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

Results and Discussion The specificity and accuracy of the method was established during the single laboratory study which was published in the March 2017 issue of the Journal of AOAC International [5] . Accuracy was further determined by the analysis of whey protein spiked in skim milk powder at three different levels by 5 Chinese labs using two different CE instrument manufacturers (Table 2016.15D). These results confirmed method accuracy since the spike-recovery rates satisfy the AOAC SMPR [4] for whey protein analysis. As mentioned, the initial phase of the MLT involved the analysis of practice samples by the participating laboratories. The two practice samples were manufactured by Wyeth Suzhou and contained about 40% and 60% whey proteins respectively based on the formulation and the characterization of the ingredients by this method. These two samples were also tested in a small scale method validation in 4 Chinese government laboratories with duplicate analyses over six days. The raw data (%whey) and associated statistics (per lab, global) including standard deviation of repeatability and between-laboratory reproducibility; limits of repeatability (r) and reproducibility (R), Horwitz Ratio (HorRat), and Cochran’s C value from 4 different laboratories for the two practice samples are presented in Table 2016.15E. A total of 20 laboratories agreed to participate to this study: 19 laboratories submitted data for evaluation, one laboratory failed to correctly integrate one pair of sample. Only 1 laboratory did not report any data. Among the 19 laboratories that provided data, 3 laboratories joined the study during the MLT data collection phase, 1 laboratory did not receive the practice samples on time because of shipping delays to international locations (these 4 laboratories were excused for not supplying the results for the two practice samples before the official sample testing), 3 laboratories (who received samples late) analyzed the practice samples at the same time as the MLT testing samples, and 1 laboratory analyzed the practice samples in singlet instead of duplicate as requested. The statistical analysis results of the practice samples from the 15 laboratories who submitted results are listed in Table 2016.15F. The results show that all 15 laboratories passed the practice sample testing (the criteria for SX1 and SX2 were set to 41.5±3.9 and 60.8±3.4 based on the reproducibility limits shown in table 2016.15E). Practice sample 2 (SX2) was designated as the Quality Control (QC) sample and was required to be included in each analysis run during the MLT study. The analytical run was first evaluated based on the value of the result of the QC sample. The analysis run was accepted only when the QC value fell within the acceptable range (60.8±3.4). Upon completion of all analyses, each participating laboratory reported measured results with corresponding electropherograms for each sample (30 analyses total). The results received from participants were tabulated and are summarized in Table 2016.15G.