Chemical Analysis
Chemical Analysis
5940022ChemAnal.fm Page 49
Figure 13 Selecting the Best Wavelength
Adapting a Buret Titration for Use With a Digital Titrator
Any standard titration procedure that uses a buret can be adapted to the Digital
Titrator by using the following procedure.
1. From Tab le 12 on page 50, select a titration cartridge having the same active
ingredient as the buret solution.
2. Determine the approximate number of digits required. The Digital Titrator
dispenses 1 mL per 800 digits on the counter. Using the following equation,
determine the digits required for your buret method.
Where:
N
t
= Normality of buret titrant
mL
t
= milliliters of buret titrant required for an average titration
N
c
= Normality of Digital Titrator cartridge.
If the number of digits required is within the range of 70 to 350, you can use the
procedure as written, substituting the Digital Titrator directly for the buret.
Or, if the number of digits is outside of this range, make the following
modifications:
a. If the number of digits required is greater than 350, decrease the sample
size to save titrant.
b. If the number of digits required is less than 70, increase the sample size to
increase precision.
c. If the sample size is altered, adjust the amount of buffering or indicating
reagents by the same proportion.
500 505 510 515 520
0.0
1.0
400 450 500 550 600 650 700
Wavelength (nm)
Absorbance
Digits Required
N
t
mL
t
× 800×
N
c
---------------------------------------=
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