Rapid direct determination of organic carbon and nitrogen in carbonate-bearing sediments with a Yanaco MT-5 CHN analyzer

A rapid technique is presented for measuring organic C and N in carbonate-bearing sediments. Organic C and N were determined with a Yanaco MT-5 CHN analyzer after removing carbonate by acidification of samples in ceramic sample boats with HCl vapor. This procedure eliminates loss of acid-soluble organic matter during carbonate dissolution. The accuracy of this new technique and two earlier methods of determining organic C and N concentrations was verified with standard chemicals and carbonate-bearing sediments (> 80 wt% CaCO3). With the new technique there was no contamination or loss of organic C and N. The method is suitable for acidifying sediments with a wide range of carbonate content.