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Programme Partners Funded by Trends in Food Contaminants and Residue Analysis Dr. Margarita Corrales International Consultant FAO-Bangladesh
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Food contaminants dhaka university_august2014

Jun 30, 2015

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Food contaminants Dhaka University August 2014
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Page 1: Food contaminants dhaka university_august2014

Programme Partners Funded by

Trends in Food Contaminantsand Residue Analysis

Dr. Margarita CorralesInternational ConsultantFAO-Bangladesh

Page 2: Food contaminants dhaka university_august2014

What are Food Contaminants?

• Contaminants are substances that can unintentionally enter food during its production or marketing.

• Residues are also food contaminants but occur in foodstuffs as traces or derivatives thereof from the use of agrochemicals or food processing

Page 3: Food contaminants dhaka university_august2014

Food Contaminants

• Naturally occurring toxicants – Aflatoxins – Ochratoxins..

• Improper use of Agrochemicals– Pesticides, veterinary drug residues

• Industrial and environmental pollutants– Heavy metals, Dioxins, Polychlorinated biphenyls (PCBs)..

• Food Additives over permitted levels– Dyes, sweeteners, antioxidants..

• Emerging chemical hazards– Process-related: Acrylamide, furans, polycilic Aromatic Hydrocarbons (PaHs)– Adulterants:Melamine

Page 4: Food contaminants dhaka university_august2014

Maximum Residue Levels (MRLs)

• MAXIMUM RESIDUE LEVELS (MRLs) are the upper legal levels of a concentration for residues in or on food or feed based on good agricultural practices and to ensure the lowest level of exposure

• AIMS:– Protect consumers– Ensure fair trade practices in the food trade– Promote coordination of all food standards work

undertaken by international governmental and non governmental organisations

Page 5: Food contaminants dhaka university_august2014

Codex Alimentarius MRLs

Pesticide Food Commodity *MRL [mg/kg]

Endosulfan Poultry meatPotatoTomato

0.030.050.5

Methyl Parathion ApplePotatoCabbage

0.20.050.05

* Codex Alimentarius Commission

Regular upgrading of national standards and MRLs in line

with international standards

Page 6: Food contaminants dhaka university_august2014

Food Contaminant Control

Ideal Situation • Rigorous controls• Identify the main sources of contamination (raw materials,

supply chain)• New emerging pathogens and contaminants

Needs• Improve prevention, detection and control strategies along

the food production chain• Use powerful and sophisticated technologies• Anticipate and control emerging pathogens, new

contaminants• Develop methods for the unequivocal identification/detection

of potential chemical contaminants

Page 7: Food contaminants dhaka university_august2014

Methods of Analysis, Detection and Control

Aspect1 : Screening Procedures • Fast, cheap, reliable• Portable, field, in/on-line• High sample throughput • Selective <-> Multi- Analyte/Residue/ Pathogen• Stable & robust• Low LoD & LoQ• Test-Kits & sensors

Aspect 2 : Confirmatory Procedures • Sophisticated & reliable• Selective <-> Multi- Analyte/Residue• Stable• Low LoD & LoQ• Low solvent extraction• Selective clean-up step• Selective end-point• e.g.LC-MS-MS,GC-MS-MS, • Matching screening procedure(s)

Aspect 3 : Reliability

• Intra-lab quality control / assurance• Inter-lab quality control / assurance• Acceptance criteria • Low suspected false negative & positive results• Benchmarking• Accreditation• Standardisation (guide)• Communication (results)

Page 8: Food contaminants dhaka university_august2014

Aspect 1: Screening ProceduresField rapid, reliable sensitive methods

Dipstick methodColorimetric testsBionanosensorsTime Resolved Fluorometres (veterinary drugs)

Interlaboratory Method Validation

Detection of sulfonamides, tylosin, chloramphenicol and fluoroquinolones in honey

Page 9: Food contaminants dhaka university_august2014

Aspect 2: Confirmatory Methods

• Sample Extraction• Sample Clean-up• Analysis by high throughput technologies

– High Performance Liquid Chromatography• UV-Detector• Fluorescence detector• Mass Detector/ tandem mass spectrometry (MS/MS)

– Gas Chromatography• Electron Capture Detector• Flame Ionisation Detector• Mass Detector/tandem mass spectrometry (MS/MS)

