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Part 2: Multi-Laboratory Test Participation
MLT Samples
Receipt
All qualified laboratories were provided feedback to go forward with the MLT.
The “SPIFAN and IDF/ISO MLT Samples Receipt Form” (Annex E) was to be
filled and sent back to the Study Director.
Analysis
The laboratories were asked to analyze all the samples (single determination
from each reconstituted sample) on two days (25 samples per day). Each
sample was assigned to either day 1 or day 2 (see Annex A).
The samples were analyzed singly and individual values reported. It was of
critical importance to analyze the samples on their assigned day. It was also
highlighted to the participants that this was a study of the method, not the
laboratory; the method set up in the first part of the study should be closely
followed. Any deviation was to be recorded and reported.
All powdered samples were required to be analyzed on a reconstituted basis,
using 25 grams of material and 200 grams of water, as stated in the method,
with the exception of MLT Sample 26 (KGSZ273) and MLT Sample 29
(LTCT316). These two samples were to be reconstituted by dissolving
10 grams of powder in 90 grams of water (see Annex A for reconstitution
rates).
Special notes on IDF samples:
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Method matrix addition samples – See note in method section.
1) For processed cheese ISO 5943 to be used: Weigh 2-5 g of test sample
into the vessel (for processed cheese 2.5 g). Add 30 ml of water at
about 55°C. Suspend the test portion using the blender. Rinse the
blender with approximately 10 ml of (demi) water, collecting the
rinsings in the vessel. Add 2 ml to 3 ml of the nitric acid (4 mol/l). titrate
(same method AOAC 2016.03 can be used)
2) For salted butter ISO 15648 to be used: Weigh 2-4 g of test sample
into the vessel (for salted butter 2.5 g). Add 100 ml of boiling water and
heat to boiling to dissolve the test portion. Cool the obtained
suspension to below 55°C. Titrate (same method AOAC 2016.03 can
be used). In the case of a difficult titration, the addition of 2 ml to 3 ml
of the nitric acid (4 mol/l) to the contents of the vessel before titration
is allowed. (By testing this in the collaborative study (in ANNEX of ISO
15648) it was shown that the same level of precision was attained.
If there were any questions, the laboratories were instructed to directly address
them to the Study Director.
Timeline
The results on the MLT samples were to be provided within 6 weeks from
sample reception.
2016.03 (APRIL 2017) - MTE-01/03
MLT REPORT
FOR ERP USE ONLY
DO NOT DISTRIBUTE