SDS solutions behaving, um, oddly.....
rmaldonado at ua.es
Wed Jul 26 06:05:09 EST 2000
sam_ross at my-deja.com wrote:
> Both were prepared from
> the same SDS stock (1% diluted from the 10%), with water from the same
> MilliQ system, stored in bottles of the same type, in fact from the same
> wash-up batch... "Ah", intoned a wise lab mate, "But as soon as you so
> much as touch the bottle of 10%, the whole thing will solidify". Nope,
> it has so far stayed happily dissolved.
We had a similar problem here with 1% and 0.1% solutions, though in
southern Spain there is no problem with the cold. After some
experiments, we conclude that salts remaining in the tubes (some of them
disposable plastic ones) can aggregate SDS molecules. In high
concentration stocks, SDS needs more salt to be aggregated, so it never
happens in the 10% stock.
Try to get more pure water or water form another source and try it.
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