Validation of Total Combustion Methods to Determine Low Level C/S/N/O in Limited Size Samples

Los Alamos National Laboratory’s Actinide Analytical Chemistry group recently replaced its custom built conventional manomeric system for carbon analysis due to age and increasing maintenance difficulties with an Eltra CS800. This will allow simultaneous analysis of both carbon and sulfur. In addition, it has replaced a time consuming method for nitrogen based on the Kjeldahl distillation method followed by an analysis with a Dionex ion chromatography system with a LECO TC600 system which analyzes nitrogen and oxygen simultaneously. Both of the new instruments function on total combustion of the sample and require less than 5 minutes analysis time per sample. Infrared detection is used for C/S/O while a thermal conductivity detector for N is required. Standard ASTM and ISO methods for methods using the new systems for the analysis of nuclear materials typically require 1 g of material; however, this is most often not possible due to ALARA concerns as well as limited amounts of material for many types of samples. This report will focus on the efforts at reducing the required sample size by an order of magnitude while maintaining a low detection limit of 20 ppm or better.