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

Titrant Sample

Start

Titration

Titrant Titrant + Sample

Endpoint

Titration

Titrant Titrant + Sample

End

- optical detection

- manual control

- manual addition

Titrant

Color indicator

Principle of a Manual Titration

All in one!

• Dosing

• Measuring

• Controlling

• Evaluation

Titrations Modes

• Set Endpoint TitrationSET

• Monotonic Equivalence point TitrationMET

• Dynamic Equivalence point TitrationDET

• Karl Fischer TitrationKFT

Set Endpoint Titration

volume

endp

oint

Signal[pH/mV]

Monotonic Equivalence Point Titration

equivalence point

Signal[pH/mV]

volume

equivalence point

Dynamic Equivalence Point TitrationSignal

[pH/mV]

volume

400.00

800.00

0.00 3.00

400.00

800.00

0.00 3.00

Volume increment• In MET mode the steps are always the same• In DET mode the steps are calculated by the Titrando

MET Mode

pH

V [mL]

EP1

pH

V [mL]

EP1

DET Mode

Karl Fischer Titration

volume

Endpoint

Signal[g/min]

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 curve

universal 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

stirrer

buretelectrode

Arrangement

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

• When do I have to determine a titer?frequently

• How is the titer determined?With titrimetric standards

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

EP1

6,0

6,5

7,0

7,5

8,0

8,5

0,0 0,5 1,0 1,5 2,0 2,5 3,0 3,5 4,0 4,5 5,0 5,5 6,0

DET Mode

pH

V [ml]

EP1

6,0

6,5

7,0

7,5

8,0

8,5

-0,0 0,5 1,0 1,5 2,0 2,5 3,0 3,5 4,0 4,5 5,0 5,5 6,0

DET Mode

pH

V [ml]

• 4 default• 0 high density

• 9 low density

Stop conditions

Evaluation

Calculation

Report

Result report

Curve report