In article <2vrtgo$edn at strauss.udel.edu> John H McDonald,
mcdonald at strauss.udel.edu writes:
>This procedure removes unincorporated primers and nucleotides well enough
>that the DNA can be used for sequencing. We have used it on PCR products
>that are 300 bp and larger; I don't know how much smaller you can go
>before the DNA doesn't precipitate.
I have been able to precipitate PCR products down to about 110 bp. That
is the shortest fragment I have amplified.