ε-TaN as a reference material for the determination of high nitrogen contents

Today it is possible to replace the costly Kjeldahl method by the commonly used Carrier Gas Hot Extraction (CGHE) method for the determination of nitrogen contents of up to 50 wt%, because the accuracy of this method was improved up to a 0.2% relative standard deviation. The remaining problem is the availability of defined and stable standards for N analyses by Carrier Gas Hot Extraction. In this study, we compared different certified standards with epsilon-TaN, which is a so-called "line compound" with a defined nitrogen content. A nitrogen content of almost theoretical composition was found for epsilon-TaN using compact samples analysed by CGHE and combustion-GC (Dumas-GC) analysis while the nitrogen content decreased in powdered samples. epsilon-TaN is a well-suited and stable potential reference material especially if the gas analyser is capable of analysing and decomposing compact pieces of this material.