Determination of Rare Earth Elements in the Marine Sediments by Inductively Coupled Plasma-Mass Spectrometry with High-pressure Closed Digestion

Using a HF-HNO₃ system with high-pressure closed digestion, a method to determine concentrations of fifteen rare earth elements (REEs) in marine sediments was studied by Inductively Coupled Plasma-Mass Spectrometry (ICP-MS). Experimental conditions such as mass spectrum interferences, digestion methods and acid systems have been investigated. Compared to electric heating plate digestion and microwave digestion, high-pressure closed digestion has the advantages of using less acid, achieving complete digestion and causing less damage to the digestion process. The correction equation effectively calibrated polyatomic ions interferences formed by Ba and light rare earth elements. The marine sediment samples were dissolved completely by HF-HNO₃ system, and the relative error (RE) was less than 5%. The method detection limits were 3-15 ng/g. The proposed method was validated by the marine sediment reference materials GBW 07309, GBW 07311 and GBW 07313. The results were consistent with certified values, and the relative standard deviation (RSD) and relative error were both less than 5%. The determination precision (RSD, n=6) of the Yangtze River estuary sediment samples was less than 5%, and the recoveries were 95.8%-104%. This method has a low detection limit with high precision and accuracy, all of which meet the requirements to analyze a large number of marine sediment samples.