AOACSPIFANMethods-2017Awards

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1702 Pacquette & Thompson : J ournal of AOAC I nternational V ol. 98, N o. 6, 2015

INFANT FORMULA AND ADULT NUTRITIONALS

Determination of Chromium, Selenium, and Molybdenum in Infant Formula and Adult Nutritional Products by Inductively Coupled Plasma/Mass Spectrometry: Collaborative Study, Final Action 2011.19

Lawrence H. Pacquette and Joseph J. Thompson 1 Abbott Nutrition, 3300 Stelzer Rd, Columbus, OH 43219

Collaborators: M. Farrow, M. Feller, Y. Fenpeng, M. Gray, I. Malaviole, A. Mittal, D. Mould, F. Xiang, S. Yadlapalli, S. Zhang, Y. Zhang

(Cr) and molybdenum (Mo; 1, 2). Together these ultratrace elements represent some of the most difficult analyses for any laboratory testing against the relatively narrow specification ranges mandated by many regulatory bodies for these added nutrients in infant and pediatric formulas. Existing official methods that have been specifically validated for Cr, Mo, and Se in infant and pediatric nutritional products were virtually nonexistent until theAOAC Stakeholder Panel on Infant Formula and Adult Nutritionals (SPIFAN) issued a Call for Methods in 2011 and a suitable method was put forward that was already being used in the authors’ laboratory (3). This method appeared to have the requisite precision, accuracy, and ruggedness for ultratrace element analysis based upon successful completion of an internal single-laboratory validation (SLV). The SPIFAN Working Group had formulated a set of Standard Method Performance Requirements (SMPRs ® ) that captured the needs of the formula manufacturers for a suitable global dispute resolution method for ultratrace element analysis. SMPRs were approved by stakeholders (4), and the AOAC Expert Review Panel (ERP) on SPIFAN Nutrient Methods approved only this method as First Action in 2011 (AOAC 2011.19 ) because it appeared to meet the SMPRs on that manufacturer’s own products. However, the ERP requested the SLV be repeated with the specific set of SPIFAN matrixes developed to be representative of most of the other manufacturers’ products. After examining the second set of SLV data, the ERP voted that the method proceed to a multilaboratory testing (MLT) of reproducibility. These latter SLV data have not been published before and are captured in this report with the subsequent MLT collaborative data usingAOACmethod 2011.19 . Multilaboratory Collaborative Study Initially 16 laboratories expressed interest in participating in the AOAC 2011.19 ultratrace element collaborative study, but only nine laboratories were able to complete the study because of lack of time or resources, or they could not import the samples in due time. The nine participating laboratories were located in four different countries (China, United States, India, and France) and were equipped with seven different models of inductively coupled plasma (ICP)/MS instruments, namely the PerkinElmer (Shelton, CT) ELAN DRC-e, ELAN DRC II, and NexION 300D; the Agilent (Santa Clara, CA) 7700x and 7500cx (the latter used only during the authors’ SLV); and the Thermo Scientific (Waltham, MA) iCAP Q and X Series 2. All these instruments

Received on May 27, 2015. Accepted by SG June 15, 2015. The method was approved by the AOAC Official Methods Board as Final Action. See “Standards News,” (2014) Inside Laboratory Management , November/December issue. The AOAC Stakeholder Panel on Infant Formula and Adult Nutritionals (SPIFAN) invites method users to provide feedback on the Final Action methods. Feedback from method users will help verify that the methods are fit for purpose and are critical to gaining global recognition and acceptance of the methods. Comments can be sent directly to the corresponding author. 1 Corresponding author’s e-mail: joseph.thompson@abbott.com DOI: 10.5740/jaoacint.15-139 rejected in its entirety. The method demonstrated acceptable repeatability and reproducibility and met the AOAC Stakeholder Panel on Infant Formula and Adult Nutritionals (SPIFAN) Standard Method Performance Requirements (SMPRs ® ) for almost all of the matrixes analyzed. The Cr, Mo, and Se SPIFAN requirement for repeatability was ≤5% RSD. The SMPR called for a reproducibility of ≤15% RSD for products with ultratrace element concentrations above the targeted LOQ of 20 µg/kg Cr/Mo and 10 µg/kg Se (as ready-to-feed). During this collaborative study, RSD r ranged from 1.0 to 7.0% and RSD R ranged from 2.5 to 13.4% across all three ultratrace elements. M ost infant formulas are fortified with the essential trace element selenium (Se); many pediatric and adult nutritional products are also fortified with chromium AOAC First Action Method 2011.19: Chromium, Selenium, and Molybdenum in Infant Formula and Adult Nutritional Products, was collaboratively studied. This method uses microwave digestion of samples with nitric acid, hydrogen peroxide, and internal standard followed by simultaneous detection of the elements by an inductively coupled plasma (ICP)/MS instrument equipped with a collision/ reaction cell. During this collaborative study, nine laboratories from four different countries, using seven different models of ICP/MS instruments, analyzed blind duplicates of seven infant, pediatric, and adult nutritional formulas. One laboratory’s set of data was