HPLC samples degraded

[riya]

Hello everyone....Please help me with this problem.

I had prepared my samples for HPLC analysis but due to certain problems they could not be run on HPLC and after 2 months I am able to analyze them. But on analysis of chromatogram I am getting other peaks alongwith the peaks which I desired.

I had performed extraction with diethyl ether and dried the samples overnight and then next day kept them closed in vials at room temperature and not at 4 degree celsius and not in dark for 2 months. My samples were of epoxide and diols.

Can anyone tell me whether my samples got degraded over the time even in dry form?

Should HPLC samples always be run fresh and not after long time .

[Gerhard Kratz]

Plan your work carefully. Prepare new samples!
Today you buy a fresh bread and tomorrow it is from yesterday!

[Consumer Products Guy]

Should HPLC samples always be run fresh and not after long time .

In general, all samples should be prepared fresh unless you have verified and documented that they are stable. We generally run samples the day of preparation.

Go ahead, ask the USP people what "make fresh daily" means, whether "daily" means 24 hours or if the stuff goes ^&*##^*#@ at the stroke of midnight, like Cinderella ! I assure you that they will get mad and not answer, but it's a legitimate question. Let's just say is that I did not get a real answer when I asked them.

USP did also not answer my question about Volumetric Solutions like sodium hydroxide when I asked "what does 'standardize frequently' really mean?" Every five minutes, five hours, five weeks....

[riya]

Thankyou for your suggestions


I will prepare fresh samples and then do the experimental work.

[Consumer Products Guy]

Thankyou for your suggestions


I will prepare fresh samples and then do the experimental work.

It might be of interest to run the freshly-prepared and the older samples together in the same sequence. But what do I know - the USP thinks I'm an idiot !

[tjbr]

Hi,

Best practice would be to run your samples as soon as is practical after preparing them. The exceptions to doing this would be:

1) Stability is proven.
2) There are no replacement samples.
3) It is early qualitative development work.
4) A customer has requested it and will justify/take the risk.

Hope this helps.