Ivanova V.Chakarov K.2026-01-202026-01-202026-01-202026-01-202025-11-202267-12422555-040310.1051/e3sconf/202565905002SCOPUS_ID:105023447760https://rlib.uctm.edu/handle/123456789/1936This study presents a combined analytical approach for determining total mercury (THg) and mercury species (CH3Hg+ and Hg2+) in marine sediments. THg was measured using AMA-254, while speciation analysis was performed by GC-ICP-HRMS with double isotope dilution calibration approach. In the sediment sample, CH3Hg+ was 0.00054 ± 0.00011 mg kg-1 and Hg2+ was 0.118 ± 0.030 mg kg-1. The sum of mercury species closely matched THg values obtained by AMA, confirming the method's reliability with 85% recovery. The low detection limits enabled accurate quantification of mercury, even at trace levels. Combining both techniques allowed a clearer distinction between the main mercury species and improved understanding of their distribution in the sediment. This approach is reliable for accurate mercury determination and the results can contribute useful information for future environmental assessments and monitoring efforts.enConference Paper