is there a loss of volume after pcr? - (Nov/30/2006 )
hi!
i wanted to know that is there some loss of volume after the pcr reactions? if yes how much and what should be done to avoid the loss? i dont do any layering so should i do that? 
Yes liquid in PCR reaction can evaporate. In early days of PCR, people use mineral oil to prevent evaporation which is very effective but troublesome. When heat lid was invented, mineral oil is less used. With heat lid, you may still get 5% evaporation, but you avoid the annoying oil.
i wanted to know that is there some loss of volume after the pcr reactions? if yes how much and what should be done to avoid the loss? i dont do any layering so should i do that?
Depends also on quality of pcr tubes, some have very tight lids other not, you have to try out or ask for samples.
Also some users (esp new students) don't get it to close them completly...
In all honesty I don't think that there is much you can do to avoid volume loss. The sample is regularly being heated to 95-98C so evaporation is inevitable. Definitely ensure the lids are on tightly. Some wells in the PCR block tend to get hotter than others so be aware of that too. I'm not sure if it is particular wells that get hotter or tubes on the outside of a bunch of samples but that effect definitely exists. Also be aware that it is basically just water that is evaporating. Your DNA will still remain in the solution no matter what volume you have left at the end. Water is only H2O and DNA is too heavy to be evaporated.
its a very lower amount of loss, i think u could avoid this...........or u have no way bu avoid it
ya there will definitely be some loss by evaporation....... but its generally negligible....and the rxn works fine even if theoretical change in buffer conc in the rxn......and shudnt bother much... .. but then if under ur current conditions where u cant change the machine (with goo heated lid) or the tubes (good tight lids) while experiencing a higher loss of rxn volume resulting in un-uniform amplification across samples and replications, then u need to use a drop of mineral oil.....it certainly checks the evaporation loss.
gud luk