Page 121 - Modern Analytical Chemistry
P. 121
1400-CH05 9/8/99 3:58 PM Page 104
e
p
r
t
C Chapter 5
a
h
Calibrations, Standardizations,
and Blank Corrections
In Chapter 3 we introduced a relationship between the measured signal,
S meas , and the absolute amount of analyte
S meas = kn A +S reag 5.1
or the relative amount of analyte in a sample
S meas = kC A + S reag 5.2
where n A is the moles of analyte, C A is the analyte’s concentration, k is
the method’s sensitivity, and S reag is the contribution to S meas from
constant errors introduced by the reagents used in the analysis. To
obtain an accurate value for n A or C A it is necessary to avoid
determinate errors affecting S meas , k, and S reag . This is accomplished by
a combination of calibrations, standardizations, and reagent blanks.
104
