Carlo Erba EA 1110 CHNS-O

EA 1110 CHNS-O is an elemental analyzer dedicated to the simultaneous determination of the amount (%) of carbon, hydrogen, nitrogen and sulfur in organic and inorganic chemical compounds and in substances of different nature and origin, be they solid or liquid samples.
The analytical method used develops on subsequent steps: at first the sample undergoes a controlled combustion, immediately followed by catalytic oxidation and reduction. Gases produced during this first step are separated by gas chromatography and then passed through a thermal conductivity detector, that for each combustion gas generates an electric signal, proportional to the amount of gas going there through, that conveniently processed gives the percentage composition of elements.
The technique used to analyze the sample is the Dynamic Flash Combustion that consists in what follows: the sample weighed in a tin capsule and placed in the autosampler is dropped into a quartz tube kept at 1000 °C and with helium continuously flowing there through.
At startup carrier gas is enriched with a known quantity of oxygen and the sample is dropped into the tube a few moments before oxygen arrives, thus a violent exothermal reaction occurs (flash combustion). Under these favorable conditions even thermally resistant substances are completely oxidized.
The gas mixture developed by oxidation passes on the catalytic layer present in the quartz tube: on the WO3 layer gases are further oxidized, on the Cu layer nitrogen oxides and sulphuric anhydride that eventually formed are reduced to elemental nitrogen and sulphurous anhydride, while oxygen excess is cut off (stopped).
The gas mixture is transferred into the gas chromatographic column where single components are separated in the following order: N2, CO2, H2O, SO2.
Thanks to the TCD detector electric signals are obtained that, conveniently processed by Eager 200, supply the percentage composition for each element.