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PCR contamination? - (May/15/2005 )

Hi everyone,
Lately I have got a strange problem in my pcr. I get a faint product in my negative control also and of the same size, while some of my positive control does not work at all. The problem was not there before and I am using the same batch of primers and everything. I tried to make everything fresh but still the problem persists. I am using the pcr beads
Any help will be highly appreciated.



hi kim, it maybe worth your while to get some new beads

could you post an image to the board so we can see what it looks like? Could it be primer dimer?



Thanks ,When I take the picture it is not visible since it is very faint but when I view it in the UV transilluminator I can easily see it. I guess it is not a primer dimer since it is at the same place as the expected product. I have changed everything but still I canĀ“t get rid of it.



i m facing the same problem,getting target band in negative control but not sometimes in positive control.i m doing a nested pcr and getting target bands in negative control of primary pcr and when i use this neg ctl. as a template for secondry pcr i get a very prominent secondry pcr product.
interestingly i dont get the sec band in the negative ctl of secondry pcr itself.
i m suffering from this problem for last few months and could not solve even after changing all reagents and uving the surfaces,etc etc.
can anybody help ?