Water Content of 5.55 % Water Oven Standard

This note describes volumetric Karl Fischer titration of a 5.55 % oven water standard using an autosampler InMotion KF Flex autosampler for water gas phase extraction connected to a V30S volumetric KF-titrator. For the same application, the Excellence line titrators T7 or T9 can also be used.

Background:

Gas phase extraction principle: Air is aspirated by an air pump and passed through a drying unit filled with silica gel and subsequently through a drying unit filled with molecular sieve. A digital gas flow control will regulate the flow rate (typical 80 – 150mL/min) that is defined in the titration method. The dry air will extract the water from the sample and transfer it into the titration cell.

The 5.55% oven water standard is a water standard that is thermally stable up to 250 °C. Its recommended water gas phase extraction temperature is 220 – 230°C. This standard is used to verify that the Karl-Fischer equipment including the oven is working properly.

For the mean value and repeatability one has to define the acceptance criteria for the system check. For this system the acceptance criteria were defined as follows:

Recovery: 95 ─105%

Repeatability: < 3.0%

The Application Includes:

• Introduction
• Sample Preparation and Procedures
• Chemistry
• Instruments and Accessories
• Method in Detail
• Results and Remarks

And method files ( .lmt and .xml) for direct import and implemention on the instrument