6. AOACSPIFANMethods-2018Awards

79

1720 Thompson et al.: J ournal of AOAC I nternational V ol. 98, N o. 6, 2015 7500cx from the SLV, a few Agilent 7700x, a PerkinElmer ELAN DRC-e, and a Thermo X Series 2. On the other hand, it is of interest to note the excellent RSDs for Mn and Cu across these laboratories—likely due to the excellent sensitivity of the ICP/MS for these elements and the effectiveness of the CRCs in removing background interferences at somewhat higher mass.

models of ICP/MS instruments. The data from the SLV and MLT studies were consistent with each other. Additional linearity work, spiking at low-levels, increasing sample size, and/or additional low level standards would be needed to prove accuracy at the lowest levels for Fe, Cu, and Mn.

Acknowledgments

The accuracy of the present method can be further attested to by comparison to an independent method, the commonly used ICP-AES, also with microwave digestion. A full SLV was performed on the SPIFAN matrix set in the authors’ laboratory using the same microwave oven (CEM MARS 5 with MARSXpress™ vessels) and two PerkinElmer Optima ICP instruments. The mean 6-day ICP-AES results were compared to the mean values from the ICP/MS MLT (similar to those means in Table 4). The results are shown in Table 8. Again, we must disregard the numbers for the Adult RTFs because the ICP-AES data were acquired several months ahead of the MLT study, and these products had probably physically deteriorated. The remaining powder products show remarkable agreement between the two spectroscopies. In general, MS data are higher than those produced by emission, but seldom is there more than 6% difference. Conclusions The method, as is, meets all SMPRs except for the LOQ of Fe, Mn, and Cu. There was also substantial evidence presented to support the accuracy and reproducibility of this method through comparison to an independent method and through analyses completed at independent laboratories with different

We thank Andre Szabo for participating as the second analyst in this SLV. Also, we thank the participants of the OMA 2011.19 collaborative study that contributed nine- element data for this report: Fan Xiang, Sudhakar Yadlapalli, Isabelle Malaviole, Ashutosh Mittal, Michael Gray, Diana Mould, and Michael Farrow.

References

(1) Official Methods of Analysis (2011) AOAC INTERNATIONAL, Rockville, MD, SMPR 2011.009. www.eoma.aoac.org (2) Official Methods of Analysis (2014) AOAC INTERNATIONAL, Rockville, MD, SMPR 2014.004. www.eoma.aoac.org (3) Official Methods of Analysis (2011) AOAC INTERNATIONAL, Rockville, MD, Official Method 2011.19 . www.eoma.aoac.org (4) Pacquette, L., Szabo, A., & Thompson, J. (2011) J. AOAC Int . 94 , 1240–1252 (5) Official Methods of Analysis (2012) AOAC INTERNATIONAL, Rockville, MD, Appendix L. www.eoma.aoac.org (6) Thompson, J., Pacquette, L., & Brunelle, S. (2015) J. AOAC Int. 98 , in press