Old indicator stock

[debbec]

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

[dolphinscales]

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

[sunray18]

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...

[vlclabbie]

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

[macca]

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

[SGG]

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

[vlclabbie]

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!

[debbec]

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