Detection limit is a measure of the smallest concentration
which can be determined with a specified precision or
reproducibility. Most frequently, the specified precision is
defined in terms of the concentration producing a signal
equivalent to three times the standard deviation of a series
of blank (baseline) readings or readings for a standard with
a concentration close to the anticipated detection limit. This
definition is equivalent to a 99% confidence level. That is,
the answer obtained under these conditions will be correct
99 times out of 100.