Water in Various Gases – Fully Automated Determination by Coulometric Karl Fischer Titration

4 Oct 2015
Lois Manton-O'Byrne, PhD
Executive Editor

Water is an unwanted constituent of all kinds of gases. Precise determination is therefore a must, e. g., in medical gases, noble gases, process gases, and welding gases. The 875 KF Gas Analyzer is a highly robust solution for this kind of analysis, combining precise sampling with the accuracy of coulometric Karl Fischer titration in a fully integrated, software controlled analyzer.

Water can be determined with various analytical techniques at trace levels. However, water in gases is a particular challenge: Most of the feasible methods need to be calibrated and can only determine the water content indirectly. In contrast, Karl Fischer titration measures the absolute amount of water in the gaseous matrix. Moreover, results do not tend to drift, as the reagent is exchanged at regular intervals. As Karl Fischer titration is a primary method, the sensor does not need to be calibrated either. Detection limits of the method lie in the single-digit ppm range (µg water/g gas).

The 875 KF Gas Analyzer is controlled by tiamo™, the leading control and database software for titration. The analyzer module consists of a robust sampling system with a mass flow controller at its heart. Moreover, the system is equipped with an integral evaporator for liquefied gases, an inlet filter to separate out particles, and an oil filter. The titration vessel with indicator and generator electrode (with diaphragm) and an 851 Titrando coulometer are also included in the module. Safety is provided by the strict separation of the gas-carrying system and the electronic area.

tiamo™

Metrohm AG

tiamo™ is a control and database software for titrators and dosing devices as well as for complete laboratory automation, including client-server systems. The name tiamo™ stands for «titration and more» – tiamo™ can do more than just titrate. tiamo™ is a titration network (NTDS = Networked Titration Data System). The modern user interface makes it easy for you to familiarize yourself with tiamo™. All the commands and controls are to be found where you expect them to be. Using the tiamo™ main symbol bar you can access the five program parts of tiamo™ directly and easily. Each program part includes the menu and symbol bars for the specific workplace as well as the main window. Depending on how you have configured the access rights, these buttons may be visible or concealed for individual users.Features: New, appealing software interface Freely configurable desktop thanks to new Layout Manager Powerful report generator Automatic database backup Graphical method editor Easy incorporation of instruments and accessories

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851 Titrando Coulometer

Metrohm AG

The coulometric Karl Fischer Titration is the method of choice for low level water determinations (10 μg … 10 mg absolute water content) in liquid, solid and gaseous samples. As it is an absolute method a titer determination is not necessary. With the 851 Titrando coulometric titrations are carried out straightforwardly and quickly.

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875 KF Gas Analyzer

Metrohm AG

The 875 KF Gas Analyzer is a completely configured system, including predefined methods for automatic coulometric water content determination in liquefied and permanent gases. • Complete system with durable components for high flexibility and for pressures up to 40 bar • Separation of the gas-carrying system from the electronics and the power supply • Input filter for avoiding the introduction of particles by the sample • Integrated vaporizer for liquefied gases • Oil filter for removing oil residue • Precise gas measurement with mass flow measurement instrument • Automated analysis process • Predefined analysis methods • All components are integrated in a single housing

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