Basics of Titration
by
Michael Margreth
Basics
• One of the oldest analytical methods
• Based on chemical reaction
• Determination of the volume of a standard solution
(titrant)
• Standard solution contains a defined number of
molecules
• Measuring volume = counting molecules
• TITRATION MEANS COUNTING!
Titration
Start
Titrant
Sample
Titration
Endpoint
Titrant
Titrant + Sample
Titration
End
Titrant
Titrant + Sample
Principle of a Manual Titration
Titrant
- optical detection
- manual control
- manual addition
Color indicator
All in one!
• Dosing
• Measuring
• Controlling
• Evaluation
Titrations Modes
• Set Endpoint Titration
SET
• Monotonic Equivalence point Titration
MET
• Dynamic Equivalence point Titration
DET
• Karl Fischer Titration
KFT
Set Endpoint Titration
Signal
[pH/mV]
volume
Monotonic Equivalence Point Titration
Signal
[pH/mV]
equivalence point
volume
Dynamic Equivalence Point Titration
Signal
[pH/mV]
equivalence point
volume
Volume increment
•
•
In MET mode the steps are always the same
In DET mode the steps are calculated by the Titrando
MET Mode
DET Mode
800.00
pH
pH
800.00
EP1
EP1
400.00
0.00
V [mL]
3.00
400.00
0.00
V [mL]
3.00
Karl Fischer Titration
Signal
[mg/min]
volume
Which mode for which titration?
SET
MET
DET
KFT
defined
endpoint
slow reaction
quick reaction
Karl Fischer
Titration
non-aqueous
titration
duration has
priority
non S-shaped
universal
curve
method (90%)
Endpoint evaluation
tangent method
circle method
derivative method
Titration steps
• sample preparation (homogeneity)
• right electrode choice
• possibly electrode conditioning
• titrant preparation
• titer determination
• buret/ sample size choice
• correct arrangement in titration vessel
• stirrer rate
• method parameters
• results calculation
• report
Arrangement
stirrer
electrode
buret
Titer
• What is a titer?
Correction factor
• Why do we need the titer?
To know the exact concentration of the titrant
• What is the unit?
none
• How is the titer determined?
With titrimetric standards
• When do I have to determine a titer?
frequently
Advantages
•
•
•
•
•
•
•
Absolute method
Easy to carry out
Carried out very rapidly
Versatile method
Highly reproducible and correct results
Can be automated
economical
Hardware definition
System
Titrant definition
Sensor definition
Method definition
Parameters
Titration method
Titration parameters
Sensor
Dosing device
Stirrer
Direct parameters
Direct parameters
Start conditions
Titration parameters
User defined parameters
Measurement density
•
•
4
0
default
high density
•
9
low density
DET Mode
DET Mode
8,5
8,5
8,0
8,0
7,5
pH
pH
7,5
EP1
7,0
EP1
7,0
6,5
6,5
6,0
6,0
0,0
0,5
1,0
1,5
2,0
2,5
3,0
V [ml]
3,5
4,0
4,5
5,0
5,5
6,0
-0,0
0,5
1,0
1,5
2,0
2,5
3,0
V [ml]
3,5
4,0
4,5
5,0
5,5
6,0
Stop conditions
Evaluation
Calculation
Report
Result report
Curve report