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Hydroquinone as an impurity
Posted: Sat Feb 19, 2005 5:47 pm
by mornell
Hallo together,
I need some help very urgently!!! Who has any experiences about the behavior of small amounts of hadroquinone in GC analyses. (Split/ Splitless, DB5, FID). I have to measure amounts about 0.1 % m/m as an impurity and it is not reproducible at all. What about pH and things like that?
Thank you for any help
mornell
Posted: Tue Feb 22, 2005 2:38 pm
by safwatali
Dear mornell,
What is your sample preparation?, and What is your programing temperature?
Safwat H. Ali
Posted: Wed Feb 23, 2005 12:16 pm
by Victor
Do you mean hydroquinone?
Posted: Wed Feb 23, 2005 8:34 pm
by safwatali
Dear Victor,
Yes, I mean hydroquinone.
Mornel wrote,
"I have to measure amounts about 0.1 % m/m as an impurity and it is not reproducible at all."
So, how did he prepare the sample which contain the hydroquinone?, Also, how did he prepare the sample which contain hydroquinone for injection in GC?
Because all this conditions may be responsible for this result.
Best wishes
Safwat H. Ali
Posted: Fri Feb 25, 2005 11:27 am
by mornell
Dear safwatali,
the sample preparation is a solution in DMF, because the main product has a very bad solubility in most dilution reagents.
The analytical method wants a OV5 GC column with a gradient vom 100 to 300 *C oven temp. It's a split/splitless injector with 250*C.
Best regards
mornell
Posted: Fri Feb 25, 2005 12:59 pm
by Victor
Hydroquinone is rather easily oxidised. It sounds like you are working from a reference where they have managed to perform the analysis by GC??? However, maybe this oxidation is a possible source of your problem. There shouldn't be much oxygen in a GC column.... on the other hand elevated temperature may be detrimental.