CalibrationWindow- Methods
Recalibration type
Ei
The Method button opens the Re–
calibration Type
window which allows the
selection of one of six formulas used to
draw the calibration curve. The algorithms
are described below and corresponding
calibration statistics are shown.
In the following:
X
tstne sum of
the externa l measures over the calibration lev–
ets
Y
is
the sum of the corresponding areas at those calibration
levels
n is the number of active calibration levels
Several other sums are used. for instance:
X2
is
the sum of the squares of the external measures
Y4
is
the sum of the (area to the4th power)
XY
is
the sum a/the (external measure >area)
X2Y
is
the sum of (external measure squared ' area)
YIX
is
the sum of the (area
I
external measure) etc.
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The resulting calibration curve is defined as
Single line:
Single line through origin:
where:
x is external measure
y is area
A=( (XY · n) -(X "Y)
l i D
B=( (X "Y2) · (XY· X)
li D
D=«X2"n) - {X"X)
EPA rules allow Ihe use of Single line Fit provided that the
standard deviation of calibration factors is <20%,
y=AY.+B
where:
x is extema!measure
y is area
A=(YIX)/n
There is no resulting formula here, just interpolation between
the levels, and the origin. There must be at least one calibration
level.
y=AY.
Multiple line segments;
The resulting calibration curve is defined as
Notes:
The resulting factor is therefore the average of the calibration
factors at the calibration levels. Note: any expl icit calibration
level point at x=Ois ignored (and n is reduced by 1). There must
be at least one calibration level. not including any level al )(=0.
Noles:
This is a least squares fit algorithm over tne calibration levels.
A point at (0.0) is also assumed (by incrementing n) unless
Ihere is already a value at :<-0, or if [StatisticsJR2lncludeZero is
set to0 in the PEAKWIN.lNI file. Theremust
be
at least 2
can–
bration levels
