Molecular Devices SpectraMax Paradigm User Manual page 32

SpectraMax Paradigm Multi-Mode Detection Platform User Guide
Detection Limit
The detection limit is the smallest sample concentration that can be measured reliably above
the blank. Determining the detection limit requires taking a number of blank measurements
and calculating an average value and standard deviation for the blanks. The detection
threshold is defined as the average blank plus three standard deviations. If the average
sample value measures above the threshold, the sample can be detected at a statistically
significant level.
The detection limit can be described by the following equation:
Det Limit =
where conc
blank replicates, and blank and Std are average values of the replicates for the blank and
standard wells.
Determining the detection limit for an assay requires multiple blanks to calculate their
standard deviation.
Linearity and the Linear Dynamic Range
Within a wide range at moderately high concentrations, blanked raw data is proportional to
the quantity of label in a sample.
The linear dynamic range (LDR) is defined by:
LDR = log
where LDR is expressed as a log, and max conc lin is the highest concentration in the linear
range that can be quantified.
When the standard curve after blank reduction is not linear in concentration at the lower
end, there might be an incorrect or contaminated blank.
32
3 Stdev
blank
std – blank
conc
std
is the concentration of the standard, StDev
std
( )
max conc lin
10 detec on limit
is the standard deviation of the
Blank
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