HPLC-UV detector destructive?

[Bill]

Hi Group,

I seem to remember from years back that HPLC-UV had the potential to
be a destructive technique, i.e., you could not take the elute and run
it in serial mode to a fraction collector and expect to end up what
you started with. This was with some photoreactive polymers, but was
wondering if anyone had some tips or references on this?

I could split flow to UV and other to fraction collector in parallel
and can think of some experiments to try... run the method, fraction
collect with UV on... run the method with UV off.

It just sticks out in my head the Hospitals, etc. use UV for
sterilization but perhaps thats just for larger molecules that
denature easily, like proteins, peptides, and larger. I'm looking at
small molecules, under 600 m/z which are normal conjugated systems
with a nitrogen here or there.

Any feedback greatly appreciated.

Best Regards

WB

[Marvin]

Post by Bill
Hi Group,
I seem to remember from years back that HPLC-UV had the potential to
be a destructive technique, i.e., you could not take the elute and run
it in serial mode to a fraction collector and expect to end up what
you started with. This was with some photoreactive polymers, but was
wondering if anyone had some tips or references on this?
I could split flow to UV and other to fraction collector in parallel
and can think of some experiments to try... run the method, fraction
collect with UV on... run the method with UV off.
It just sticks out in my head the Hospitals, etc. use UV for
sterilization but perhaps thats just for larger molecules that
denature easily, like proteins, peptides, and larger. I'm looking at
small molecules, under 600 m/z which are normal conjugated systems
with a nitrogen here or there.
Any feedback greatly appreciated.
Best Regards
WB

Most materials are not changed by the absorption of light,
especially at the light intensities in the detector and the
short exposure times. If you are concerned, run a
chromatogram on a portion of a sample or standard, expose
another portion to UV light (e.g., from a pen lamp) and run
another chromatogram with it. Look for large differences.

[M. Farooq]

Post by Marvin

Post by Bill
Hi Group,
I seem to remember from years back that HPLC-UV had the potential to
be a destructive technique, i.e., you could not take the elute and run
it in serial mode to a fraction collector and expect to end up what
you started with. This was with some photoreactive polymers, but was
wondering if anyone had some tips or references on this?
I could split flow to UV and other to fraction collector in parallel
and can think of some experiments to try... run the method, fraction
collect with UV on... run the method with UV off.
It just sticks out in my head the Hospitals, etc. use UV for
sterilization but perhaps thats just for larger molecules that
denature easily, like proteins, peptides, and larger.  I'm looking at
small molecules, under 600 m/z which are normal conjugated systems
with a nitrogen here or there.
Any feedback greatly appreciated.
Best Regards
WB

Most materials are not changed by the absorption of light,
especially at the light intensities in the detector and the
short exposure times.  If you are concerned, run a
chromatogram on a portion of a sample or standard, expose
another portion to UV light (e.g., from a pen lamp) and run
another chromatogram with it.  Look for large differences.- Hide quoted text -
- Show quoted text -

I would add that if it were possible to use longer UV wavelengths (>>
300 nm) if you are concerned. Just check if the absorption spectrum of
your starting sample changes with time or not, if you have a scanning
spectrophotometer and overlap mode available in the program, this
might give a clue.

M. Farooq

[Bill]

Thank you for the kind replied and good suggestions! I guess you need
to push electrons to break any bonds and UV won't do it.

I've had problems with UV in the past with polymers, but it's an
entirely different mechanism. Thanks again!

Bill

[Marvin]

Post by Bill
Thank you for the kind replied and good suggestions! I guess you need
to push electrons to break any bonds and UV won't do it.

Even visible light will do it, if the compound is
photosensitive.

Post by Bill
I've had problems with UV in the past with polymers, but it's an
entirely different mechanism. Thanks again!
Bill