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Morgan
International Hazard
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Registered: 28-12-2010
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Quote: Originally posted by Rainwater  | Back in February I placed some MgSO4 and freshly distilled 96% ethanol into test tubes to dry.
I dont need much each a time so I usually make a bunch of tubes (20ml), use what i need and discard the rest.
Monday, my last 2 tubes where crystal clear, today they are tented yellow.
MgSO4 was obtained at the pharmacy as a oral laxative, dried in a vacuum at 400c for 2 hours, it should be pure. |
I've had rubber stoppers "degrade" over time so maybe silicone rubber stoppers would be something to try I don't know.
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Morgan
International Hazard
Posts: 1663
Registered: 28-12-2010
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| Quote: Originally posted by Morgan | | Quote: Originally posted by Rainwater | Back in February I placed some MgSO4 and freshly distilled 96% ethanol into test tubes to dry.
I dont need much each a time so I usually make a bunch of tubes (20ml), use what i need and discard the rest.
Monday, my last 2 tubes where crystal clear, today they are tented yellow.
MgSO4 was obtained at the pharmacy as a oral laxative, dried in a vacuum at 400c for 2 hours, it should be pure. |
I've had rubber stoppers "degrade" over time so maybe silicone rubber stoppers would be something to try I don't know. |
One time I went to use a large collection of black rubber stoppers after a few years of storage and the plasticizer had leached out and made them
greasy.
Rubber stopper tidbits (yawn)
UPDATE [1/12/2018] Becton-Dickinson (BD) informed FDA that it is no longer using the rubber stopper material associated with loss of drug potency in
its general use syringes, and BD has instead returned to a rubber stopper it used
previously in the syringes.
https://www.fda.gov/drugs/drug-safety-and-availability/fda-n...
Toxic effects of lab-grade butyl rubber stoppers on aerobic methane oxidation
https://aslopubs.onlinelibrary.wiley.com/doi/10.1002/lom3.10...
Stop that. It’s degrading!
https://cen.acs.org/materials/polymers/Stops-degrading/97/i5
Chemical Leaching of Rubber Stoppers into Parenteral Solutions
https://journal.pda.org/content/37/3/89
On prolonged storage, a formulation that contained atropine produced lethality in mice. The toxic material originated from zinc compounds that were
present in the rubber stopper and plunger of the container and that subsequently leached into the formulation.
https://pubmed.ncbi.nlm.nih.gov/4032257/
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