– Atomic Absorption Spectrometry

Page 10: Food contaminants dhaka university_august2014

Multi-Residue/Analyte Methods

Analysis of 300 pesticides in 30min by LC-MS/MS

GOAL

Page 11: Food contaminants dhaka university_august2014

Mission of the National Food SafetyLaboratory (NFSL)

• Act as Reference Laboratory related to Food Safety Examination and Procedure

• Analysis of food samples collected by sanitary inspectors as per standard

• Reporting of results after sample analysis• Conduct research and training programmes related to

food safety• Coordinate and networking with all laboratories related

to food safety

Page 12: Food contaminants dhaka university_august2014

Selection of Methods (ISO 17025)

• Published in international or national standards• Published by reputable technical organisations• Published in scientific journals• Specified by the manufactures of the equipment• In-house developed laboratory methods

Methods have to be validated !!

Page 13: Food contaminants dhaka university_august2014

Aspect 3: Reliability

• Method Validation is to:– Identify an analyte in a test sample– Quantify accurately an analyte in a test sample

• Method Validation is to provide evidence that a method is fit for purpose. It does what it’s intended to do with high level of precision and accuracy

• A properly validated method should provide confidence in the results

Method Validation

Page 14: Food contaminants dhaka university_august2014

Method Validation Parameters

• Specificity/Selectivity• Linearity• Range• Limit of Detection• Limit of Quantification• Accuracy/Trueness• Precision/Repeteability• Reproducibility• Ruggedness/Robustness

Page 15: Food contaminants dhaka university_august2014

Method Selectivity

• The identification of a target analyte is correct and not hindered by the presence of one or more interferences

• The presence of interferences is not leading to a false positive

• The quantification is correct and not influenced notably by the matrix

• Selectivity can be confirmed using a matrix-added calibration curve

Page 16: Food contaminants dhaka university_august2014

Linearity / Range

• The regression analysis of test results vs analyte concentration must be linear.

• The linearity must cover the range of the expected concentration

0

500

1000

1500

2000

2500

3000

3500

4000

4500

0 50 100 150 200

Concentration

Peak

Are

a

Page 17: Food contaminants dhaka university_august2014

LOD and LOQ

Limit of Detection (LOD): It is the point at which an analysis is feasible

Limit of Quantification (LOQ): Concentration at which quantitative results can be reported with a high degree of confidence.

Limit of QuantificationSignal / Noise Ratio 10:1

Limit of DetectionSignal / Noise Ratio 3:1

Signal-to-noise examples

Page 18: Food contaminants dhaka university_august2014

Accuracy/Recovery

• Accuracy is a qualitative term referring to whether there is agreement between a measurement made on an object and its true (target or reference) value.

• Accuracy can be assessed on samples spiked with known amounts of the analyte

• At least 3 repetitions at 3 concentration levels (low, medium and high)

• Accuracy can be expressed as percentage recovery from the added amount with confidence intervals

Acceptance Criteria (AOAC). Recoveries ≥ 80%

Page 19: Food contaminants dhaka university_august2014

Precision/Repeteability

• Calculation of the (relative) standard deviation of a sufficient number of sample aliquots. This can be of three levels, three repetitions or 6 determinations at 100%.

Acceptance Criteria (AOAC) ≤ 15%

Page 20: Food contaminants dhaka university_august2014

Reproducibility

• Multiple chemists in multiple labs run samples. Results should be reproducible and comparable for method precision.

• Example: Samples run by 3 Chemist, 3 labs and 3 different instruments, 3 different days

20

Page 21: Food contaminants dhaka university_august2014

Robustness

• Change some method parameters and compare the differences with the core method

• Shows the reliability of the analytical method with respect to variations in the method

• Some parameters that can be changed:

