Development of certified reference materials for the determination of cadmium and acrylamide in cocoa

Since 1 January 2019 a maximum content of 0.6 mg kg^-1 cadmium (Cd) in cocoa powder sold to the final consumer or as an ingredient in sweetened cocoa powder sold to the final consumer (drinking chocolate) is set by the Commission Regulation (EU) No. 488/2014. Monitoring compliance with the specified limit value requires analytical measuring methods and reference materials for quality control. However, suitable certified reference materials intended for quality assurance and quality control purposes are still lacking. Therefore, three cocoa reference materials (ERM®-BD513, ERM®-514 and ERM®-515) were developed according to the requirements of ISO 17034 and the recommendations of ISO Guide 35. The whole process of reference material development, including material preparation, assessment of homogeneity and stability, characterisation and value assignment is presented. The assignment of the certified mass fractions was based upon an interlaboratory comparison study involving 19 expert laboratories for Cd and 12 laboratories for acrylamide. The certified mass fractions and expanded uncertainties (k = 2) of the reference materials were (0.181 ± 0.009) mg kg^-1 Cd (ERM®-BD513), (0.541 ± 0.024) mg kg^-1 Cd (ERM®-BD514) and (0.690 ± 0.029) mg kg^-1 Cd (ERM®-BD515). Acrylamide contents are given for information.