Determination of Minerals and Trace Elements in Infant Formula and Adult/Pediatric Nutritional Formula by Inductively Coupled Plasma/Mass Spectrometry A Performance Evaluation: Single-Laboratory Validation, First Action 2015.06.

Abstract

A method for determination of 12 minerals and trace elements (Na, Mg, P, K, Ca, Cr, Mn, Fe, Cu, Zn, Se, and Mo) in infant formula and adult/ pediatric nutritional formula was developed and evaluated in a single-laboratory validation. Some additional reproducibility data were obtained from a small interlaboratory study. The method involves microwave digestion of the sample followed by inductively coupled plasma/MS and uses Ge and Te as internal standards. The method is an extension of Official Method(SM) 2011.19 and was compared to AOAC Standard Method Performance Requirements (SMPRs®) 2011.009 and 2014.004 developed by the AOAC Stakeholder Panel on Infant Formula and Adult Nutritionals (SPIFAN). Repeatability precision for the 12 elements in 11 SPIFAN matrixes and National Institute of Standards and Technology Standard Reference Material (SRM) 1849a was <5%, meeting the SMPR criterion for repeatability. Intermediate reproducibility (8 days, two analysts, two instruments) in the 11 SPIFAN matrixes was <5% for nine (Na, Mg, P, K, Mn, Fe, Cu, Zn, Se) of the 12 elements in all 11 matrixes. The mean reproducibility across 6-7 laboratories and seven SPIFAN matrixes ranged from 2.5% for Cu to 7.1% for P. Recovery from spiked matrixes varied from 90.1 to 109%, and accuracy of determination using SRM 1849a ranged from 96.2 to 107.7%, meeting the requirement of 90-110% recovery/accuracy.