About liquid mesurement

[Rush]

hello everybody
I need some advices about liquid measrement(sorry if my english is bad) from somebody who's expert.
the fact is that I diluited too much a chemical, and I want it more concentrated.

a theorichal example:
a chemical we'll call RC
100mg(RC soluble in h2o) in 200ml(H2O)
==> [RC]concentration is 0,5mg in 1ml.

I want to make it 1mg x 1ml or better 2mg x 1ml so I want to reduce the H2O volume by 100ml or more.

My thought was to make water evaporate...but I fear to damage the chamical that is inside, or damaging it...is there some other way other than evaporation?

[dirk]

evaporation does not neccesarily need high temperature.

Things that speed up evaporation without increasing heat:

- large surface area (shallow caserole dish)

- increase air flow (fan / wind)

- low humidity (dry air /dessicant)

You could try this idea: (it is only a thoery for me, I have not tested it yet)

Put a layer of desicant (calcium chloride/"Damp-rid") in the bottom of a large container with an airtight lid.

Put casserole dish (with solution to be evaporated) in the plasic container.

Put small fan (computer fan?) in the container to provide airflow be carefull to avoid blowing desicant into the solution.

The water from the solution will evaporate quickly because of the dry air flow. this water is then absorbed by the desicant ensuring that the air remains as dry as possible.

This is better than just fanning the solution because you do not get dust or cat hairs in the solution.


You could also try freezing the solution very slowly, (break up the ice as soon as it forms and stir regularly), hopefully the ice will be pure water and can be removed when half of the solution is frozen


what do you guys think of these suggestions - any comments?

[robertone]

The best sollution depends completly on the nature of the RC. If the RC is a salt (e.g. won't evaporate) vaporising the water under reduced pressure or (most simplist) use an desiccator with an desiccant like calcium chloride or calcium oxide.

[Rush]

thank you for your advices.
yes, the substance is an hydrochloride salt.
can you please make an easy example for the two methods you said?
1.vaporising the water under reduced pressure(you mean boil the water?how to reduce the pressure?)
thx