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Description:
The CHNS content is determined using the Pregl-Dumas method where your sample is prepared, introduced into the combustion chamber and burned at high temperature 925°F under pure oxygen. The resulting gas mixture and helium carrier gas pass through various reductive and catalytic zones to convert the gas mixture into CO2, H2O, N2, and SO2. The gasses are separated using gas chromatography and quantified with a thermal conductivity detector. Elemental analysis has been used for many decades in characterizing sample composition and purity. The machine can handle a wide variety of samples from solids, liquids, viscous samples, soils, and pharmaceutical agents.
Sample Purity:
The determination of the mass percentage of CHN elements in the sample is based upon the direct weight of the material sampled. Therefore, it is very important that samples are dry, free of foreign substances such as solvent, dust, rust, hair, aluminum foil, parafilm and paper filter fibers (the most common contaminant). The lab needs to know if and what metals, halides, or other interferences might be contained in the sample.
Potential problems:
In CHN mode, the accuracy is ±0.3%. Samples must be very pure and have the correct chemical structure to pass elemental analysis. If there are any solvents or moisture trapped in the sample, the accuracy of the results will be affected. Also, if the sample is not homogeneous, duplicate runs will not agree to within ±0.3%.
If a sample is extremely volatile, it may lose mass due to evaporation after it has been weighed out, even if it is crimp‐sealed in a special volatile sample pan. This can also cause the results to be inaccurate.
Some compounds are inherently difficult to combust completely. Incomplete combustion can also cause inaccurate results. In this case, the sample could be re‐run under different conditions, with an added oxygen boost, or with the addition of a chemical combustion aid such as vanadium pentoxide.
Other Requirements:
As the calibration of the instrument requires the theoretical percentage of each element, it is important to have listed at least a range or approximate value of the percentage composition for each element in the compound.
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Description:
The CHNS content is determined using the Pregl-Dumas method where your sample is prepared, introduced into the combustion chamber and burned at high temperature 925°F under pure oxygen. The resulting gas mixture and helium carrier gas pass through various reductive and catalytic zones to convert the gas mixture into CO2, H2O, N2, and SO2. The gasses are separated using gas chromatography and quantified with a thermal conductivity detector. Elemental analysis has been used for many decades in characterizing sample composition and purity. The machine can handle a wide variety of samples from solids, liquids, viscous samples, soils, and pharmaceutical agents.
Sample Purity:
The determination of the mass percentage of CHN elements in the sample is based upon the direct weight of the material sampled. Therefore, it is very important that samples are dry, free of foreign substances such as solvent, dust, rust, hair, aluminum foil, parafilm and paper filter fibers (the most common contaminant). The lab needs to know if and what metals, halides, or other interferences might be contained in the sample.
Potential problems:
In CHN mode, the accuracy is ±0.3%. Samples must be very pure and have the correct chemical structure to pass elemental analysis. If there are any solvents or moisture trapped in the sample, the accuracy of the results will be affected. Also, if the sample is not homogeneous, duplicate runs will not agree to within ±0.3%.
If a sample is extremely volatile, it may lose mass due to evaporation after it has been weighed out, even if it is crimp‐sealed in a special volatile sample pan. This can also cause the results to be inaccurate.
Some compounds are inherently difficult to combust completely. Incomplete combustion can also cause inaccurate results. In this case, the sample could be re‐run under different conditions, with an added oxygen boost, or with the addition of a chemical combustion aid such as vanadium pentoxide.
Other Requirements:
As the calibration of the instrument requires the theoretical percentage of each element, it is important to have listed at least a range or approximate value of the percentage composition for each element in the compound.