limit of detection

in analysis
The limit of detection, expressed as the concentration, c L, or the quantity, q L, is derived from the smallest measure, x L, that can be detected with reasonable certainty for a given analytical procedure. The value of x L is given by the equation
x L = x ̄ bi + k s bi
where x ̄ bi is the mean of the blank measures, s bi is the standard deviation of the blank measures, and k is a numerical factor chosen according to the confidence level desired.
Orange Book, p. 5