USE BY DATES

[Linda26]

Hi Everyone

Just wondering, how do I find out use by dates for chemicals that have been made up.
Am not sure how long we can keep them. We have some that go back to the 90's

[Labbie]

We have some from the 70"s NO joke. Unless they are a mass (All stuck together) I still use them. Our Budget just does not permet us to keep purchaseing fresh chemicals. I have not had a problems so far. Only one chemicals had little black bits in it. So out it went. I do not know any thing about USE BY DATES for chemcials. Perhaps this is a new thing???????

Sorry re-reading your request I see you mean Soultions. Unless they have gone a funny colour, or segiments are sitting on the bottom of the bottles. I bet they still work just fine. As you make up new ones just start putting a date on. We are surpose to put a date on the soultions as we make them up anyway.

[Linda26]

Thank you that is a big help, as I wasn't sure if I should keep them or throw them out.
We can't afford to replace them either.

[bindi]

Im with Sue,
I keep everything till it no longer works, goes hard or changes only then I buy or make a fresh batch.
Some things we use only in very small amounts and dates back to the 80s which includes our agar!! the previous tech must have got a good buy and we had kilos of the stuff , I have never bought any and I have been here 6 years and its still good

[bindi]

Im with Sue
I have chemicals that go back to the 80s. If it still works, hasnt gone hard or changed I use it. The last Tech bought kilos of agar which Im still using and I have been here for 6 years and it still works

[rosiegbh]

Hi,
I don't have anything in writing but going back to Glen Sawle(Chief education officer, Science) at his workshop earlier in the year, he said that solutions should only be kept for 2 years from date of preparation. Of course as Sue said if sediment and colour change then toss out earlier. I did have some old solutions prob 5 years from the time they were made up and they seemed ok. The teachers didn't complain when they used them but it is good to have a preparation date on made up solutions so at least you know how old they are.
Rosemary

[bindi]

Sorry for all my POSTS
I kept getting 'error on server' message and no 'message was successfully posted' so I kept trying

[Labbie]

I have deleted the extra one for you.

[coxy]

We have a teacher who has a Dble Major in Chemistry and she told me that chemicals do not go "off". However, if something is congealed and gluggy I get rid of it, otherwise I only keep stuff no older than 6 years (and only if I use it at least a couple of times each year).

[Ocker]

Hey Bindi, you're in for a shock when you go to buy agar

[Robb]

Hi All,

Just reading the previous posts and I am amazed to read what I am actually seeing. Hmmmmm....... without being rude I can't believe how people can take things into their own hands without first double checking, even in literature. Of course Chemicals DO have expiry dates. Just look at examples of Sodium Dithionite, Sodium/Potassium Dichromates, Hydrogen Peroxide, Sodium Hydroxide, Chloroform.. Just to name a few...... (I know a couple of these chemicals are banned but please don't comment on these as the indicated chems are set as examples), the decomposition of each of these chemicals I will list.

Sodium Dithionite - Decomposes in Sulfur Dioxide and Fire (That's right FIRE!) if exposed to the Air and Moisture for prolonged periods.

Sodium/Potassium Dichromates - These decompose into the Sodium/Potassium Chromates (poisonous compounds with release of CrO also very poisonous and very unstable).

Hydrogen Peroxide - This loses its strength and maybe you have not directly seen this but it does decompose into Water.

Sodium Hydroxide - Interesting Prolonged exposure to air will cause the compound to gain moisture and clump together, this causes heat and can melt of break the container it is housed in (release of excessive heat is most common).

Chloroform - Well, well, well.... It is stored in (OR SHOULD BE STORED IN brown glass) this is to minimise the amount of light that is absorbed by the organic liquid. Upon long periods of storage with even small amounts of light the Chloroform in gaseous form decomposes into the cancer causing Phosgene. I have done previous studies of this phenomena and I have found it to exist in small quantities even in new reagent straight from the supplier..

What I have to suggest to everyone, is that we be careful with the advise we give as the repercussions can be disastrous, any misleading information can render prosecution or lengthy court proceedings due to false information given for particular information, I am one to at least double check my information against sources that have proven information that I can use in the event of any mishap, and in my profession you see a lot of this even from the first second and third year Uni students upcoming..

All of us here on Chemtalk are offering great advise and we need to keep this up, but there some things that just sneak through that are right but there is just a little more to it..

I trust you all agree.....

Cheers,

Robb.....

[noona]

HI Robb
Thanks for the info hope it helps others as well
Noonna