Sampling and analytical sensitivity – precision and complexity · include estimate of exp’...

Sampling and analytical sensitivity –precision and complexity

Elizabeth Owens – Divisional Manager Agriculture

PIX AMC Conference 2018 1

Planning to succeed with testing

www.symbiolabs.com.au

Testing the testUnderstand the limitsObtaining a representative sampleSample identificationMixer CV testingResults to meet contractual obligationsInterpreting results – when is it out of specificationWhat consumers expect versus what is practicalHow low can we go?


Testing the testNeed to comply with food safety and industry guidelines - Feedsafe™ and FIAAAHACCP plan will also identify check points and pass/fail criteria – OOS guidelinesFocus on

routine compliance testing and quality verificationProtocols to maximize success


Before you test• Need to know –

– what am I testing?– how do I get the best

sample? – am I using the right test?– what constitutes a

good/bad result?– what action will I take

based on a good/bad result?


Obtaining a representative sample• Labs only test a small portion of what you provide. So it MUST be

representative of the batch. • Sampling procedure will vary depending on type of sample and test

being conducted• Sampling error is most significant source of error in any analytical

result


Sampling protocols• Industry standards

specified by:– Codex General Guidelines on

Sampling– ISO standards– FAO Guidelines

• Simplest way to minimize sampling error is:– Take more samples across the

batch– Increase sample size– Employ the right instrument

for the job e.g. hay or grain probe or auto sampler


Sampling from forage• Differences exist in

concentration of most nutrients across a bunker –shown are variations in %DM and CP

• 12 – 20 samples should be taken using hay probe from “W” across face of bunker


7315

6312

6814

Other considerations

• Mycotoxins – Increased sample size

needed– Hot spots exist– 2 tests or multiple

samples maybe required

• Residue testing – Avoid delay in submission– Be aware of on site

contamination

• Microbiological samples– Must be in sterile container– Beware of on site contamination– Avoid delay in submission


Paperwork makes the testing workDetails are important. These forms generally come pre-completed to avoid confusion and yet….


PIX AMC Conference 2018 12This is all the information we often receive.

Sample identificationOn sample bag:

Description must match what is on the paperworkMay include number and/or dateCustomer and/or business name

On paperworkinclude estimate of exp’ concentration for target analyteSpecify test requiredConfirm if “as received” or DWB required


Mixer CV testing• Integral part of mixer performance validation• Target is ≤ 10% CV• Some important considerations for selection of:

– Target analyte– Sample collection– Test method used and it’s potential MU


Mixer CV testing• http://foodqualityandsafety.wfp.org/coeffic

ient-of-variation-calculator


http://foodqualityandsafety.wfp.org/coefficient-of-variation-calculator

Selecting the right analyte• The lower the ingredient

conc’n the higher the CV.• The CV is inversely

proportional to the √ # particles/sample. 5% CV requires at least 400 particles per sample of that analyte. Small uniform particle size is critical

Other considerations are:• Particle density• Electrostatic charge• Hygroscopicity• Flowability• Cost of testUnwise to use multiple analytes of differing concentrations


Analyte selection• Drugs often favoured due to density being close

to grain/protein meal ingredients and inclusion rate is often > due to extending with carrier.– Downside is that drug testing is more expensive

• Trace elements have higher density and low concentration BUT advantage of small uniform particle size and low cost testing.


Sample collection• Take multiple samples evenly spaced across batch

- minimum of 10 final samples• Take samples at discharge point (not out of bags)• Be aware of potential points of contamination for

target analyte• 200 grams ideal


Important to ensure that MU does not exceed target CVPIX AMC Conference 2018 19

What is measurement uncertaintyUncertainty is the quantification of the

doubt around a measurement resultResult = x ± u

Quantity value uncertainty

Uncertainty of measurement does not imply doubt about the validity of the measurement, on the contrary – knowledge of the uncertainty implies increased

confidence in the validity of a measurement result


Measurement UncertaintyIncludes consideration of:

PrecisionAccuracyBiasSystemic and random effects

These variables are also present during the sample collection phase and these contribute to the MU


Testing to meet contractual obligations• If MU is ±10%, is a CP

result of 45% a pass when the target is 50%?

• Should test replicates and report the avg to achieve improved confidence.

• Need to understand the potential MU of method and sampling variation before specification limits are set


Out of specification or within MU?


45% 48% 50% 52% 55%

Is the result a pass or a fail?• Understand the LOR, reporting

units and # decimal points in final result

• 49.6%=50% after rounding.• No such number as 0• What action will you take

based on the result? And on how many OOS results?


“Contaminants in feed” -how low can you go?• LOR influenced by:

– Research – usually in food safety

– Public health scare– Advances in equipment– Changes to regulations– Following change to MRL as an

artificial trade barrier

• Laboratories achieve lower LOD by:– ∆ injection volume– Alter extraction procedures– Use an alternate detector –

more sensitive or selective– Investing in new

equipment

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Change in reporting limits• Latest fluorescence

detectors (HPLC) allow quantification of compounds to ppt level= 1 second in 320 centuries

• NRS 2005 – screened for 28 compounds

• NRS 2018 – screened for >100 compounds with LOR of 0.01ppm

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End users expect “0”• USDA’s annual Pesticide Data Program

(PDP) for 2016 showed that there were 0.75 detections per sample for organic produce vs 3.2 detections/sample for conventional produce.

• 80% of the residues detected on conventional crops are at levels low enough so that they would not be considered as a violation of the organic rules because they are 20 times lower than the EPA tolerance

• Bottom line- chemists are pretty good at finding minute amounts of chemicals but this does not mean they are a health risk.


Implications for stockfeed industry• MRL’s are not specifically established for stockfeed ingredients.• Makes compliance difficult when no MRL set.• Legislation sometimes introduced with no analytical or scientific support.• Likely that # compounds screened will and the LOR will .

Symbio Alliance Laboratory and TrainingCredit APVMA

Summary• Robust safety plan that identifies

sources of contamination.• Recognize "tolerable” levels for

each contaminant.• Identify preferred suppliers.• Stick to Feedsafe/FIAAA

guidelines wrt labelling, addition rates, flushing and sequencing

• Get training in sampling techniques.

• Be vigilant with novel ingredients and new suppliers.


Find out more

www.symbiolabs.com.au0400705644


Sampling and analytical sensitivity – precision and complexity · include estimate of exp’...

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