Inductively Coupled Plasma Collision Cell Quadrupole Mass Spectrometric Determination of Extractible Arsenic, Cadmium, Chromium, Lead, Mercury, and Other Elements in Food Using Microwave-Assisted Digestion: Results from an FDA Interlaboratory Study.

An interlaboratory study was conducted to test U.S. Food and Drug Administration (FDA) Elemental Analysis Manual (EAM) Method 4.7, "Inductively Coupled Plasma-Mass Spectrometric Determination of Arsenic, Cadmium, Chromium, Lead, Mercury, and Other Elements in Food Using Microwave Assisted Digestion." The goal of the study was to demonstrate the performance of FDA EAM Method 4.7. Fourteen laboratories participated in the collaborative study, including nine Food Emergency Response Network state laboratories and five federal FDA laboratories. Laboratories tested 8 labeled standard reference materials and 12 blinded foods: mayonnaise, dark chocolate, sunflower seeds, hamburger with cheese, brown rice flour (blinded reference material included as a test food), infant formula, canned smoked oysters, sardines in tomato paste, swordfish, mineral water, cinnamon, and a multivitamin. The blinded test foods represented every sector of the AOAC food triangle. Participants measured the mass fraction of each element in each sample in triplicate. Horwitz Ratio (HorRat) values were better than 1.5 for all As, Cd, Cu, Hg, Mo, Ni, Pb, and Se measurements when at least eight laboratories reported results greater than LOQ. The HorRat values were better than 1.5 for all Mn and Zn measurements except for the multivitamin and for all Cr measurements except for sunflower seeds, in which the nonhomogeneity was identified. The average HorRat value of the blinded test foods was 0.66 for results greater than LOQ ( = 4206). The study showed that the method performed satisfactorily as a standard method for extractible elemental analysis of food. The method met or exceeded the performance expected.