Finding Final concentration after dilutions

[FireWarden]

Hi. Ive been trying to figure this out but havent been able to get a concrete way of doing this.

I have a stock solution of 50pg/ml. The stock solution is diluted a number of times:

Dilution of stock
0.0001
0.001
0.01
0.1
0.1
0.5
0.5
1

Volume of Diluted stock taken
7.5[µL]
7.5
7.5
7.5
75
75
175
175

*the two lists should be beside each other and the rows should match...each row would basically be a well and a point on a graph*

Then a volume of this stock (noted above) is taken in microlitres, added to an ELISA reaction which has a total volume of 200 [µL]. The aim of this question is to make a standard curve blah blah...i dont need help with that. I need help in calc the final concentration for the stock after the Stock has been diluted and taken with the volume indicated.

I know I have to use C1 x V1= C2 x V2......C1 is the diluted concentration and V1 is the volume of diluted stock take...right?

C2 is what I need and V2 is the 200 [µL]...correct?

So its simple algebra. Where I am getting confused is whether or not I should convert the stock 50picograms/ml to 50 picograms/ [µL]....so that all the units are the same...or does that matter?

Can i just go.....50pg/ml x 0.0001= C1
and 7.5 [µL] =V1

and go on from there for each one to make my points on the curve? Any help with be great.

[JackBean]

how can you get different dilution, when using the same volume?

[FireWarden]

I am not sure I understand your question...try to think of each row as a well...

so for the first well...

1.Dilution of the 50 pg/ml stock is 0.0001 and the volume of stock is 7.5 mirolitres
2. dilution of the 50 pg/ml stock is 0.001 and the volume of stock is again 7.5 microlitres

...this is done for each row. I am looking for the C2 for each of those rows.

[JackBean]

OK, forget now about some dilutions.

Your original concentration is 50pg/ml in this volume:
Volume of Diluted stock taken
7.5[µL]
7.5
7.5
7.5
75
75
175
175

into final volume of 200 ul, right?
Than you have to get the same contcentration in first four wells