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PCR blood old samples - (Nov/28/2004 )

Hi everyone,
Please, I have a problem and I need help! I have several blood samples obtained since 2002. These samples were mantained at 4ºC for several months, and at -20 ºC since may 2004. I´beem trying to extract DNA from these samples with DNAzol and the amount obtained was about 0.5 microgram/microliter from 100 microliter of blood. the samples were collected in EDTA tubes.
My question is: it is possible to perform PCR with these samples? The time of storage could degrade the DNA? the quantification in spetrophotometer could show contamination with proteins or other compounds masquerading the amount of DNA quantificated?
Thanks a lot for your attention!



Hello! The problem is less the freezing but the storage at 4 °C. But I do not think ist is absolutely unrealistic, just try. You will probably will be surprised about the good results. But you have to be shure that all EDTA is removed. Further more it depends on the amplicon size you want to get, about 200 bp should be no problem. Of course the DNA will be degraded. Have you determinded the ration A 260 nm to A 280 nm? Than you will get more Information about possible contamination with organic solutions (phenol) or proteins.


try to run your isolated DNA on 1 or 2% agarose gel. if you will see one band, your DNA is not degraded. if you will see ladder it is.. but even on degraded DNA is possible to run PCR.. just try it. good luck!