Food Industry Summit organised by Food Industry Asia (www.foodindustry.asia) : 06 September 2012

2. CASE STUDY 3:
Contaminants &
Analytical Methods
- Ruowei Strange
- Lionel Buratti

3. Contaminant Limits & Analytical
Methods
PART TWO
Lionel Buratti

4. ANALYTICAL METHODS
…AS HIDDEN TBT
A further complication is that in some cases there are
no internationally accepted ways of testing for certain
contaminants.
Heavy metals can be analysed using several
techniques with different limits of detection (LoD).
For example, most
laboratories across ASEAN
use the Flame AAS method
for lead detection, although
the more modern ICP-MS technology enables more
accurate and automated analysis.
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5. ANALYTICAL METHODS
…AS HIDDEN TBT
There is little consensus across ASEAN on which
methods to use, and companies face disputes within
the sector itself (supplier-customer) and with regulatory
bodies due to discrepancies in analytical results.
Manufacturers, suppliers and
regulators can be confronted
with different analytical results
obtained from different analytical
techniques and equipment in
different laboratories and countries.
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6. ANALYTICAL METHODS
…AS HIDDEN TBT
Scientifically, this arises from the complexity
of sample matrixes and the variation in
analytical methods - measurement
uncertainty (MU)- stating that no measurement is exact.
When a quantity is measured, the outcome depends on
the measuring system, the measurement procedure, the
skill of the operator, the environment, and other effects.
Usually in labs, we use the following criterias:
• repeatability (r), i.e. Same analyst doing the test
twice
• reproducibility (R), i.e. Two analysts doing the test
with the same method on different days / location
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7. ANALYTICAL METHODS
…AS HIDDEN TBT
Disputes are most notable when
analytical results are near to
specification or regulatory limits.
For example, it is not easy to ascertain the
accurate (True value) of lead results at 1.0 mg/kg
by AAS and ICP-MS
with precision as follows:
By AAS : r <27% R <50%
By ICP-MS : r <13% R <32%
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8. R<50%
r<27% AAS
0 mg/kg 1.0 mg/kg
0.8 mg/kg
0.67 mg/kg
R<32%
r<13% ICP-MS
0 mg/kg 1.0 mg/kg
0.89 mg/kg
0.76 mg/kg
NB: with excellent Laboratory Practice (GLP), r & R can be reduced in both
methods but will still be matrices dependant
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9. QUESTIONS TO YOU…
• Are you facing the same challenges?
• Is this discussed with your customer
/ authorities when testing differences arises?
• Often a 3rd-party independent lab is used to settle the
case but it doesn’t resolve the situation as this 3rd-
party lab is facing the same difficulties (r&R) – would it
not be better to agree first on a testing method
(preferably international) and associated acceptable
r&R? how could we move this forward?
…PLEASE SHARE WITH ALL
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