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# 100 micro molar to 250 micro molar

17 replies to this topic

### #16 rhombus

rhombus

Rhombus/Uncle Rhombus

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Posted 01 October 2012 - 04:31 AM

You have an antibody solution that has a concentration of 600 ug/ul. You want to make th following dilutions.

10 ul of 600 ug/ul Ab +190 ul of buffer to make a 1:20 dilution at ________ ug/ul.

This is how I did it.

1. 600 ug/ul times 10 ul= 6000 ug

2. 6000 ug/200ul= 30ug/ul

I know that this answer is correct because I checked. I don't understand how this gives you a 1:20 dilution. Why is the 1:20 given? I did not use it in my calculations. It seems that I am missing some concept. Can someone clarify this. I would have thought that you would divide 30 ug/ul by 20.

Uzalive

Dear Uzalive,

Dilution factors are always what students and some researchers have problems with. Large volumes are sometimes easier to deal with than smaller ones. The problem with research is that the antibody, drugs and compounds we use are expensive and therefore we cannot make up litres just to keep the maths easy. With dilution factors:-

1:10 is 1ml to 9mls of diluent (total 10mls of solution)
1:10 is 0.1ml (100ul) to 0.9ml (900ul) total = 1ml
1:10 is 0.01ml (10ul) to 0.09ml (90ul) total = 0.1ml

With your antibody at a concentration of 600ug/ul, a 1:20 dilution is:-
1ml to 19ml
0.1 to 1.9mlml
0.01 (10ul) to 0.19ml (190ul)
Giving you a final concentration of diluted antibody of 30ug/ul

You have to practise and be able to convert/look at different ways of stating the same volume, measurement etc

Hope this is useful

Kindest regards

Neale

### #17 calculation

calculation

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Posted 12 October 2012 - 01:50 PM

I have 100 micro molar dNTP stock, how do i convert it to 250 micro molar as i need 250 micro molar for my PCR?

### #18 bob1

bob1

Thelymitra pulchella

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Posted 12 October 2012 - 07:16 PM

You can't go from less concentrated to more...

however, you probably want 25 uM rather than 250... so read the rest of this thread...