52
Amplification Curves
Problem
Cause
Solution
4
Delayed Cq values
a. Decreased PCR
efficiency
Design specificity: Confirm
there are no mismatches
between target and
primer/probe sequences by
performing a BLAST search
to confirm specificity or
target and assay
sequences. Also confirm
that the primer/probe does
not span a SNP site
Reaction setup: Confirm
whether reaction efficiency
has decreased over time by
re-running a previously
working assay. If not assay
specific, confirm proper
storage of master mix
and/or template
Instrument: Confirm that
the cycling temperatures
and time parameters are
correctly set
b. Master mix differences
Test different master mixes
with the same protocol,
assay design, and reaction
components. Confirm assay
reproducibility
c. Sample component
inhibiting PCR
Dilute sample or change
extraction procedure
5
Cq values are very
early (<15)
a. Template concentration
too high
Dilute sample as necessary
to obtain Cq values greater
than 15