Chromatography of plant pigments

Hi all, We have Edexcel syllabus here for A level. Has anyone else thought the practical seems 'dumbed down' to how we used to do it? Do you all do this version or have you changed it?
Seems very simplistic now, ie: chromatography paper & solvent ( propanone & petroleum spirit)
We used to do TLC plates. What's happened? I find this with so many A level practicals now, not just this one. Some of them are things we used to do at KS3 & 4.
 
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.
 
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::(
 
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::(
Don't get yourself down Jaytee when things don't work it is the Teacher's fault either for not having a clue or not making sure that the students follow the protocol to the letter.:)
 
Don't get yourself down Jaytee when things don't work it is the Teacher's fault either for not having a clue or not making sure that the students follow the protocol to the letter.:)
Thanks. I think it's more that you go the extra mile, try to pre empt what they need & trial & tweek to get things working, then they just moan & simply won't accept that the kids could possibly have b******d it up!
 
It's not you Jaytee When I worked in a sixth form college they did a practical which 'didn't work' so I went in and did the practical as a demo for the students where it worked perfectly as I read and followed the instructions.
 
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::(
Don't worry @Jaytee I have come across the same issues time and time again - the usual reasons are nothing to do with the method, the technician or the equipment, it is nearly always one of the following:
1. The teacher has not got control of the class so the students don't/can't follow simple instructions and/or mess about with inevitable failure.
2. The teacher hasn't prepared the lesson properly so they don't know the procedure themselves and can't guide the students appropriately..
3. They have not allocated enough time to instruct the students prior to the practical relying on the students to work it out for themselves, or haven't given the students enough time to complete the practical.....or both.
4. The teacher just can't be bothered to supervise the practical properly.
5. Of course there is always the teacher who knows better than you and follows their own method that may have worked in the distant past with different equipment or different concentrations.
I'm sure there are other reasons as well ........but definitely not down to a technician like you.
 
Don't worry @Jaytee I have come across the same issues time and time again - the usual reasons are nothing to do with the method, the technician or the equipment, it is nearly always one of the following:
1. The teacher has not got control of the class so the students don't/can't follow simple instructions and/or mess about with inevitable failure.
2. The teacher hasn't prepared the lesson properly so they don't know the procedure themselves and can't guide the students appropriately..
3. They have not allocated enough time to instruct the students prior to the practical relying on the students to work it out for themselves, or haven't given the students enough time to complete the practical.....or both.
4. The teacher just can't be bothered to supervise the practical properly.
5. Of course there is always the teacher who knows better than you and follows their own method that may have worked in the distant past with different equipment or different concentrations.
I'm sure there are other reasons as well ........but definitely not down to a technician like you.
:) Thank you Peter. Definitely 2,3 & 4!
 
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.
We bought a pack 2-3 years ago, wincing at the price (just shy of £50 I think). However, I cut it up into small strips that just fit into sample bottles (about 1cm x 6cm), so I get around 30 runs per sheet and we're barely a tenth of the way through the box, even now. Worth the investment, for the lovely results the kids get.
 
We bought a pack 2-3 years ago, wincing at the price (just shy of £50 I think). However, I cut it up into small strips that just fit into sample bottles (about 1cm x 6cm), so I get around 30 runs per sheet and we're barely a tenth of the way through the box, even now. Worth the investment, for the lovely results the kids get.
it's the chemists who seem to use it all up doing amino acids and aspirin.
 
We bought a pack 2-3 years ago, wincing at the price (just shy of £50 I think). However, I cut it up into small strips that just fit into sample bottles (about 1cm x 6cm), so I get around 30 runs per sheet and we're barely a tenth of the way through the box, even now. Worth the investment, for the lovely results the kids get.
Yes many schools do it that way but unfortunately you just don't get the resolution you get when you use half a plate (as above) or tweak the mobile phase.:)
 
We bought a pack 2-3 years ago, wincing at the price (just shy of £50 I think). However, I cut it up into small strips that just fit into sample bottles (about 1cm x 6cm), so I get around 30 runs per sheet and we're barely a tenth of the way through the box, even now. Worth the investment, for the lovely results the kids get.
What size plate are you referencing? We tend to use either 10x4cm or 20x4cm cut in two, depending on what is the best value at time of purchase. They are used for both plant pigment and seperation of amino acid mixtures, with references. I've had some very good luck purchasing from ebay.
 
What size plate are you referencing? We tend to use either 10x4cm or 20x4cm cut in two, depending on what is the best value at time of purchase. They are used for both plant pigment and seperation of amino acid mixtures, with references. I've had some very good luck purchasing from ebay.
The large sheets I use are 200 mm x 200 mm and I also cut them up to 15 mm x 100 mm and they use those. My problem is how do you all cut the sheets up without bits of silica falling off? I tried a Stanley knife, is mine just rubbish?
 
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