recycled CsCl

[c10_dcp2 at RED.WHOI.EDU]

As requested, the following method produces high quality recycled CsCl.
Douglas Prasher, USDA, APHIS
dprasher at aqua.whoi.edu


Recycling of CsCl

1.Store waste CsCl solution in wide-mouth container.  It is okay to include 
waste mineral oil.
2.Pour off as much mineral oil as possible while retaining the CsCl waste 
liquid.  Use a 25ml pipet to remove the remaining oil.
3.Add activated charcoal using approx. 1/2 cup per 2 liters of waste.  Stir at 
least 30min.
4.Filter through TWO layers of Whatman #1 paper into a glass beaker.  The 
filtrate has a yellow color.
5.Boil until supersaturated.  Cool to room temperature and then pour off the 
liquid through Whatman #1.  Save the liquid as the next mother solution (see 
#9).
6.Place the beaker containing the crude CsCl crystals in a 37 C incubator for 
several days to dry the crystals as much as possible.
7.Transfer the solids to crucibles and bake in a muffle furnace at 620 C 
(1200F) for 30min.  Most furnaces can accomodate a limited number of crucibles 
at one time.  Hence, several `bakings' may be necessary.  The baked material 
will turn black.  Allow the crucibles to cool to room temperature.
8.Redissolve the solids in distilled water and filter through a 0.45um filter. 
 The liquid should be colorless.
9.Boil again to supersaturation; allow to cool to room temperature.  Pour off 
any remaining liquid through a Whatman filter.  Add this liquid to the mother 
liquid saved from Step #5.  
10.Dry the crystals at 60 C overnight.  Crush the CsCl crystals using a mortar 
and pestle before using for gradients.