- pH - temperature- % Organic

- buffer Concentration- column Lot

21

Page 22: Food contaminants dhaka university_august2014

Example 1: Organochlorine Pesticides by GC-ECD

GC-ECD Chromatogram of 20 organochlorine pesticides spiked at a concentration of 200ng/ml in dry fish (matrix-matched). α-BHC, Rt: 3.26; 2) δ-BHC, Rt: 3.69; 3) β-BHC, Rt:3.82; 4) γ-BHC, Rt:4.10; 5) Heptachlor, Rt: 4.46; 6) Aldrin, Rt:5.01; 7) Heptachlor Epoxide, Rt: 6.26; 8) γ-Chlordane, Rt:6.55; 9) α-Chlordane, Rt: 6.87; 10) α-Endosulfan, Rt: 7.14; 11) 4 ,4’ DDE, Rt: 7.15; 12) Dieldrin, Rt: 7.77; 13) Endrin, Rt: 8.35; 14) 4,4’ DDD, Rt: 8.70; 15) β-Endosulfan, Rt: 8.99; 16) 4, 4’DDT, Rt: 9.59; 17) Endrin Aldehyde, Rt: 10.42; 18) Endosulfan sulphate, Rt:11.78; 19) Methoxychlor, Rt: 12.24; 20) Endrin Ketone, Rt:13.60.

Multi-Residue Method for determination of organochlorine pesticides in fish

Page 23: Food contaminants dhaka university_august2014

Validation ResultsMatrix free Matrix Match (Loiytta Fish)

Pesticide R2 LOD [ppb]

LOQ [ppb]

Range [ppb]

R2 LOD [ppb]

LOQ [ppb]

Range [ppb]

α-BHC 0.99 22.33 74.44 25-500 0.99 61.40 204.67 50-500δ-BHC 0.99 23.09 76.98 25-500 0.99 55.90 186.36 50-500β-BHC 0.99 48.91 163.05 50-500 0.99 37.19 123.98 50-500 γ-BHC 0.99 50.87 169.59 50-500 0.99 69.56 231.87 50-500Heptachlor 0.99 23.81 79.38 25-500 0.99 37.38 124.61 50-500Aldrin 0.99 8.50 28.33 10-500 0.99 63.33 211.11 50-500

Pesticide (Spiked Level 80[ng /g])

Recovery [%] RSD [%]Repeatability

RSD [%]Precision

α-BHC 89.61 11.68 3.76δ-BHC 85.79 6.99 3.19β-BHC 107.12 6.50 9.24Heptachlor 99.96 5.04 13.01Heptachlor Epoxide 100.31 10.12 16.86γ-Chlordane 83.67 16.57 8.92

α-Chlordane 86.82 16.46 7.67

Page 24: Food contaminants dhaka university_august2014

Example 2: Formalin Detection by HPLC

1 2 3 4 5 6 7 8 9 10 11

10 6

20 6

30 6

40 6

Time [min]

Pea

k A

rea

[u

V]

1 2 3 4 5 6 7 8 9 10 11

Pea

k A

rea

[u

V]

10 6

20 6

30 6

40 6

Time [min]

A)

1 2 3 4 5 6 7 8 9 10 11

10 6

20 6

30 6

40 6

Pea

k A

rea

[u

V]

Time [min]

B)

1 2 3 4 5 6 7 8 9 10 11Time [min]

Pea

k A

rea

[u

V]

10 6

20 6

30 6

40 6C) D)

1 1

2

1 1

2

Selectivity HPLC Chromatogram: DNPH (A); 2mg/L derivatized standard (HCHO-DNPH (B); derivatised mango sample (spiked with 5mg/L formaldehyde). 1: DNPH, 2:CH2O

METHOD VALIDATION PARAMETERS: Formalin in FoodsParameter Matrix-free Matrix-matched

Mango Milk FishLinear Equation y= 488092x +

4440.9y=209862x +

189675y=202380 + 52100 y=27507.17 +

125966.7

R2 0.99 0.99 0.99 0.99LOD [mg/L] 0.39 0.32 0.67 1.75LOQ [mg/L] 1.30 1.08 2.23 5.83Range [mg/L] 1.30-250 1.08-150 1.0-150 5.0-150

Page 25: Food contaminants dhaka university_august2014

Moving Forward

• Bangladesh Food Safety Laboratory Network– Harmonisation and upgrading of analytical methods

in the country– Improve the level of confidence of analytical results– Interlaboratory comparison– Provide scientific-based data to support legislation– Support authorities in the control and monitor of

improper business practices.

Page 26: Food contaminants dhaka university_august2014

Programme Partners Funded by

Thank you for your attention