Solubility of anhydrous CoCl2 under specific conditions might be a factor to consider, but I will leave that aspect to chemistry experts.

However, addition of CoCl2 to a final concentration of 100-400 μM in cultures is pretty standard for stabilization of HIF1 Alpha in hypoxia related studies. It is suggested to prepare a fresh stock solution of CoCl2 and majority of studies cite the preparation of 25-400 mM CoCl2 stock solution for treatment of cultures (PMIDs: 24932611; 21860378; 12242281; 15897903).

For troubleshooting tips & answers to more than 20 similar questions on hypoxia experiments and HIF1A/HIF2A/HIF3A analysis, I would suggest reading FAQs - Hypoxia and HIFs at http://www.novusbio.com/support/hypoxia-and-hif-faqs http://www.novusbio.com/support/hypoxia-and-hif-faqs

Try making your stock in a slightly acid solution (25 mL HCl/L H2O). As Subhash mentioned, try dropping the stock concentration. 1000x is very convenient, so make a 100-400 mM stock. The minute amount of HCl added will in no way impact your cultures.

Hello,

Stock solutions should be kept at RT, 4C or -20C??

Thank you!