During normal system operation, helium carrier gas circulates within the analytical circuit which consists of a combustion reactor for CHNS and N/Protein, or a pyrolysis reactor for Oxygen. The carrier gas brings the products of combustion, or pyrolysis to a gas chromatographic separation column and TCD detector for CHNSO analysis, or a multidetector system for N/Protein determination.
C/H/N/S Elemental Analysis
At the start of the analytical cycle the helium carrier gas is switched to a volume of oxygen which is chosen by the operator depending on the size and composition of the sample. The samples are dropped sequentially into the combustion reactor prior to the arrival of oxygen. The sample and tin capsule react with oxygen and combust at temperatures of 1700-1800 °C and the sample is broken down into it’s elemental components, N2, CO2, H2O and SO2. High performance copper wires absorb the excess oxygen not used for sample combustion. The gases flow through the gas chromatographic (GC) separation column which is kept at a constant temperature (+/- 0.1 °C). As they pass through the GC column, the gases are separated and are detected sequentially by the TCD. The TCD generates a signal, which is proportional to the amount of element in the sample. The EAS software compares the elemental peak to a known standard material (after calibration) and generates a report for each element on a weight basis. For Continuous Flow Isotope ratio Mass Spectroscopy, the separated gases are carried to the mass spectrometer interface and into the MS source.
Helium carrier gas circulates through the analytical circuit, which consists of a pyrolysis reactor which is filled with a special nickelized carbon wool contact material heated to 1080°C, a trap for acidic gases formed by the pyrolysis, a GC column which will separate the gas mixture, and a TCD. Samples are dropped automatically into the pyrolysis reactor, break down and the released oxygen reacts with the nickel carbon wool to form CO (2C + O2 = 2 CO) and N2, if present in the sample. The mixture of N2 and CO gases flow through the gas chromatographic (GC) separation column which is kept at a constant temperature (+/- 0.1 °C). As they pass through the GC column, the gases are separated and the CO peak is detected by the TCD. The TCD generates a signal which is proportional to the amount of CO in the sample. The EAS software compares the CO peak to a known standard material (after calibration) and generates a report for oxygen concentration on a weight basis.