Hey I got it. I did kinda what you did. I am all new to programming and so was a bit messed. Well, I used the following modification and it worked.

foreach $bar($foo->identifiers()){
     if ($bar =~ /PMID: (\d+)/)
         {
            print FH "$1\n";
         }
        }
[download]

Thank you for your help. Sammed