[Histonet] a silly question

[Truscott, Tom]

Hi Nicola, Ask yourself, Would adding 10mg to .4ml be the same as adding
2.5 gm to 100 ml? or would adding 10mg. to 400ml be the same as adding
2.5 gm to 100ml? Good luck< Tom T.

-----Original Message-----
From: histonet-bounces <@t> lists.utsouthwestern.edu
[mailto:histonet-bounces <@t> lists.utsouthwestern.edu] On Behalf Of Nicola J
Broadbent
Sent: Thursday, July 24, 2008 8:37 AM
To: histonet <@t> lists.utsouthwestern.edu
Subject: [Histonet] a silly question

Hi,

 

I'm embarrassed to ask this, but I have a basic question about making
percent solutions (% w/v).  I wish to make a 2.5% solution of drug A in
saline.  I have 10mg of drug A and want to know how much saline to add
to
get a 2.5% solution.  The formula I found for making % solutions is: 

 

%solution  = (dry mass in grams/volume in mls) *100

 

According to this formula, I would need to add 0.4ml to 10mg to get a
2.5%
solution.  I am not sure whether this is correct however, as my
intuition is
to keep the units the same (mg/mls) and here the amount of saline to be
added would be 400ml.  I know this is a bit stupid and I can only claim
that
it is close to Friday and my brain is shutting down...Can someone
resolve
this for me? Help!

 

Nicola J. Broadbent 

 

 

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