AOAC SPIFAN ERP Meeting Book (3-16-16)

Additional data on Multi-Laboratory Validation – Vitamin C method AOAC First

Action 2012.22 / F. Martin, NRC/AS

23.Nov.2015

CONFIDENTIAL

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R E S U L T S A N D C O N C L U S I O N

Participation to MLT

From the 12 laboratories that initially initially accepted to participate, two of them did not receive

the MLT samples due to customs restrictions. The remaining 10 laboratories reported valid data.

Results

Summarized results of the additional MLT set of samples can be found in the table below. Full set of

data is given in Annex B

Requirements (SMPR 2012.012)

≤ 5 % ≤ 10 %

Sample

Mean

(mg/100 g RTF)

RSD

(%)

RSD

(%)

HorRat

Adult Nutritional Powder Low Fat

17.6

1.5

6.5

0.88

Infant Formula RTF Milk Based

12.0

10.7

13.2

1.70

n = number of laboratories (after outliers removal)

RSD

: relative standard deviation of repeatability

RSD

: relative standard deviation of reproducibility

The results for the Adult Nutritional Powder Low Fat product are now well within the SMPR

requirements. The repeatability went down from 31.8 % for the first round to 1.5 % in the present

study, whereas the reproducibility went down from 33.0 % to 6.5 %. The hypothesis that during the

first round the high precision data came from either homogeneity of the sample itself, storage

spoilage or can mislabelling seems to be confirmed.

Regarding the Infant Formula RTF Milk Based, even if the precision numbers improved (repeatability

down from 25.6 % to 10.7 %, reproducibility from 30.6 % to 13.2 %), they remained slightly outside

of the requirements.

One of the participant laboratories analysed duplicate samples the four bottles they received. The

data are presented in the table below:

2012.22/VitC-03 (February 2016) - MLT

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