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METHOD SELECTION FOR FOOD

SAFETY AND QUALITY TESTING

Dr. Chuanhong Tu, Technical Manager, Analytical

Service Laboratories, Global Quality, Coca-Cola

Company , Shanghai

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Overview

• General guidelines on method selection

• Method selection for pesticide residue analysis

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Key elements on testing

Testing

Personnel

Equipment

EnvironmentalMaterial

Method

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Testing needs of customers

• Meet customer needs and appropriate for the tests

• Defining customer needs

• Sample type

• Target items

• Qualitative/Quantitative

• Reporting limits

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Selection of methods

• Standard methods preferred

• ISO, Codex, AOAC, ASTM, CEN, etc

• Reputable technical organization

• USFDA, USDA, EURLs, FSSAI etc

• Relevant scientific publications

• Laboratory-developed/adopted method

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Questions to ask• Is based on sound underlying scientific principles

• Is applicable for routine analysis of samples

• Can detect analytes in the concentration range of interest

• Has sufficient specificity and sensitivity for intended use

• Can meet specific method performance criteria

• Has adequate QA/QC controls

• Can be performed with readily-available equipment

• Can be conducted for a reasonable cost

• Addresses the level of expertise required

• Addresses waste disposal or biosafety concerns

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Example

Select methods for

pesticide residue analysis

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Testing kits: immunoassay

From http://www.horiba.com

• Preliminary screening for particular known compounds• Advantage: low cost, speed and ease of use• Limitation: individual or small group of compounds only

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Testing kits: enzyme inhibition

• Acetylcholinesterase inhibition

• broad spectrum for OPP and N-methyl carbamates

• Sensitivity at ppb-ppm level

• Quick, easy operation

• Need confirmation for violates.

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Multi-residue methods with selective detectors

FDA PAM Section 302, for non-fatty food

Luke method

• LLE extraction-cleanup-determination

• Robust, selective detections.

• Multi-class compounds

• Limitation

• Labor-intensive

• waste disposal

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Multi-residues with chromatography-MS detectors

10 g sample + 10 mL acetonitrile, Shake

4 g MgSO4 + 1 g NaCl, Shake and centrifuge

Determination by GC/MS and LC/MS/MS

Transfer X mL acetonitrile extract

X*0.025 g PSA and X*0.15 g MgSO4, Shake

and centrifuge

Transfer acetonitrile to vials for injection

QuEChERS sample preparation

• AOAC method 2007.01

• BS EN 15662: 2008

• quick, easy, cheap, effective,

rugged, and safe

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Dutch Mini-Luke preparation

Sample prep time per sample by method

• 1/10 solvent used compared

with original Luke

• Similar high throughtput with

QuEChERS

• Determination

• LC/MS/MS

• GC/MS/MS vs. GC/MS

From Food Chemistry 192 (2016) 668-681 by Ana Lozano etc.

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Better Sensitivity and selectivity with GC/MS/MS

From Agilent by Chris Sandy and ChinKai Meng

10 µg/L p,p’-DDE in matrices, 1µL injection

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Non-target screening

Pesticides Residues

Known Known Known Unknown

Target analysis by triple Q MS

Non-target analysis by high resolution MS (QTOF

or Orbitrap)

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Methods to Confirm Identification

• USFDA PAM requirements

• Mass spectrometry is a must for the first identification

• Chromatography with different parameter for previously identified

• EU AQC and Method validation procedures for pesticide residue analysis (SANTE/11945/2015)

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