Melting point and amplicon size

[3pi]

Hello,

I'm thinking about discrimination of amplicons of different sizes, say 
about 5 bp at least, by analysis of melting curves in a multiplexed 
sybr-green real time pcr assay.

I've red about snp detection by melting point analysis of amplicon sizes 
  up to 160 bp

I'm thinking if there is any theoretical upper limit in amplicon sizes 
for the detection of small base number differences, and how to calculate 
it ..

any hint is welcome,
thnx and regards.

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3pi
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