Food Toxicants Analysis Book

Preface     v
Contents list     vii
Contributor contact details     xxi
Regulations
The international regulation of chemical toxicants in food: Codex Alimentarius   Maria Varadi     1
General principles of Codex Alimentarius     1
Operation of Codex Alimentarius     2
Decision making and enforcement mechanisms in Codex Alimentarius     4
Codex standard for contaminants and toxins in foods Codex Stan 193 1995 (Rev. 1-1977)     4
Scope     4
Definition terms     4
Contaminant     4
Natural toxins     5
Maximum Level     5
General principles regarding contaminants in food     5
General     5
Principles for establishing maximum levels (MLs) in foods and feeds     6
Specific criteria     6
Codex procedure for establishing standards for contaminants in food     6
Procedure for preliminary discussion about contaminants in the CCFAC     6
Procedure for risk management decisions in the CCFAC regarding contaminants     6
Format of the standard for contaminants in food     7
Types of presentation for the standards     7
Food categorization system     7
Description of the food categorization system of the GSC     7
Review and revision of the standard     8
Other codex standards and guidelines regarding contaminants in food     8
Different legislations on toxicants in foodstuffs   Peter Paulsen   Wolfgang Luf   Fran J.M. Smulders     11
Food toxicant and Food safety     11
Nature of toxicants     11
Occurrence and control of toxicants along the food chain     11
European Union     12
The EU White Paper on Food Safety     13
Food toxicants as addressed in the "new" EU food hygiene legislation and related legal texts     15
Legal texts dealing with specific substances with possible or factual adverse health effects     18
Toxins of bacterial origin     18
Contaminants, residues, food additives and substances formed during food processing     19
Legal requirements for detection methods     22
USA     23
Historical aspects     23
Organizational framework     24
Principles of food safety     25
Specific legislation     26
Mercosur legislation     27
Asia-Pacific Region     29
Concluding Remarks      29
Risk and Quality Assurance
Risk assessment of food additives and contaminants   Jim Bridges   Olga Bridges     33
Risk assessment procedures     33
The need for risk assessment     33
Hazard identification and characterisation     34
Use of animal tests     34
Use of epidemiology data     36
Use of other data     36
Dose considerations     37
Exposure assessment     37
Risk characterization     38
The issue of carcinogens     39
Methods for evaluating the risk from 'data poor' additives and contaminants     40
Regulation of food additives and contaminants     42
Overall conclusions on the risk assessment process     42
The case of Sunset Yellow     43
Food dyes and their regulation     43
Sunset Yellow FCF     44
Hazard identification and chaiacterization - animal findings     45
Human data     46
Assessment of intake     46
Consideration of Sudan1 - a contaminant of Sunset Yellow     47
Sudan 1. Hazard identification and characterization     47
Sudan 1. Risk characterization     48
Future of food risk assessment      49
Societal trends     49
The future challenge for risk assessment     50
Training needs     50
Quality Assurance   Roger Wood     53
Introduction     53
European Union - Food Control Directives     53
Codex Alimentarius Commission     56
Accreditation     57
Internal quality control: harmonised guidelines for internal quality control in analytical chemistry laboratories     58
Basic concepts     58
Scope of the guidelines     60
Internal quality control and uncertainty     60
Recommendations in the guidelines     61
Proficiency testing     63
What is proficiency testing?     63
Why proficiency testing is important?     64
ISO/IUPAC/AOAC International harmonised protocol for proficiency testing of (chemical) analytical laboratories     64
Organization of proficiency testing schemes     64
Methods of analysis     68
AOAC International (AOACI)     69
The European Union     69
The Codex Alimentarius Commission     69
Principles for the establishment of Codex methods of analysis     70
European Committee for Standardization (CEN)      71
Requirements of official bodies for methods of analysis     72
Collaborative trials     73
What is a collaborative trial?     73
IUPAC/ISO/AOAC International harmonisation protocol     73
The components that make up a collaborative trial     74
Assessment of the acceptability of the precision characteristics of a method of analysis     76
Summary requirements for a collaborative trial     77
Harmonised guidelines for single-laboratory validation of methods of analysis     78
Recovery factors: development of an internationally agreed protocol for the use of recovery factors     78
Sources of error in analytical chemistry     80
International guidelines     81
Recommendations     81
Measurement uncertainty     81
Conclusions     82
Methods of analysis being developed or published by the European Committee for standardisation (CEN) in areas of relevance to this text     84
