Karl Fischer titration for water content of pasta

The water content of pasta (noodles, spaghetti, etc) can be determined by volumetric Karl Fischer titration.

The water content of pasta (noodles, spaghetti, etc) can be determined by volumetric Karl Fischer titration.

Pasta with a low water content of about 10% can be stored for many years.

Pasta containing much more than 12% of moisture has a considerably shortened shelf life as it can become musty and mouldy.

Prior to analysis the pasta is ground up as finely as possible in a cooled laboratory mill.

As the sample could heat up during grinding (resulting in water loss), cooling is crucial for obtaining correct results.

Extraction of the water from the powdery sample is accelerated by adding formamide and working at 50 C.

This considerably shortens the time required for the Karl Fischer titration.

Water determination (also called moisture determination) is, together with the measurement of the pH value and acid-base titrations, one of the most frequently performed analyses in laboratories around the world.

This is not really surprising, as the water content directly influences the quality, processability, shelf life and stability of a wide range of products.

Various physical and chemical methods are used to determine the water content.

Among these, the Karl Fischer titration has established itself as a reference method for general use.

It is characterized by its high specificity and precision and works over a wide concentration range from ppm up to 100%.

An additional advantage are the short determination times.

This monograph first describes the basics of Karl Fischer titration.

It covers not only the KF reagents, chemical reactions, volumetric and coulometric titration as well as the different detection methods, but also deals with aspects such as interfering side reactions and sample preparation techniques.

The second part of the monograph contains detailed working instructions for the determination of water in different samples and covers more than 900 substances.

The spectrum ranges from raw materials through cosmetics, pharmaceuticals, foodstuffs and plastics up to gaseous samples.

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