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.
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