BACKGROUNDOrganic carbon and nitrogen stable isotopes (δ¹³C, δ¹⁵N) in marine sediments are used as effective indicators to trace the changes of air, temperature, precipitation and other parameters in different geological time. Elemental analysis-isotope ratio mass spectrometry is a reasonable and effective method to measure the composition of organic carbon and nitrogen stable isotopes in marine sediments. At present, many domestic laboratories use the method of element analyzer (EA) and stable isotope ratio mass spectrometer (IRMS) to analyze the stable isotopes of organic carbon and nitrogen. However, the comparison of analytical method and data stability between different laboratories is lacking. The analytical results lack effective traceability, and the process lacks standardization and unification.

OBJECTIVESTo develop a method for determining organic carbon and nitrogen stable isotopes in marine sediments.

METHODSThree newly developed national first-class standard materials (GBW04701, GBW04702, GBW04703) and two international standard materials (EMA-B2152, EMA-B2151) were sent to 10 domestic laboratories, in order to verify the stability, precision and accuracy of EA-IRMS online technology test method through the comparative measurement between laboratories.

RESULTSThe data of each collaborative laboratory was accurate and stable, and the method had good repeatability and reproducibility. The results showed that precisions of ¹³C and ¹⁵N were better than 0.10‰ and 0.14‰, respectively.

CONCLUSIONSThrough comparative study, it has been proved that EA-IRMS online technology is suitable for the determination of organic carbon and nitrogen stable isotopes in marine sediments. A suitable method for the determination of marine sediment samples has been preliminarily established.