Determination of Water Content By Karl Fischer Method in Ethyl Acetate

Product Group

Carboxylic acid esters

Section Overview

• General Information for Water Determination in Esters of Carboxylic Acids
• Methods for Water Determination in Ethyl Acetate Sample
  
• Related Materials

General Information for Water Determination in Esters of Carboxylic Acids

Esters of carboxylic acid can be analyzed analogously to the hydrocarbons according to the standard Karl Fischer method. Long-chain compounds require the addition of solubilisers, e.g., long-chain alcohols or chloroform. Unsaturated compounds can usually be titrated in the same way. Recommended methods are both the Karl Fischer volumetric titration with one or two component reagents, as well as the coulometric analysis. The latter is predominantly applied for low water concentrations (< 0.1%).

Methods for Water Determination in Ethyl Acetate sample

Ethyl acetate is easily soluble in alcoholic media. Water determination can be carried out without problems according to standard methods.

One-Component Volumetric Karl Fischer Titration

Karl Fischer Reagents:

• Karl Fischer Titrant
  Aquastar^® - CombiTitrant 5 (1.88005) - One component reagent for volumetric Karl Fischer titration, 1 mL = approx. 5 mg water
  or
  Aquastar^® - CombiTitrant 2 (1.88002) - One component reagent for volumetric Karl Fischer titration, 1 mL = approx. 2 mg water
• Solvent
  50 mL Aquastar^® - CombiSolvent (1.88008) - Methanol-free solvent for volumetric Karl Fischer titration with one component reagents
  or
  50 mL Aquastar^® - CombiMethanol (1.88009) - Solvent for volumetric Karl Fischer titration with one component reagents, max. 0.01 % water

Titration Parameters:

Default titration settings, e.g.:
I(pol) = 20 - 50 µA, U(EP) = 100 - 250 mV
Stop criterion: drift < 20 µL/min

Sample size:

10 mL

Titration Procedure:

The titration medium is first placed into the titration cell and titrated dry by means of the titrant. Then the sample is added with a syringe (exact sample weight determination by weighing the syringe before and after injection) or volumetric pipette, and the titration is started.

Two-Component Volumetric Karl Fischer Titration

Karl Fischer Reagents:

• Karl Fischer Titrant
  Aquastar^® - Titrant 5 (1.88010) - Titrant for volumetric titration with two component reagents, 1 mL = approx. 5 mg water
  or
  Aquastar^® - Titrant 2 (1.88011) - Titrant for volumetric titration with two component reagents, 1 mL = approx. 2 mg water
• Karl Fischer Solvent
  null Aquastar^® - Solvent (1.88015) - Solvent for volumetric titration with two component reagents
  

Titration Parameters:

Default titration settings, e.g.:
I(pol) = 20 - 50 µA, U(EP) = 100 - 250 mV
Stop criterion: drift < 20 µL/min

Sample size:

10 mL

Titration Procedure:

The titration medium is first placed into the titration cell and titrated dry by means of the titrant. Then the sample is added with a syringe (exact sample weight determination by weighing the syringe before and after injection) or volumetric pipette, and the titration is started.

Coulometric Karl Fischer Titration (With Diaphragm)

Karl Fischer Reagents:

• Catholyte
  5 mL Aquastar^® - CombiCoulomat frit (1.09255) - Coulometric Karl Fischer reagent for cells with diaphragm
  
• Anolyte
  100 mL Aquastar^® - CombiCoulomat frit (1.09255) - Coulometric Karl Fischer reagent for cells with diaphragm
  

Titration Parameters:

Default coulometer settings for cells with a diaphragm:
For end point indication, e.g.:
I(pol) = 5 - 10 µA, U(EP) = 50 - 100 mV
Stop criterion: drift < 10 µg/min

Sample size:

1 mL

Titration Procedure:

The Karl-Fischer reagent is placed into the cathode and anode compartments of the titration cell with a diaphragm. The coulometer is started, and the solvent is titrated dry. After preliminary titration and stabilization of drift, the sample is injected into the titration cell with a syringe (exact sample weight determination by weighing the syringe before and after injection), and the water determination is started.

Coulometric Karl Fischer Titration (Without Diaphragm)

Karl Fischer Reagents:

• Working medium
  100 mL Aquastar^® - CombiCoulomat fritless (1.09257) - Coulometric Karl Fischer reagent for cells with or without diaphragm
  

Titration Parameters:

Default coulometer settings for cells without a diaphragm:
For end point indication, e.g.:
I(pol) = 5 - 10 µA, U(EP) = 50 - 100 mV
Stop criterion: drift < 10 µg/min

Sample size:

1 mL

Titration Procedure:

The Karl-Fischer reagent is placed into the titration cell without a diaphragm. The coulometer is started, and the solvent is titrated dry. After preliminary titration and stabilization of drift, the sample is injected into the titration cell with a syringe (exact sample weight determination by weighing of syringe before and after injection), and the water determination is started.