Exeter Analytical has released a white paper stating the ways in which a CHN elemental analyser design affects the accuracy of samples.
For the purpose of the research, the analysers were run in real time lab environments. Vertical and horizontal combustion systems were compared for the study. In a horizontal furnace arrangement, the sample is introduced into the combustion tube through a quartz ladle. This ensures that all the residues of the sample are removed. However in a vertical furnace arrangement the new samples are combusted on residues of previous samples.
According to the white paper, this difference played a major role in the accuracy of the analytical data collected. The vertical furnace systems had the potential to provide inaccurate data. However the main purpose of the CHN analysis is to ensure that a standard testing procedure is adopted so that the accuracy and precision of the data is consistent across all sample types. It is very difficult for the analyzer to set up parameters differently for each sample.
External laboratories have also conducted these tests and their findings have also been published in the white paper which states the advantages of a horizontal furnace system over other systems in terms of the time lost due to recalibration and re runs of samples. When more number of demanding samples is tested, the performance of the instrument can also differ considerably. The horizontal furnace arrangement eliminates this issue and produces accurate results consistently.