Hi, Whilst completing an inventory of our chemicals/substances I came across a couple which did not have expiration dates and some that had actually expired, can anyone tell me what time limit chemicals have and if there is an allowance after the expiry dates? The chemicals in question are:- No Expiration Dates- Methylene Blue Powder, Sodium Carbonate Anhydrous, Potassium Dichromate, Methyl Red, Sodium Diphenlamine Sulphate, Ammonia Solution 0.88. Expired- Methyl Red, Silver Nitrate, Iron II Sulphate Heptahydrate, Phenolphthalien Solution, Sodium Hydroxide. I know that expiration dates and shelf lives are different. I have read that you should never exceed 1 year after the expiry date but on another site it states 5 years and that most liquids have a 12-18 month expiration. Could someone please let me know. Thank you Claire

Thank you for replying Jane, do you know where I could find information on the type of chemicals that would have an indefinite life?

If you are working in a regulated environment to GLP/GMP etc then the simple answer is don't use them as you wont be compliant. To be honest, as an analytical chemist I would not trust any of them for any sort of analysis and would just throw them away, as non of them are particularly expensive, unless you have them by the Kilo or more Re testing them would be a waste of time and money.