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Chemical Analysis
Figure 12 Semilogarithmic Calibration Curve
Absorbance
0
Tens
0
–
10
2.30
20
1.61
30
1.20
40
.92
50
.69
60
.51
70
.36
80
.22
90
.11
Chemical Analysis
Page 46
100
80
60
50
40
30
20
10
To convert %T readings to concentration, prepare a table such as Table 9 and
select the appropriate line from the "%T Tens" column and the appropriate
column from the "% T Units" columns. The %T Ten value is the first number of
the % transmittance reading and the %T Units value is the second number of the
% transmittance reading. For example, if the instrument reading was 46%, the 40
line in the %T Tens column and the 6 column in the %T Units would be selected.
The cell where these two intersect (0.78 mg/L) is the iron concentration of the
sample.
Table 9 Calibration Table
1
2
3
–
–
–
2.21
2.12
2.04
1.56
1.51
1.47
1.17
1.14
1.11
.89
.87
.84
.67
.65
.64
.49
.48
.46
.34
.33
.32
.21
.20
.19
.09
.08
.07
mg/L IRON
Absorbance Units
4
5
6
–
–
–
1.97
1.90
1.83
1.43
1.39
1.35
1.08
1.04
1.02
.82.
.80
.78
.62
.60
.58
.45
.43
.42
.30
.29
.28
.17
.16
.15
.06
.05
.04
7
8
9
–
–
–
1.77
1.72
1.66
1.31
1.27
1.24
.99
.97
.94
.76
.73
.71
.56
.55
.53
.40
.39
.37
.26
.25
.24
.14
.13
.12
.03
.02
.01
5940022ChemAnal.fm
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