Hi Logan,

I would recommend using a nitrile-rubber stopper or septum, this should make a tight enough seal. It is also advised to store the Osmium solution in the dark and preferably at 4 degrees C. Keep in mind that the solution has a limited shelf-life,

if it changed colour from yellowish to grey most of the osmium will have reacted. (I usually make 5ml 2% Osmium in a glass tube as a stock solution.

For the best contrasting i'd reccomend using a fresh (still yellow) solution in a suitable buffer ( maleate buffer, sodim cacodylate buffer or anything else that doesn't react with the Osmium) .

For safe handling, use Nitrile-rubber gloves, latex will not be sufficient. Work in a fume hood, and replace your gloves if you notice dark spots on them. You can neutralize the osmium waste by letting it react with ascorbic acid or unsaturated lipid (vegetable oil).

Best,

Rob

Hi Logan,

I would recommend using a nitrile-rubber stopper or septum, this should make a tight enough seal. It is also advised to store the Osmium solution in the dark and preferably at 4 degrees C. Keep in mind that the solution has a limited shelf-life,

if it changed colour from yellowish to grey most of the osmium will have reacted. (I usually make 5ml 2% Osmium in a glass tube as a stock solution.

For the best contrasting i'd reccomend using a fresh (still yellow) solution in a suitable buffer ( maleate buffer, sodim cacodylate buffer or anything else that doesn't react with the Osmium) .

For safe handling, use Nitrile-rubber gloves, latex will not be sufficient. Work in a fume hood, and replace your gloves if you notice dark spots on them. You can neutralize the osmium waste by letting it react with ascorbic acid or unsaturated lipid (vegetable oil).

Best,

Rob

Bottle should be of dark glass and wrapped in foil (too keep light away). Several layers of tightly wrapped parafilm (around cap and bottle neck) should catch most of the Os vapor. I do not know if reliable stopper for Os exists.

This is the tube + stopper I use, the seal is pretty tight, you can see that the discoloration due to the osmium vapour doesn't extend to the top of the stopper. With this tube ( wrapped in tin foil and stored at 4°C) I've stored a 2% osmium solution for about 2 weeks without the solution turning grey.

You will have to change the stopper after a while because the rubber will harden due to the osmium (so the seal will be less tight).

Since the evaporation of Os-fumes due to the vapo(u)r pressure is higher at RT than seen at lower temperatures (I talk about either fridge at +4°C, or freezing at -24°C at least) I'd recommend to store the OsO4 solution not at RT.

The matter is a bit complicated to discuss in a few words or sentences...

but I've made my own / personal bench-work-experiences in the Lab during 34 years of performing (T)EM on clin.-diagnostic human specimens and therefore (since the throughput of specimens was rather high) developed an optimized preparation protocol (derived from several sources, but most of that my own cost effective / ecological technique from MILLONIG's Laboratory Handbook of Biological Electron Microscopy, 1976.)

If you are interested in that technique /protocol - please - you let me know. I have to admit that several "fault-finders" in the mid 80ies deemed my practical as well as well-considered approach expendable...So I do not want to make a fool of myself in this forum.

Best regards W.H.M.

PS: OsO4-vapours evaporate and blacken most plastic or rubber and nitrile made stoppers. Much more at RT than at low temperatures. This has been seen many times in queries and requests for help during the 80ies and 90ies (e.g. MSA-Listserver Archives....). These vapors over effectual / sufficient time blacken especially the interior of fridges (even if at +/- 0° to +4°C).

As Vladimir points out, two to three layers of parafilm around the/a cap and the "bottle's neck" may help for a certain period of time to prevent.

Dear Logan Collins : We do not know about the situation with and what your safety officer is thinking about (if there is such a person or admin.)

Even frozen OsO4 solution (best storage always stock solution in bi- or tridistilled H2O) emits vapors over a long storage period in the freezer @ -24°C.

So the best storage of a stock solution of 2% hydrous OsO4 IMHO is/was:

Amber Acid-bottle(s) with ground cap + parafilm 1-2-3 layers...

just to show you as examples (DISCLAIMER: no affiliation or financial interst with any of the mentioned companies, suppliers...):

https://www.google.com/search?client=firefox-b-d&q=S%C3%A4urekappenflasche; or

http://www.unilab-technologies.at/119/1/KD0/category/90050106/S%C3%A4urekappenflaschen.html?sid=c5s9sr563nc6psa88e0rv8dut1, or

https://www.fishersci.co.uk/shop/products/amber-glass-ground-caps-acid-bottles-3/p-8011297 and (for sure) many more suppliers.

STORAGE always in the dark, for use approx. 1-2 hrs prior to use let warm up to RT (some caution during handling and pipetting then for preparing the working solution +/- freshly) naturally is advisable.

Best wishes and good luck, WHM.

My lab refrigerator did not have visible Os contamination after 15 years of storing 2% OsO4 solution. I have stored it up to 6 months at times (replaced it when it was finished, not because it went bad). Parafilm and additional plastic box for placing a bottle with Os. But säurekappenflasche, suggested by Wolfgang H. Muss , looks even better.

Dear all, thank you for appreciation. I forgot to tell that during my studies in the late 1970ies I saw some refrigerators with black(ened) interior...but that was due to totally different behaviour of "researchers" regarding GLP as it fortunately happens to happen today. The refrigerators in our (my) lab designated to contain solely particular / specific chemicals and solutions (mainly fixatives and/or other working solutions) were Os-black free (:-)) until I had to leave...(; -|)

Dear Wolfgang, indeed, I saw a few "black" refrigirators too, but the problem there was not in physical properties of OsO4 :)

Dear Denis Korneev ... may I guess: long standing mellow Scotch fillet....."Black label" (:-))

(Apologies if I was impolite [ 'geopolitically incorrect ' or - regarding Australian cuisine - impolite....] with this or under the circumstances did insult anybody

Dear Wolfgang H. Muss , good idea! I will try it :)

No, I meant just contaminated lab fridges. But to do that, OsO4 should be mixed with a dozen times more dangerous reagent - idiots...

