Stock and working solutions

[linotas]

How long do you keep your working solutions for? Do you just wait till something is depleted or do you do a regular stocktake and get rid of anything over X years old?

I have been transfering working solutions to our new lab and, apart from dumping the dregs of stuff and bottles with things visably growing , There is some stuff that is years old that I am wondering if it is worth keeping.

[dime]

Well I'm of the school, if it isn't broke don't fix it. Like you, I discard ones with stuff growing or lurking in the bottles. But unless they specifically ask for freshly made solutions, I use what I've got. I think some solutions, like iron ones don't keep, but other more qualified people can no doubt tell you which ones. I might add, I haven't had any complaints in nearly 19 years. cheers

[RosalieM]

Same. When a bottle is getting low, I make up more. The bottles I use hold just over 2L so usually when they are nearly empty I make up 2L. Mostly our 'stock solutions' are used to fill up the dropper bottles, which are then used by the kids, so it takes a while to get through 2L. 0.1M NaOH I have in a 5L bottle as it is usually used in large quantites. The ones that need to be made fresh I just try to make small amounts and dispose of what's left over.

[lurra]

Me too why reinvent to wheel

[fibreweb]

I use what I have and make new solutions up as they are needed.

My stock solutions are only in 250 and 500ml amber bottles so the most used ones are made up at least once each year.
Sometimes I have utilised the senior Chemisry classes to make up new solutions when they are doing the unit in yr11 on making up solutions of a known molarity. Rather then they all make up 8 lots of 250 ml of something only to discard it.

I just went to check how long ago I made up some and realised I have been very slack and havent updated the "Date Prepared" on their labels so it looks like they are all about 6-8 years old! I must update the labels sometime.

Wendy

[linotas]

Thanks everyone.

We just have so many duplicates (and triplicates, and quadruplicates!!!) of things. I just do not see why we need so much! I have been very ruthless this afternoon, hope my job share ( Hi if you're reading ) doesn't take a fit

[smiley]

I'm with the others. Considering we're not running analytical laboratories here, I'm not too fussed about old stock. I do make new stuff for the Seniors, when they're doing titrations etc.