Metals Subgroup Agenda Metals subgroup membership 3 metals methods chosen for AOAC Pilot Project Nutritional Elements in Foods by ICP-AES – Improvement of AOAC OMA Method 984.27 As, Cd, Pb, Hg in Foods by ICP-MS – NMKL Interlaboratory Study Inorganic As in Rice by IC-ICP-MS NMKL and EU information on metals methods – Lars Voting members needed for community and metals experts for method reviews SLV document

5. SLV Document Introduction Definitions Performance criteria Should we provide in guidance document? Should we simply reference some sources? Performance characteristics Some are method development, some are validation – how do you feel about them being intermingled? Technical guidelines and approaches Representative analytes and representative species – do you agree with this approach?

Analytical range and linearity Matrix effects – 2 scenarios 6 standards injected over expected concentration range Matrix effects – 2 scenarios Blank matrix, no blank matrix, greater than 10% difference in the slopes? LOD/LOQ – 3 approaches Evaluation of background noise, y-intercept approach, spiking experiments How do we want to calculate? Method blank vs blank matrix? Reps, days? Method recovery – 4 scenarios Blk matrix with target ML – 0.5ML, 1ML, 2ML Blk matrix with no target ML – 3LOD, 10LOD, upper limit of range No blk matrix with target ML – 0.5ML, 1ML, 2ML – No blk matrix with no target ML – 0.5X, 1X, 2X (or higher) of characterized concentration in matrix Levels, reps, days?

Instrument repeatability Method repeatability Inject cal curves 5 times in random order in one run Method repeatability Prepare pools of materials equivalent levels used in recovery studies Reps, levels, days Intermediate precision Same experiment as method repeatability study with different analyst and different instrumentation (if possible) Measurement Uncertainty – use data gathered in validation to calculate Ruggedness – Youden’s factorial approach Example of SLV experimental design Other Calculations?