Abstract:Its often seen the reports of excessive cadmium (Cd) pollution in laver products, so the accurate and efficient determination of Cd content in laver is of great significance. A method of isotope dilution-inductively coupled plasma mass spectrometry (ID-ICP-MS) with microwave digestion was established for the quantitative analysis of Cd in laver. The effects of three digestion systems (includes HNO3, HNO3＋H2O2 and HNO3＋HF) on the determination results were discussed. The addition time of HF and amount of HF in the HNO3＋HF system were further optimized. And the method was verified using Certified Reference Material (GBW08521). The results showed that the HNO3＋HF system had the best digestion effect on laver samples, and HF should be added before digestion. What’s more, for 0.2 g amount of laver samples, the addition of 0.5 mL HF can completely digest them. Compared with conventional ICP-MS method, the ID-ICP-MS method can effectively eliminate the influence of matrix effect. And the measurement accuracy and precision of the method are good. The determination of Cd content in GBW08521 reference material by ID-ICP-MS method was 5.3 mg/kg, and the expended uncertainty was 0.1 mg/kg with the coverage factor k=2. Compared with the standard value, the normalized deviation |En| value was 0.25 (smaller than 1), indicating that the method is accurate and reliable. In addition, in the spiked recovery experiment, the Cd spiked recovery rates of different samples were all between 90% and 110%, indicating good recovery effects. The analysis results of actual samples of laver showed that the combination of HNO3＋HF digestion system and ID-ICP-MS method is more universal than the national standard method mentioned in GB 5009.268-2016. This method can be used as the determination method of Cd content in reference materials, and can be applied to high-precision analysis of Cd content in complex matrices such as laver.