Determination of Cu, Zn, Pb, and Cr in Marine Gas Hydrate-Bearing Mud by ICP-OES: Method Development and Validation Based on Matrix-Matched Soil Standards

Accurate determination of heavy metals in marine hydrate-associated muds is crucial for tracing methane seepage, yet it faces challenges from complex matrices. This study developed a matrix-matched microwave digestion ICP-OES method. By comparing XRF spectral profiles and statistical tests, the feasibility of using soil certified reference materials to simulate marine mud matrices was demonstrated, thereby optimizing digestion parameters (power/temperature) and ICP-OES spectral line selection. Method validation revealed detection limits of 0.0004 – 0.0105 mg/L for Cu, Zn, Pb, and Cr, with spike recoveries ranging from 95.5% – 103.7%. Accuracy was further verified using soil reference materials (GSS-4/5) and comparative t-tests with ICP-MS data. This efficient and reliable method provides a practical analytical tool for geochemical exploration of marine gas hydrates.