Codex guidelines on measurement uncertainty     88
Molecular Biology Techniques     7
Immunoassays   N. Alice Lee   Ivan R. Kennedy     91
Overview of immunoassays     91
Advantages of immunoassays     91
Disadvantages of immunoassays     93
Principles of immunoassay     98
Development of immunoassay for food contaminants     99
Hapten synthesis     99
Selection of space arms and the point of attachment     101
Coupling procedures to carrier protein, enzyme and antibodies     104
Carboxylic groups-mixed function anhydride     104
Carboxylic groups-carbodiimide     105
Carboxylic groups-N-hydroxysuccinimide     106
Miscellaneous carboxylic methods     107
Hydroxyl groups     109
Amines     110
Carbonyl, phenols and thiol groups     113
Bifunctional reagents     115
Antibody production     115
Polyclonal antibodies     116
Monoclonal antibodies     117
Recombinant antibodies     117
Immunoassay formats     118
Immobilization     121
Antibody characterization     123
Sensitivity and limit of detection     125
Specificity     126
Matrix effect     127
Assay accuracy     129
Assay precision     131
Quality assurance and quality control     132
Reagent stability      133
Conclusion     133
Polymerase chain reaction (PCR)   Nelson Marmiroli   Elena Maestri     147
Introduction     147
Qualitative PCR     149
Multiplex PCR     149
Nested PCR     150
Reversed transcription PCR     151
Quantification with PCR     152
Quantitative conventional PCR techniques     152
Relative quantitative PCR     153
Absolute quantitative PCR     153
PCR with clamping     153
Quantitative PCR based on the 'Real-Time PCR' system     155
SYBR Green I chemistry     155
TAMRA quenched TaqMan probes     156
Other types of probes     160
High throughput genotyping with PCR     161
Restriction fragment length polymorphism (RFLP) of PCR-amplified fragments     161
Other genetic markers     162
Array systems     162
New trends in genotyping     162
Micro Total Analytical Systems ([mu]TAS)     162
Single molecule PCR     163
Immobilized PCR and DNA colonies     163
Good assay     163
Arrayed Primer Extension (APEX)     163
Fluorescent Amplified Fragment Length Polymorphism (FAFLP)     164
Analysis of toxicants     164
Food allergens     165
Mycotoxins and bacterial toxins     169
Fungal contaminants     170
Bacterial contaminants     172
Identification of genetically modified organisms (GMOs)     177
Predictive toxicogenomics     178
Conclusions and future trends     181
Analysis of food allergens. Practical applications   Arjon J. Van Hengel   Elke Anklam   Steve L. Taylor   Sue L. Hefle     189
Introduction     189
Methods for the detection of allergens     194
Rast/East inhibition     194
Immunoblotting     194
Rocket immuno-electrophoresis     195
Elisa     195
Dipsticks     197
Biosensors     197
PCR     198
Cell response factor release assay     200
Proteomics     201
A selection of food allergens and their detection     202
Peanuts     202
Characteristics of peanut allergy     202
Peanut allergenic proteins     202
Peanut detection methods      202
Comparisons/validation of commercial peanut detection kits     205
Milk and dairy products     207
Characteristics of milk allergy     207
Milk allergenic proteins     207
Milk detection methods     208
Eggs and egg products     210
Characteristics of egg allergy     210
Eggs allergens     210
Egg detection methods     211
Crustaceans     212
Characteristics of crustacean allergy     212
Crustacean allergens     212
Crustacean detection methods     213
Fish     213
Characteristics of fish allergy     213
Fish allergens     214
Fish detection methods     214
Conclusions     215
Case studies     215
Summary and outlook     216
Sampling, detection, identification and quantification of genetically modified organisms (GMOs)   Arne Holst-Jensen     231
Introduction     231
Genetically modified organisms (GMOs)     231
GMOs on the world market     233
The analytical procedure     235
Analyte relationships and associated characteristics     237
Sampling      238
Analyte purification     240
Characterising GMOs     243
DNA sequence based characterisation     243
RNA based characterisation     244
Protein based characterisation     245
Metabolite based characterisation     245
Detecting GMO derived analytes     246
Establishing the GM quantity     246
The unit of measurement and expression of GM content     249
Protein based detection methods     249
RNA based detection methods     250
Metabolite based detection methods     250
DNA based detection methods     251
Target specificity     251
Technologies applied to DNA based GMO detection     254
Qualitative detection methods     255
Quantitative detection methods     256
Detection and quantification limits     259
Reference materials     260
Method validation and performance reliability     261
Concluding remarks     263
Screening and Chromatographic Methods
Extraction procedures   Sara Bogialli   Antonio Di Corcia   Manuela Nazzari     269
Introduction     269
