Reference measurements for cadmium, copper, mercury, lead, zinc and methyl mercury mass fractions in scallop sample by isotope dilution inductively coupled plasma mass spectrometry

Abstract

A marine certified reference material (CRM), IAEA 452, prepared with scallop (Pecten maximus) sample was recently produced by the Environment Laboratories of the International Atomic Energy Agency (IAEA) and certified for trace elements and methyl mercury (MeHg) mass fractions.The present work describes the certification of Cd, Cu Hg, Pb, Zn and MeHg in scallop (P. maximus) sample. The reference values for the Cd, Cu Hg, Pb, Zn and MeHg mass fractions were obtained with isotope dilution inductively coupled plasma-mass spectrometry (ID ICP-MS) applied as a primary method of measurement.A procedure based on complete digestion of the samples and ID ICP-MS was developed with the objective of achieving expanded uncertainty of the final results of 1.5–4.56%. A systematic assessment of all factors influencing the measurement results as sample-spike isotopic equilibrium, homogeneity study, factors affecting blend ratio measurements, efficiency of the sample digestion procedure, possible interferences, matrix effects etc. was done throughout the present study. Modelling of the entire measurement process and the use of reference materials relates obtained values for Cd, Cu Hg, Pb, Zn and MeHg to SI units of the mole or the kilogram.The agreement between obtained results and those derived from the worldwide Inter-laboratory Comparison between 146 laboratories, organised by IAEA on the same sample matrix (less than 1% difference), further validated the methods developed at Environment Laboratories of IAEA.