Australia's Science Forum

Hi
Does anyone know how long you can keep indicator powder for. We have some that has been here for at least 10 years. Does it have a use by date? A recent recipe for making up litmus solution said to use anywhere between 1 to 10 g of indicator per Litre of water,depending on how old it was. How old is too old?
Debbie

no idea buti have stuff here that is 21 years old nad we still use it and still get good results with it. I assume so long as it is kept dry and contaminated free it is all ok

I have heaps of old indicator stock..[eg like 10 bottles of Methyl Red, 8 of phenolphthalein] some are from 'Peking Chemicals'... now try to find the manufacturers/suppliers MSDS for THAT!
Also the MSDS for all those old chemicals from Government Stores..... sigh...

Hmmmmm I KNEW I loved my NEW lab with chemicals all less than 7 years old!!!!!!!!!!

I still have some in lbs. and are still O.K.

I'm with you macca and sunray 18! So many oooold chemicals! I have virtually every indicator powder under the sun - except the one I could have used today! Safranin (gram stain). I will have to buy some
Sue G

Dr Robb very kindly put his chemical expiry date list on our wiki.... www.chemtalk.com.au/wiki

Don't think it covers indicators but VERY useful for most everything else!

Thanks again Robb!

Thanks for your replies. The expiry list by Robb is good.
I guess I'll keep using the old indicators (including the ones from Peking Chemicals) and just replace one or two a year to refresh the stock.
Debbie