Exeter Analytical has published an optimised technique for the direct determination of organic carbon and nitrogen in marine sediments.
The filter-based technique, using an Exeter Analytical Model 440 CHN elemental analyser, provides the rapid routine analysis of marine sediments.
Results are expressed in micrograms of carbon and nitrogen detected, simplifying the calculation process.
Analytical sensitivity is less than 1mg.
The Exeter Analytical Model 440 is a static combustion system, with a horizontal furnace design that simplifies the removal of filter and sample ash between each sediment analysis.
Consequently, one combustion tube will analyse more than 1,000 sediment samples without the need for removal and cleaning.
In addition, the Model 440 provides the capacity to process filters up to 47mm in diameter in one analytical cycle.
By comparison, according to the company, other elemental analysers, employing vertical furnace designs, need cleaning after as little as 20 samples and larger filters have to be sub-sampled several times and then corrective calculations made to enable analysis.
Effectively eliminating troublesome residue build-up, the gas flow characteristics of the Model 440 analyser are claimed to be better than other elemental analysers, thereby providing longer-term calibration stability as well as enhanced accuracy and precision for measured sample data.
As the Exeter Analytical Model 440 provides complete control over combustion parameters, it is able to reproducibly achieve 100 per cent combustion with a wide range of sediment samples.
For sediment samples with low levels of nitrogen in the 0.1 to 0.2 per cent range, proprietary nitrogen analysis software enables accurate measurement at these levels with a high degree of accuracy.