Dear Rob Mesman - honestly commenting on (cf. your answer [001] :

"You can neutralize the osmium waste by letting it react with ascorbic acid or unsaturated lipid (vegetable oil)."

[NB:

for "personal, political as well as reasons of national / international affairs' " correctness the following opinion must NOT be taken to be 'anti-personnel' / or directed against you or other (living) persons!]

Hopefully you are aware of another "safe" OsO4 deactivation procedure....safe, reliable and more ecological and keeping precious and rare element ready for recycling (if such once is demanded) and you don't need to use vegetable oil and (as of some indication from suppliers' catalogues....) "spill with plenty of water into /down the sink....

J. A. KIERNAN, ikon in 'biological chemistry' /Histology, Histochemistry & Staining affairs, already in the 1970ies ff [cf. KIERNAN J.A.: J Microsc 113:77-82

(1978)] and not the last time in 2000 via Histonet-Listserver (cf..: http://www.histosearch.com/histonet/Nov00A/Re.quotDisposalquotofOsmi.html ) in RE to Stephen Asquith #) see bottom

stated (in extracts):

(Quote): "Os is a rare element, so disposal of used solutions should consist of

recycling, not dumping, even though osmium compounds are

not considered environmentally hazardous ...." and "....If OsO4 slops are collected in alcohol [NB: use of once or twice used and collected '100% Ethanols from last steps of dehydration in EM-processing), the osmium (now in the form of crude, harmless, insoluble osmium dioxide) can be reoxidized, purified, re-reduced to pure OsO2 and stored. OsO2 is easily re-oxidized to give a buffered solution of osmium tetroxide (2% or less) ..." AND:

"... Osmium tetroxide collected into vegetable oil could not be recycled by the simple method cited above, and the recovery methods used by chemists (which use apparatus etc not found in histology labs) would be made more difficult by the presence of the oil." (End of quotes).

I have to admit that from starting my work as EM-ist in Feb. 1981 I practiced 'deactivation' (= reduction of used OsO4 hydrous or NaPO4-NaPO4-buffered solutions), collection of the precipitate and storing for further processing / recycling under conditions as described in the KIERNAN J.A. (1978)article:

"Recovery of osmium tetroxide from used fixative solutions", J Microsc 113: (Pt 1, May 1978) 77-82.

Today - I was told some years ago - such cumbersome activities aren't contemplable or taken into account any more - because "OsO4 crystals are cheap and spendable..."

Thanks to the suppliers.

And - yes- finally I know that nobody will have time left to occupy oneself with and reading about facts about the chemicals that are needed AND used then in preparative work and such economic and - most obviously "ecological" questions any more... (we delegate to our / the beloved and popular 'saftey ' ##) see bottom officers' and their provisions.

Also I know that the 'energy crisis' and hence 'climate change crisis' does not exist.....

this MUST be true because (not only!) in my country electrical energy is delivered from the socket...(;-||)

Best WHM.

Added by edit 23 mins after initial posting for:

#) cf:

http://www.histosearch.com/histonet/Nov00A/DisposalofOsmiumTetroxide.html

'Disposal of Osmium Tetroxide Waste', continued with Re by Dana Dittus: cf.

http://www.histosearch.com/histonet/Nov00A/Re.DisposalofOsmiumTetrox.html

and followed by Re (by the famous Gayle Callis, Univ. Montana @Bozeman):

http://www.histosearch.com/histonet/Nov00A/Heavymetaldisposal.html

Heavy Metal Disposal

and ##) uupps...this naturally was meant to be written as "safety"...officer ;-

Hi @Wolfgang H. Muss

I indeed should have mentioned that all osmium waste should be disposed of appropriately

(Which in the Netherlands would be Class 6, heavy metals in solution).

Personally I do not neutralize the osmium waste since I have the waste container in the same fume hood as I do the staining.

I'm not sure if in the reaction with ascorbate the osmium is irreversibly bound (and therefore not recyclable) I would have to look that one up.

Best,

Rob

Dear Rob, thank you for your statement.

I remember attempts in the late 80ies to convince some national Societies for EM to motivate EM-Lab-leaders / head staff to collect OsO4 waste and then to commission a (specialized) company to recycle OsO2 as a batch for reuse. I had ordered a qualitative analysis at

Johnson Matthey & Brandenberger AG Switzerland then....

the test results regarding the "purity" and quality to be used as own source of using OsO2 were really promising...

but then... nobody but ONE EM-unit-leader in Switzerland (and he retired soon after I contact him with regard to start cooperation) remained in the campaign [Austria, Switzerland, Germany).

Today, as of my knowledge, there might be small companies in Germany dealing with used heavy metals, especially rare and precious metals, including Os(O2)...

( I may have e-mail addresses in my PAB-files 2015 -2016).

Best regards, Wolfgang

Hello, Logan

Many good suggestions were given here. I just want to add, that in addition to low temperature (about +4), we stored osmium tetroxide in a glass tube or small bottles (in the photo) with rough ground-in glass plugs. In my opinion, in the presence of many users of the certain refrigerator and high degree of its filling, it is more safely to use bottles as they are less inclined to knocking out. With a parafilm wrapped around an upper part of the tube/bottle it seems to work well enough. I also wouldn't recommend to store solution for long, and to monitor the solution visually. As for plugs, we also tried nitrile-rubber plugs, and used it sometimes too.

Find the file attached for Osmium tetra-oxide handling.