storing pcr samples - (Jul/13/2008 )
Hi everybody,
I use an Eppendorf mastercycler. At the end of every pcr programme I have included a 4 degree hold step so that I can leave my samples in the pcr machine overnight. I just want to know if its good for the samples to remain in the machine at 4 degrees for many hours after completing the programme. Will this affect my samples in any way. Thank you.
I use an Eppendorf mastercycler. At the end of every pcr programme I have included a 4 degree hold step so that I can leave my samples in the pcr machine overnight. I just want to know if its good for the samples to remain in the machine at 4 degrees for many hours after completing the programme. Will this affect my samples in any way. Thank you.
It is okay. That's why they have this option.
It is sloppy and risky however, somebody may trip your samples, switch off the machine etc.
Why don't U instead just put it in the refrigerator? = 4 deg C. 
(That's U in the pic, cell counter?)
sometimes when the pcr programme gets completed in the middle of the night, i may not be around to put the samples in the refrigerator. thats why i have included this step in the programme. will the dna get degraded if it remains in the machine for more than 6 or 7 hours at 4 degrees.
No it won't.
Your samples will be OK, but running these cyclers for extended periods at low temperatures is hard on the machines. I usually end my programmes with a 10-second step at 10 degrees, just to cool the block down, and then end the programme. DNA is quite stable, and sitting at room temperature even overnight will not do them much harm.
I agree with wbla... you shouldn't keep your PCR machine cooling to 4.C overnight, ... if you are really afraid, cool to 14.C only... But it's useless in my opinion. You just have to think of what you are going to do with your PCR product afterwards... and if it's really precious.
thanks for all the replies. so in case i leave my pcr machine running overnight is it good to set the last step as HOLD 14 DEGREES rather than 4 degrees. Can someone please say why its not good for the machine to remain at 4 degrees for long.
May be afraid that the machine will break down. 
I used to set zero degree hold if my samples would finish in the night. But, if I am around and I need to keep the samples till I run the gel, I put them in the refrigerator.
Zero degree should not damage and should be safe. May be U should check with the lab technician if U r allowed to keep it at zero for few hours. If they say yes, go ahead. 
I knew it from the manufacturer of PCR machine...
they recommend to set your last step at 10C, instead of 4C if you wish to leave your reaction inside machine for overnight.
this will not burden the machine and prolong teh lifespan of your machine.
the colder the machine is trying to maintain, the harder the machine will have to work - imagine you work too hard overnight everyday... you'll break down too.