Dear Priya

it would be good to see the actual numbers from your nanodrop readings so I could explain how to dilute your DNA sample to ensure it is 0.5ug/ul (0.5mg/ml). Have I understood your question correctly ?

Hi,

I am afraid that if i had understood what you wanted. I would rather take chance to put some suggestion if i am right in guessing. First, It completely depends on what kit you have used (for example we use 50ul of TE to get conc. more than 1ug/ul in QIAgen kit), quality of the ethanol you used, may be you can use sodium acetate 1/10th vol while making precipitation to make sure that you are up from the mark. Second, I would say why you are not using drier for the sample once you got the low conc. May be you could consider the lyophilization of the sample.

Thanks

Imtiaz

Hi Priya,

There is a great little formula that I use almost daily for calculating concentrations/dilutions (memorize this!!) :  C1V1=C2V2  (starting concentration X starting volume = final concentration X final volume).  But you haven't given all the info such as the concentrations from your NanoDrop? C1 would be the Nanodrop reading. C2 would be the 0.5ug/mL (make sure units are always the same). Without all the info I'm guessing that V1 would be the volume before precipitating.  Solve for V2 to find final amount to redissolve the DNA pellet in.   Not sure this is what you were asking for but a good formula to be aware of.          Cheers, Susan

 Thank you Laurence,Susan and Imtiaz, I appreciate your timely help. Basically we do extraction manually, not using kit. I can explain more clearly what I do.After receiving 5ml blood I pour into 20ml sucrose triton solution then make up to 40ml with millipore water then centrifuge , to the pellet add lysis buffer and proteinase K. After overnight incubation , I add salt and take out the supernatant and dissolve  in 100% ethanol to pool out the DNA . To that pooled out DNA I have to make a decision how much TE to be added for each assay like FRAGILEX assay southern atleast need .5ug when do the OD otherwise  when doing southern I have to take more volume. For RFLP bench below .5ug/ul is fine . This decision how I make using the formula as Susan suggested or it is by experience.

Once again thank you very much for your help.

Thanks,

Priya.