Development of Nitrogen and Organic Carbon Reference Materials for China Offshore Marine Sediments

The study of marine sediments in China has developed rapidly in recent years, but the standard materials with certified values for nitrogen organic and carbon are relatively lacking. In light of this the standard materials for total nitrogen (TN), total carbon (TC) and total organic carbon (TOC) have been prepared and are reported in this paper. The samples were collected from the surface sediment for the ‘China Offshore Marine Integrated Investigation and Evaluation Project’. After being frozen and dried, the samples were ground into 74 μm. The contents of TN and TC were measured by using an elemental analyzer and oxidation of pyrolysis Gas Chromatography. The content of TOC was measured by using an elemental analyzer and the oxidative pyrolysis potential method. A series of 16 sediment reference materials with certified values of TN, TC and TOC content has been developed. In the uniformity test, the measured values are less than the critical value of F, relative deviation is small, indicating better uniformity. Good stability was verified by repeating the analysis multiple times within the past two years, without any changes. The 16 offshore sediment reference materials were tested in three laboratories, following the ISO guide 35 and national level standard materials specifications. The series of standard materials provided certified values of TN, TC and TOC with uncertainties. The samples are from different areas and different sediment types. The results show that different sea sediment types of standard materials are essential and this work contributes to existing marine sediment reference materials.