I'm struggling to understand Fluorescein Disodium Behavior in temperature. From literature I didn't find a complete overview about its temperature dependence related to pH, maximum temperature stable behavior and light degradation.
Dear Alessia,
your question is a little too vague. At first in what a solvent (water?) and what a pH.
Do you know the Pka/Pkb value of Fluorescein Disodium salt? There are a lot of papers.
Please note that you must have a pure compound for scientific investigations.
What do you mean when you write … maximum temperature stable behavior… ?
Thank you in advance for your Infos.
JRG
thank you, the solvent is ethanol. Even if for some it is not correct to measure pH in ethanol, I always meaure pH 5 when I check my solutions.
Ok, Thank you for the reply. What a kind of ethanol are you using e.g. the % of water in ethanol?
JRG
Please note that ethanol is very hygroscopic. Have you bought ethanol pure quality . What is the % of EtOH?
The same for isopropyl alcohol and Methyl Ethyl Keton. You must use dried and pure solvents in your research.
You cannot measure pH or conductivity because pure and dried ethanol doesn' t ionize. Any pH measures are due to water and impurities. A part of sodium fluoresceinat
will dissolve in EtOH because it is polar and not because it is ionic. Your mixture leads to a very komplexe dissolving behavior.
pH cannot be measured in this mixture .
JRG
Dear JRG,
thank you for all these clarifications. The ethanol we use is 99.8% as ethanol anhydrous. I guess this is what you meant by % of EtOH? I'm sorry but my knowledge of chemistry is very basic. Indeed, about the fact that ethanol might absorb water, I do not have particular precautions except that the tank is open only for refilling inside a room where I have air conditioning keeping the level of humidity constant. What is according to your experience the rate of absorption of humidity of ethanol?
Dear Jean Rene Grezes ,
sorry to bother you, do you know if Fluorescein Disodium might change properties also in solid state? I have a bottle of powder in the lab which has been opened last February. Might the fact of getting in contact with the atmosphere several times, reduce the fluorescent properties of Fluorescein Disodium?
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