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Dilution problem

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Dilution problem

Postby daphnis » Wed Jan 25, 2012 5:56 am

Hi everyone. I am seeking help on a dilution problem. This is not homework, but for my lab work. I've been working this dilution problem like crazy for the past five hours (believe it or not, I'm stubborn and want to get it done, and I'm stubborn because I want to understand it).

I'm sharing with you what I've done thus far. I've tried two methods. I understand how to to dilutions, trust me, but to get this numbers to work is another story. Help will be much appreciated!

Ligand X
stock: 100 ug/mL
( there's a total of 1 mL of the stock. but we have less than that now. )

[ Method 1 ]
I want to dilute 100 ug/mL to 10 ug/mL. Here is the catch. I need to aliquot 10ug of this ligand into a 6-well plate. Each well will contain 1 mL of media. So when I plate this diluted ligand concentration, the plate must have 10 ug/mL. I am treating 4 wells with this ligand (10 ug/mL in each well).

Here is what I have so far:

C1V1 = C2V2
C1 = 100 ug/mL
V1 = ?
C2 = 10 ug/mL
V2 = 1 mL

When you work out the problem, it will be V1 = 0.1 mL. However, I cannot aliquot 0.1 mL from the stock solution because that'll take too much from stock (that and it's expensive).

[ Method 2 ]
Using this strategy:
I've edited the image to fit my numbers. For the problem worked out below, if I plate 0.01 mL (10 uL) of the diluted stock then I will get 0.1 ug/mL, which is not what I want at all! ... onprob.jpg
( the whole image will not show up in the thread. )

I'm stumped. After working this single problem out for so long, my mind is fried :\
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Postby JackBean » Wed Jan 25, 2012 11:46 am

your method 1 is completely fine, you need 100 ul of your stock per well.

Cis or trans? That's what matters.
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