Factors affecting CHN micro-analytical performance

Exeter Analytical have released a new technical paper that provides a useful introduction to elemental (CHN) microanalysis and discusses how instrument design affects performance (accuracy, precision), ease of use and handling of demanding sample types.

Increasingly today analysts are looking for improved data accuracy, precision and long-term stability when determining CHN content to comply with more stringent quality practises. Of the 3 types of CHN elemental analyser (dynamic, hybrid and static measurement systems), all can be demonstrated to produce accurate and precise data. The new technical paper examines the consequences of these design differences when the analysers are run in real laboratory environments.

Data is provided showing the impact of horizontal versus vertical combustion systems. In a horizontal furnace arrangement the sample is introduced into the combustion tube on a quartz ladle, which critically enables the removal of all sample residues after combustion. In a vertical furnace arrangement the samples are combusted on top of previously combusted samples. This difference is a major factor contributing to the advantages of a static system with a horizontal furnace over both the dynamic and hybrid designs. This build up of sample residue in the combustion zone of vertical furnace systems is shown to considerably increase the potential for poor analytical data.

The most important criteria for CHN analysis in the majority of analytical laboratories are for optimal accuracy and precision across a wide range of sample types. With constant pressure to increase laboratory productivity an analyst does not want to set up their analyser with different operational parameters for every different sample type they come across. Test data from an independent multi-laboratory study is included demonstrating not only the superior accuracy and precision routinely achievable, but also how the inherently longer term stability with a horizontal furnace design markedly decreases time lost due to the need for recalibrations and sample re-runs.
Considerable variance in instrument performance can also be seen with more demanding samples. The advantages of a horizontal furnace design CHN microanalyser is illustrated with applications including time-dependent combustible samples and volatile liquids.

The report concludes that using a horizontal furnace design CHN microanalyser, such as the Exeter Analytical Model 440, allows analysts to routinely and simply produce accurate and precise data on wide ranging sample types without system re-optimisation, saving precious time and reducing running costs.

For a copy of the technical paper 'How instrument design affects CHN micro-analytical performance' and further information on the Model 440 please contact Exeter Analytical.