6. AOACSPIFANMethods-2018Awards

226

C ampos G iménez & M artin : J ournal of AOAC I nternational V ol . 100, N o . 1, 2017  143

Table 2. Results of statistical analysis on original set of data a SMPR 2012.012 requirements n b Avg., mg/100 g ≤5% ≤10% HorRat RSD r , % RSD R , %

Table 4. Results of statistical analysis of the additional set of data: average, RSD r , RSD R , and HorRat values

≤5% ≤10%

SMPR 2012.012 requirements Infant formula RTF (milk-based) b Adult nutritional powder (low-fat)

Avg., mg/100 g

Adult nutritional RTF (high-fat) c

21

17.6

4.2

11.3

1.5

n a 10

, % RSD R

, % HorRat

RSD r

12.0 10.7 13.2

1.7

SRM 1849a d Child formula powder

17 19

8.1 4.9

3.5 2.6

3.7 4.5

0.5 0.5

10

17.6

1.5

6.5

0.9

Adult nutritional powder (milk protein-based) Infant formula powder (soy-based) Infant formula RTF (milk-based) Adult nutritional powder (low-fat) Adult nutritional RTF (high-protein) Infant elemental powder Infant formula powder (partially

19

6.3

1.4

3.2

0.4

RTF) or can mislabeling (most likely the powder) took place during the first round seemed to be confirmed. One of the participants decided to analyze the four bottles received in duplicate. To mirror this experiment, the decision was made to also analyze the samples at the Nestlé Research Center using a different method (AOAC Official Method SM 985.33 ). Both sets of data (data not shown) confirmed that the variability observed in the RTF sample came from sample heterogeneity not the method. These data were presented to the ERP in March 2016 and subsequently accepted. The precision figures obtained during this collaborative study show that Method 2012.22 complies with the requirements set in the corresponding SMPR, and thus, that the method is fit for purpose for the analysis of vitamin C ( l -ascorbic acid) in infant formula and adult/pediatric nutritionals. Both HPLC (5) or UHPLC (6) conditions are of equivalent performance, provided that suitability conditions are respected, thereby allowing for method applicability in all laboratories. These data were submitted to the ERP for review at the Mid-Year AOAC Meeting annual meeting held in March 2016 in Gaithersburg, MD. The ERP determined that the presented data met the SMPR set by SPIFAN, and thus recommended the method be granted Final Action status. We especially thank Colleen Fehrenbach at Covance Laboratories (Madison, WI) for dispatching samples to the participants. We greatly thank the following participants and their associates for their valuable contributions to the study: Karen Schimpf and Linda Butler Thompson, Abbott Laboratories (Columbus, OH); Dalal Aoude-Werner and Julie Dalmas-Le Grandois, Aérial (Illkirch, France); Jeanette Wong and Joanne Chia, ALS Global (Singapore); Isabelle Malaviole, Laboratoire Aquanal (Pessac, France); Maggie Mapar, Tiffany Nguyen, and Michael Hoard, Arizona Nutritional Supplements (Chandler, AZ); George Joseph, Asure Quality (Auckland, New Zealand); Lifu Ma, Certified Laboratories (Plainview, NY); Bolong Wu, Chinese Academy of Inspection and Quarantine (Beijing, People’s Republic of China); Tom Rogers and John Austad, Covance Laboratories (Madison, WI); Bente Marianne Jensen, Ina Pedersen, and Sabine Meng Jensen, Eurofins Steins Laboratorium A/S (Vejen, Denmark); Yinghui Zhang and Wenjuan Jobgen, Eurofins Scientific, Inc. (Des Moines, IA); a  n represents the number of laboratories in the evaluation. No outliers were removed. b RTF=Ready-to-feed. Conclusions Acknowledgments

17

10.3

1.6

6.0

0.8

25.6 e

30.6 e

3.3 e

19

3.5

31.8 e

33.0 e

4.2 e

21

11.0

18

19.7

1.7

9.3

1.3

21

34.0

7.3

11.4

1.7

22

19.5

2.4

8.0

1.1

hydrolyzed, soy-based)

the SMPR. Repeatability decreased from 31.8% in the part 2 to 1.5%, whereas reproducibility decreased from 33.0 to 6.5%; both values well below requirements. For infant formula RTF (milk-based), despite improved precision numbers (repeatability went from 25.6 to 10.7%, whereas reproducibility went from 30.6 to 13.2%), these values remained outside of the SMPR. The hypothesis that either sample spoilage (presumably of the , and HorRat values after removal of outliers. b n represents the number of laboratories considered in the evaluation (after removal of outliers). Twenty-two laboratories reported data. c  RTF=Ready-to-feed. d  SRM=Standard Reference Material. e  Results suspected to be related to sample integrity. See Table 4 for the final reproducibility results on these two matrixes. a  Average, RSD r , RSD R

Table 3. Full set of additional data on matrixes suspected to be spoiled (liquid) or mislabeled (powder) in the original testing a

Lab No.

Infant formula RTF (milk-based) b

Adult nutritional powder (low-fat)

1 2 3 4 5 6 7 8 9

17.5 20.0 18.2 17.7 17.5 18.0 16.0 16.4 17.1 17.8

18.0 20.1 18.0 17.6 17.3 17.7 15.3 17.0 17.5 17.9

13.1 12.9 11.7 12.5 13.2 12.7 13.8 11.5 10.7

13.0 12.2 14.1 10.9 12.0 15.0

9.8

10.5 11.0

10 9.8 a  All results are in mg/100 g of reconstituted powder (25 g+200 g water) or are as-is for RTF. b  RTF=Ready-to-feed. 9.0