quiagen lambda preps

[Large Hearted Boy]

Hi all,

In an effort to increase my Lamda yields, I processed twice the 
recommended amount of liquid lysate to be used per prep. I doubled up the 
amount of L1 and L2 used, and after the PEG precipitation with L2, I 
carried on as if I hadn't doubled the amount of lysate used. When I did 
the Isopropanol precipitation, I immediately got a DNA clot that looked 
suspiciously like genomic DNA. when I ran it out on a gel, although the 
yield was great, there did indeed seem to be some genomic contamination. 
Digests of the said DNA bore this out, as I got a tremendous smear, along 
with the Lambda bands I was expecting.  At first I wondered whether using 
twice the amount of lysate could have caused the problem. I just wonder if 
maybe the L1 has been sitting around too long and the DNAse I has gone bad.
Could I add some DNase I to the L1 I still have ?

thanks for any help you can provide me,

     Ed Taboada
  Dept. of Biology
University of Ottawa
       Canada