Determination performance of ICP-MS heavy metals in food and feed test method through participation of proficiency testing programs

The inductively coupled plasma mass spectrometry (ICP-MS) method is applied to determine the content of heavy metals (Pb, Cd, As, Hg) in food and animal feed samples at the National Institute for Food Control due to its high accuracy and quick response time. These samples were digested in a microwave using a mixture of nitric acid and hydrogen peroxide, with the yttrium internal standard added initially to control the analysis. The efficiency of the method was evaluated to meet the requirements of AOAC with reasonable specificity, working standard curve for elements in the range from 0.4 to 20 µg/L, the relative standard deviation of repeatability RSDr < 3,55%, and the recoveries (R%) ranged from 92.2 to 103.1%. The method has been validated by participating in international proficiency testing programs in 2021 and 2022 with a value of |z-score| ≤ 2. Therefore, the results affirm the laboratory's competency meets the requirements for the validity of test results ISO/IEC 17025 requirements, reliability for customers and authorities.