AOAC SPIFAN WPC ERP-Final Action Review (Nov. 2017)

2016.15 (Nov. 2017) - WPC-31 MLT-Final Action Review

FOR ERP USE ONLY DO NOT DISTRIBUTE

Quantification of Whey Protein Content in Milk-Based Infant Formula Powders by Sodium Dodecyl Sulfate – Capillary Gel Electrophoresis (SDS-CGE): Multi- Laboratory Testing Study, Final Action 2016.15

Ping Feng 1 , Christophe Fuerer 2 and Adrienne McMahon 3

1 Wyeth Nutrition, 30F, CITIC Square, 1168 Nanjing Rd. (W), Shanghai 200041, PR. China 2 Nestlé Research Centre, Vers-Chez-Les-Blanc, PO Box 44, 1000 Lausanne 26, Switzerland 3 Wyeth Nutrition Ireland, Askeaton, Co. Limerick, Ireland Collaborators: Xiaojing Ding; Guoquan Wang and Xuefei Leng; Li Li; Hongxu Chen and Tie Gao; Chunmei Zhang and Kai Huang; Jie Zhou; Xinxiang Zhang and Yue Yu; Liqing Wu and Kangle Zheng; Yunxia Wang; Wei Chen; Yongtan Yang and Youyou Yang; Songlin Yan and Jiazheng Pan; VickyManti and KristyArendse; ShaoqingWang; Allen Chanady and Steve Questa; Rosemarie Jenni; Mei-an Sung; Hao Zhang; Xin Wang. 1 Corresponding author’s e-mail: ping.feng@wyethnutrition.com Abstract A Multi-Laboratory Testing study was conducted on AOAC Official Method SM First Action 2016.15: Quantification of Whey Protein Content in Infant Formula Powders by Sodium Dodecyl Sulfate-Capillary Gel Electrophoresis (SDS-CGE). Nineteen laboratories participated in the analysis of duplicate samples of 15 formula powder products for infants and young children. Electrophoregrams (eGrams) were recorded at UV220nm and integrated. The normalized peak areas of whey and casein proteins were summed separately to calculate total whey protein content. Apart from one sample (NIST SRM 1849a), relative standard deviation of repeatability (RSD r ) and reproducibility (RSD R ) ranged from 0.83 to 2.11% and from 2.18 to 4.22%, respectively, and Horwitz ratios ranged from 1.02 to 1.85, meeting the precision limits specified in the whey protein Standard Method Performance Requirements [4] and in the guidelines recommended for the Horwitz ratio [6] . In these samples, the measured whey protein content was between 98% and 108% of the declared value. NIST SRM 1849a showed atypical results, with elevated RSD r (3.51%), RSD R (5.94%), Horwitz ratio (2.62), and recovery (134%). There is no clear reason for this. The %Whey protein value for NIST is calculated from the formulation and is not a reference or certified value. Multiple instrument models and makes as well as capillary sources were used in this collaborative study, demonstrating the versatility of the method. Good performance and ease of implementation for routine use in a QC environment indicate that this method is fit-for-purpose for the quantification of whey protein content in milk-based formula powder products for infants and young children.