Select Axes - Awareness Technology Stat Fax 4200 Operator's Manual

2.5.4.3 – Select Axes
Axes selections include linear-linear, ln (= natural log)-linear, linear-ln, or ln-ln
calculations. A logit-log calculation is also available. Absorbance, or ln of (1000 *
absorbance), is always on the "Y" axis. Concentration, or ln of concentration, is always on
the "X" axis.
Calculation
"Y= ABS, X=CONC"
"Y=Ln (1000*ABS), X=Conc"
"Y=ABS, X=Ln(Conc)"
"Y= Ln (1000*ABS), X=Ln(Conc)"
"Y= Logit(Abs), X= Log(Conc)"
Refer carefully to the Reagent Kit product insert for correct selection.
NOTE: Remember log of 0 is undefined so do not set concentration to 0 (zero) on a
logarithmic scale.
Point-to-Point and Regression modes require at least two standards, Cubic Spline
requires at least three standards.
40 Stat Fax

SELECT AXES

Y=Abs X=Conc
Y=Ln(1000*Abs) X=Conc
Y=Abs X=Ln(Conc)
Y=Ln(1000*Abs) X=Ln(Conc)
Y=Logit(Abs) X=Log(Conc)
Both the absorbance data (y) and the
concentration data (x) are linear.
The natural log of the absorbance is plotted
against the concentration. The absorbance
values are multiplied by 1000 before taking the
logs.
Absorbance is plotted against the natural log of
the concentration.
The natural log of the absorbance is plotted
against the natural log of the concentration.
Select to calculate unknowns using the
equation: Abs Logit = Ln [(sample/0 cal) / 1-
(sample/0 cal)]
® 4200 Operator's Manual Doc. 4200 Rev. K
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Explanation