EtBr Safety / CsCl disposal / recycling
ED at micro.uct.ac.za
Mon Jun 21 05:13:44 EST 1993
> To: methods-and-reagents at net.bio.net
> From: metzler at sara.cc.utu.fi
>....... and dump the decontaminated buffer
> or CsCl solution down the sink.
> ...whether it is OK to dump CsCl down the drain.....
YOU DUMP CsCl DOWN THE DRAIN???!! WHAT SORT OF ECO-CRIMINAL ARE YOU!!!
Seriously, though, CsCl is not exactly environmentally beneficient- and is
EXPENSIVE, at least in this part of the world.
So we RECYCLE it - and it is not particularly difficult, can be done in
bulk, and provides material of sufficient purity for run-of-the-mill
plasmid purifications. It also postpones the problem of disposal a
Here from our Departmental Handbook:
CLEANING-UP CAESIUM CHLORIDE FOR RE-USE;
Author: Eric O'Neill, Dept. Microbiology, Univ. Cape Town
The success of this method is dependent on your collecting all
the CsCl used for density gradient purification of plasmids/
whatever: to make it worthwhile you need a minimum of +1 litre
waste, collected in sealed bottles.
1. Stir in Merck decolorising charcoal powder (about 3g/litre)
into CsCl waste: this step removes DNA, RNA and ethidium
2. Pass through Whatman's No. 4 filter paper.
3. Boil down until CsCl starts to crystallise (USE BOILING
BEADS!! - IT WILL BEGIN TO BUMP AT THIS STAGE)
4. Cool down to room temperature for full re-crystallisation.
5. Pour off mother liquor (this is brownish due to
caramelisation of Tris/whatever).
6. Redissolve in de-ionised water, repeat re-crstallisation
7. Dry crystals: under vacuum if possible.
THIS IS NOW READY FOR USE AS PLASMID-GRADE CsCl: crystals may
need grinding to reduce their size for easier handling
8. Return mother liquor to next batch of waste CsCl.
| Ed Rybicki, PhD | "Lord, won't you buy me |
| (ed at micro.uct.ac.za) | |
| Dept Microbiology | A Mer-ce-des Benz..." |
| University of Cape Town | |
| Private Bag, Rondebosch | |
| 7700, South Africa | - Janis Joplin |
| fax: 27-21-650 4023 | |
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