Sugar solution had changed colour - strange... (Nov/12/2009 )

I had prepared 1M D-galactose and 1M D-mannose solutions few months ago. However it seems to turn "orange".
although I haven't plate it yet to determine contamination, but from the solution itself it is clear and no cloudy effect.

My question is:

1) is this normal?
2) can the solution still be use to elute proteins?
3) what is the possible reason for it to turn "orange"

Thank you.

P/s: I'm sorry cos i not a biochemistry background.

i ve heard of glucose and galactose browning at higher temperatures when present with a glycine system... but not sure if this color change is normal... normally sugars wil chnge color only on addition of certain reagents (benedicts the most common)
this may not be any growth but accidental addition of some reagent.. acid.. base... watever... so i wud say its better not to use it for any further experimentation unless confirmed!!!

Agree with PI, never heard of sugar solns turning color by itself!! But upon heating, sugar solutions turn brown

" 2) can the solution still be use to elute proteins? "
Golden rule - Its always better to prepare the reagents afresh in case if you have the slightest doubt about it. That would save you quite a long time in long run

how was the solution stored?

the orange color can be due to caramelization of the sugar (requires heat, maybe sunlight caused it).

if there is an amino acid (eg glycine) in the solution then the sugar may have undergone the maillard reaction.

I store the solution in clear blue cap bottles at open lab benches. Maybe the bottles were being used to prepare agar media before and wasn't well clean. However, both caramelization and mailard reaction requires some heat. From what I understood, both process will not happen in a very slooowww process or motion.

It sounds like somebody in my lab try to sabotage my work...

ya so the best option in any case it re prepare and use!!!
and don keep ur stocks for too long for ur fellaws to fiddle wid it!!!
seems tat u doin fast research... they might just want u to be at the same pace.. sooo...

was the clear blue cap container glass or plastic? was it clean and fresh i.e a new one? First sort out all these problems before you blame your collegues... May be the cleaning agent used for cleaning the conatiner left some residues which caused the colour change..
Anyway for success in regular lab work is to preparae small quantities of solutions and prepared fresh as much as possible..
Dont worry it may not be an act of sabotage or something.. just throw it make frash solutions and start your work..

adrian kohsf on Nov 16 2009, 08:22 AM said:

I store the solution in clear blue cap bottles at open lab benches. Maybe the bottles were being used to prepare agar media before and wasn't well clean. However, both caramelization and mailard reaction requires some heat. From what I understood, both process will not happen in a very slooowww process or motion.

It sounds like somebody in my lab try to sabotage my work...

Thank You Minni,
The cap is plastic, although is not a new one, but we do clean it with standard procedure from detergent washing, autoclaving and oven baking. I had recently tested with our detergent and it doesn't seems to be the case.
Anyway, it doesn't matter anymore because I had prepared new solutions.

Thank you all for your comments and enlightenment.

adrian kohsf on Nov 15 2009, 08:52 PM said: