Elemental Analyzer

Elemental analysis is an experiment that determines the amount (typically a weight percent) of an element in a compound. A CHN/O Analyzer is a scientific instrument which can determine the elemental composition of a sample. The name derives from the three primary elements measured by the device: carbon (C), hydrogen (H) and nitrogen (N) and oxygen (O). Sulfur (S) can also be measured. The Elemental Analyzer (Exeter Analytical Inc.model: CE 440) (Figure 1) was established in the Core Lab (201D) in 2007 with the DRDO grant of the Institute.

Basic Principle:

The capsule is injected into a high temperature (1000°C) furnace and combusted in pure oxygen under static conditions. At the end of the combustion period, a dynamic burst of oxygen is added to ensure total combustion of all inorganic and organic substances. The resulting combustion products pass through specialized reagents to produce carbon dioxide (CO₂), water (H₂O) and Nitrogen (N₂) and oxides of nitrogen. These reagents also remove other interferences including halogens, sulfur and phosphorus. The gases are then passed over copper to scrub excess oxygen and reduce oxides of nitrogen to elemental nitrogen. After scrubbing, the gases enter a mixing volume chamber to ensure a homogeneous mixture at constant temperature and pressure. The mixture then passes through a series of high-precision thermal conductivity detectors, each containing a pair of thermal conductivity cells. Between the first two cells is a water trap. The differential signal between the cells is proportional to the water concentration, which is a function of the amount of hydrogen in the original sample. Between the next two cells is a carbon dioxide trap for measuring carbon. Finally, nitrogen is measured against a helium reference (Figure 2).

Unique Features:

With unique combination of both static and dynamic combustion, the CHN/O/S instrument can combust the widest range of sample type, from volatiles to refractories. Fully automated. Rapid analysis for high productivity - analysis time of less than 5 minutes per sample. Stable thermal conductivity detector provides linear response with superior precision and accuracy. Horizontal sample injection removes interfering residue between each sample run.

Location:

Department of Chemical Engineering,Core Lab 201D,
IIT Kanpur

Contact:

Prof. Nishith Verma

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Figure 1

Figure 2