OCR BIO PAG 6.1 - Identification of the amino acids in a protein using paper chromatography

Anyone had success PAG 6.1? We manage to get amazing results with the plant pigment chromatography but amino acids in a protein using paper chromatography seems to be useless. My team in the past have used the suggested digested egg white to limited success and we currently send out a solution with mixed amino acids, again with limited success.

Where are we going wrong?

We use paper chromatography paper and gas jars, probably 20cm long, so should have a long enough length to get enough variation in travel for grabbing the rf values, but nope, the biology gods seems to hate us on this one.

Would love any suggestions :D`
 
CLEAPSS has a practical sheet for amino acid chromatography (PP062), but it is for pure amino acid solutions not from a protein. There may be some helpful tips on it though.
 
We trialled and trialled this one, spent a ridiculous amount of time and just couldn't get it to work. We now just do grass chromatography with TLC plates and get reliable results every time.
 
CLEAPSS has a practical sheet for amino acid chromatography (PP062), but it is for pure amino acid solutions not from a protein. There may be some helpful tips on it though.
Yea, we've spent ages trying to get it to work via the CLEAPSS method too, just can't get anywhere.
We trialled and trialled this one, spent a ridiculous amount of time and just couldn't get it to work. We now just do grass chromatography with TLC plates and get reliable results every time.
I have this one down to a tee, used for the L3 BTEC and had massive success, ended up using spinach leaves, did a mash up of the CLEAPSS and another method, the A level biologists have told us that it falls in the wrong year for them so insist on amino acids...

You'd think they'd want one that works and do it in second year inste\ad of insisting on doing it in 1st year and having to bodge results :magician:
 
Would be AQA A level chemistry here with amino acids from the chem store.

Have a look in the aqa prac guide.
 
Our BTEC students do the Amino acid chromatography experiment as per the CLEAPSS advice, it works well but the results soon fade after development with ninhydrin so I always recommend taking a picture with a ruler along side the filter paper. Using Soy sauce works okay but isn't as clear, the main problem is the time it takes the experiment to run.
 
Student carried out this pract on Mon. Do you think it would be fine to develop using ninhydrin on Fri which is when they have their next lesson. I really don't have the time to do this for them as on my own this week and last
 
Provided they dried quickly originally and haven't been exposed to moisture, i can't think why it would not work.

By the way I have just found out that if you spray the stained chromatogram with 1% cupric nitrate in acidified ethanol it fixes the chromatogram permanently. The stain does go from purple to red though.
 
Last edited:
Our amino acid chromatograms were always pants until I started spraying the chromatograms with ninhydrin whilst they are flat, previously they had been sprayed whilst hung to dry on a makeshift washing line and I think the ninhydrin must have made the split amino acids drip off the paper.
Since I have been doing this they work great. We use a mixed sample of 1% amino acids Lysine, alanine, valine and leucine.
 
^ I also tried it using the solid amino acids from Timstar, then diluting to a 1% solution with distilled water and propan-2-ol (9:1). It worked a treat! I altered the CLEAPSS method a little, having the first class using mounting needles instead of cocktail sticks. The second dipped a cotton bud into the solution and gently dotted the paper with that. Both worked well, but the students found the latter much easier.
 
Top