Hello,

No it is not. For this purpose you shouldn't use formalin and room temperature.

You should keep the samples frozen. Also, I don't know if fecal samples needs further processing and preservation other than freezing or not. The sample may contains materials affect cortisol assay or stability. You should not that, also.

Dear Seyyed

thanks a lot for your feedback. I was afraid that formalin is not good.

cheers

David

Do you mean cortisol or corticosterone? I guess cortisol is the primary glucocorticoid in humans but i'm not sure regarding other primates. Corticosterone which is the primary glucocorticoid in rodents is routinely analysed in samples that have been stored in ethanol at RT. I would suggest you analyse some and see what the levels look like, maybe its not so bad.

Hello John

thank you for your answer.

Yes, it is cortisol. I'll try to use ethanol and to do some analyses to see if it works.

Cheers

David

Hello David,

I know someone who will know the answer, he is a colleague of mine at vetmeduni vienna. His email is [email protected]. Maybe worth sending him an email

Hello Teresa

thank you for the contact. Yes, I'll email him.

Hi David - if it was stored in EtOH or another OH for long periods of time at RT or frozen, you have already started the extraction process. As long as that time of 'extraction' is the same, none of the fluid is lost, and the subsequent extraction method is the same, you might be OK. (though, in other words, I do not think that samples stored in EtOH at RT are an ideal way to store fecal samples for subsequent extraction of hormone metabolites).

For formalin, I am not sure because it isn't clear to me if the metabolites will start to be extracted from the feces. There is also the issue of microbial activity in the feces, which is a problem if at RT but perhaps not if the samples stored in formalin are thoroughly mixed up in formalin. Coming to think of it, we have meerkat feces that were split in half and stored either as a) immediately frozen or b) stored in formalin at RT (for parasite work). It could be possible to assay fecal Cort metabolites to assess differences.

If freezing is impossible in the field, there are other methods to preserve the metabolites without a freezer rather than storing in EtOH or formalin at RT. See Jacinta Beehner's work in geladas and other primate species. She directly extracts the metabolites in the field and stores them on cartridges at RT and found that to be as good as directly freezing.

Hi Ben

the Beehner's work sounds cool, I'll look at it.

if freezing is possible, having aliquots stored in different ways would be

a good way to test this. I'll try.

cheers

David

Rupert Palme is definitely the guy you should be emailing. He has done extensive stress work and is more than willing to share knowledge. He saved me several more months of battling with extraction processes with a single sentence. Good luck!