had done it properly & it was a 'rubbish' & 'didn't work' so we need to find 'better, fresher' plants. :mad:
When I pointed out that they hadn't done it properly to release pigments she got annoyed & said they did it perfectly. Even with the evidence of mine in front of her! Maybe she thought I had coloured it in with felt tip!!
Some days I just want to throw their practical in the bin & tell them not to bother.
I had same with Maggot respiration yesterday. Worked perfectly in prep room. Class however, are all wandering around, messing about with equipment, screaming & shouting. Then teacher complains that it 'doesn't work'.
It's weeks like this that get me down.:mad::(
It is all a case of Houses for Courses Jay tee. Provided that you use a good size plate and the 9:1petroleum:propanane you can get decent results. You can I know exactly where you are coming from and it does require a bit of skill. I have had Doctorates struggle with it. But when they have seen my time course lapse photography of TLC of plant pigments they have pleaded with me for it to be included in their teaching resources. One less for the book. :D
 
It is all a case of Houses for Courses Jay tee. Provided that you use a good size plate and the 9:1petroleum:propanane you can get decent results. You can I know exactly where you are coming from and it does require a bit of skill. I have had Doctorates struggle with it. But when they have seen my time course lapse photography of TLC of plant pigments they have pleaded with me for it to be included in their teaching resources. One less for the book. :D
What is the method you use for extraction of the chlorophyll and you add sodium or magnesium sulphate to act as a drying agent? How do you preserve the extract for up to two years?

Where can we find the Rf values for your running solvent

I would like to produce a better TLC practical.
 
:)
What is the method you use for extraction of the chlorophyll and you add sodium or magnesium sulphate to act as a drying agent? How do you preserve the extract for up to two years?

Where can we find the Rf values for your running solvent

I would like to produce a better TLC practical.
And so would many others Beaker.:)
Grind with soft sand and propanone then until you get an intense green coloration. decant the liquid and allow to evaporate tp concentrate to concentrate. Remove the water by addind the drying agent. Magnesium sulphate (anhyrous) helps to maintain the integrity of the Chlorophyll.It won't keep for 2 years it will start to degrade after a couple of weeks so you will need to decant it into Eppendorfs, wrap in foil and place in a fridge.

You can work out the Rf values from the pic have provided. Print it out full size then do the maths. The solvent front is clearly marked. remember the middle of a band shoild be measured for each component.

Best wishes and keep safe!:):)
 
:)

And so would many others Beaker.:)
Grind with soft sand and propanone then until you get an intense green coloration. decant the liquid and allow to evaporate tp concentrate to concentrate. Remove the water by addind the drying agent. Magnesium sulphate (anhyrous) helps to maintain the integrity of the Chlorophyll.It won't keep for 2 years it will start to degrade after a couple of weeks so you will need to decant it into Eppendorfs, wrap in foil and place in a fridge.

You can work out the Rf values from the pic have provided. Print it out full size then do the maths. The solvent front is clearly marked. remember the middle of a band shoild be measured for each component.

Best wishes and keep safe!:):)
Thanks do you re-hydrate the chlorophyll with some propanone prior to applying to the TLC plate, with a fine paintbrush?


In another thread you wrote they kept for two years - not that I need it that long -lock down = spend less money, re-evaluate life and what's important - hence think I'm retiring in 2 yrs!!

Stay safe too
 
:)
Thanks do you re-hydrate the chlorophyll with some propanone prior to applying to the TLC plate, with a fine paintbrush?


In another thread you wrote they kept for two years - not that I need it that long -lock down = spend less money, re-evaluate life and what's important - hence think I'm retiring in 2 yrs!!

Stay safe too
No don't rehydrate it will affect their mobility in the solvent. I have kept them for longer in Eppendorfs that were sealed to prevent evaporation of the Propanone - when the Propanone evaporates too much the pigments will come out of solution. Your extract should look like this. Also apply (spotting the sample on the plate) with a capillary tube not a paint brush. Good luck!:)

grass -2 TLC.png:)
 
Thanks do you re-hydrate the chlorophyll with some propanone prior to applying to the TLC plate, with a fine paintbrush?


In another thread you wrote they kept for two years - not that I need it that long -lock down = spend less money, re-evaluate life and what's important - hence think I'm retiring in 2 yrs!!

Stay safe too
Did you spot that the extract shown was from Grass, yes Grass? Eliminates the need to run to the shpp for Spinich which for some particlar reason the Exam Boards specify should be used. Hovever if you look at the quality of the chromatogram I am sure that you will agree good results can be obtained. Two other points to note:

1 The Grass should be young leaves
2 In the extraction process if the chlorophhyll is degraded by loss of magnesium the chlorophyll a and b bands will appear less intense while the Pheophytin a and b bands will appear more intense.
 
Thanks do you re-hydrate the chlorophyll with some propanone prior to applying to the TLC plate, with a fine paintbrush?


In another thread you wrote they kept for two years - not that I need it that long -lock down = spend less money, re-evaluate life and what's important - hence think I'm retiring in 2 yrs!!

Stay safe too
Was that not the thread about amino acid TLC?
 
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