Analyte extraction from liquid foodstuff      269
Liquid-liquid extraction     269
Solid-phase extraction     271
Techniques based on sorptive extraction     274
Solid-phase microextraction     275
Stir-bar sorptive extraction     277
Supported liquid membranes     278
Analyte extraction from solid foodstuff     279
Soxhlet extraction     280
Liquid-phase extraction     280
Supercritical fluid extraction     281
Microwave-assisted extraction     284
Pressurized liquid extraction     286
Matrix solid-phase dispersion     288
Clean-up and fractionation methods   Dimitrios J. Fletouris     299
Introduction     299
Nature of interferences     300
Methods based on partitioning     304
Conventional liquid-liquid partitioning     304
Ion-pair partitioning     306
Other liquid-liquid partitioning approaches     307
Methods based on chromatography     308
Adsorption chromatography clean-up     309
Partition chromatography clean-up     311
Ion-exchange chromatography clean-up     314
Size-exclusion chromatography clean-up      317
Clean-up based on molecular recognition     319
Immuno-based clean-up     319
Molecular imprinting clean-up     327
Co-distillation/forced volatilisation methods     333
Precipitation clean-up methods     334
Chemical clean-up methods     336
Final remarks     337
Automated clean up techniques   Hans G.J. Mol     349
Introduction     349
Scope     349
Reasons for clean up in food analysis     350
Rational of automated clean up     354
Reasons to automate clean up     354
Reasons not to automate clean up     355
To automate or not?     355
Relative backwardness of automation in food toxicant analysis     356
Approaches for automated clean up: off-line vs on-line     357
Automated off-line clean up approaches     359
SFE and PLE     359
GPC     362
SPE     364
HPLC     368
On-line clean up approaches     372
Clean up coupled to GC     372
Headspace techniques     372
Automated combined extraction/clean-up with GC analysis     374
Automated membrane based clean up     376
Automated clean up in the GC inlet     378
SPE-GC     380
GPC-GC     380
LC-GC     383
LCxGC     386
GC-GC     386
Comprehensive GCxGC     386
Clean up coupled to LC     390
Combined extraction/clean up coupled to LC     390
SPE-HPLC     393
LC-LC (column switching)     410
LCxLC     410
Concluding remarks     411
Gas chromatography-mass spectrometry (GC-MS)   Jana Hajslovd   Tomas Cajka     419
Introduction     419
Matrix effects     420
Sample introduction     426
Split/splitless injection     427
Cold on-column (COC) injection     428
Programmable temperature vaporisation injection (PTV)     429
Direct sample introduction (DSI)/ Difficult matrix introduction (DMI)     432
Solid-phase microextraction (SPME)     434
Gas chromatographic separation     434
Fast GC     436
Practical approaches to fast GC analysis     437
Instrumental requirements in fast GC     440
Multidimensional high resolution GC      444
Comprehensive two-dimensional gas chromatography (GCxGC)     446
GCxGC set-up     446
Optimisation of operation conditions and instrumental requirements in GCxGC     446
Application of GCxGC, examples of merits     450
Mass spectrometric detection     454
Ionisation techniques     454
Electron ionisation (EI)     454
Chemical ionisation (CI)     455
Mass analysers     456
Quadrupole instruments     457
Ion-trap instruments     457
Time-of-flight instruments     459
Double-focusing magnetic sector instruments     459
Tandem mass spectrometry     460
Applications of GC-MS to food toxicants analysis     463
Pesticides     463
Polychlorinated biphenyls (PCBs)     464
Polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDDs/PCDFs), dioxine-like polychlorinated biphenyls and dioxine-like PCBs     465
Polybrominated diphenyl ethers (PBDEs)     466
Polycyclic aromatic hydrocarbons (PAHs)     469
Mycotoxins     470
Veterinary drug residues     470
Acrylamide     470
Chloropropanols     471
Liquid chromatography with conventional detection   Mervi Rokka   Marika Jestoi   Susanna Eerola     475
Introduction     475
Separation modes for food toxicant analysis     476
Detection systems     476
UV-VIS detection     476
Fluorescence detection     486
Electrochemical detection     495
On-line combination of multiple detectors     499
Conclusion     499
Liquid chromatography-mass spectrometry   Cristina Blasco   Yolanda Pico     509
Introduction     509
Liquid chromatographic separation     510
Interfacing systems     518
Matrix effects     523
Mass analyzers     528
Single quadrupole     528
Time-of-flight     531
Tandem mass analyzers     535
Triple quadrupole     535
Quadrupole ion trap     539
Hybrid Quadrupole time-of-flight     543
Applications     545
Pesticide residues     545
Veterinary drugs     546
Food packaging migrating products     548
Mycotoxins     548
Algae and fish toxins     549
Heat induced decomposition products     549
Food additives     550
Toxic food constituents     551
Conclusions and future trends     551
Capillary electrophoresis   Agnes Fekete   Philippe Schmitt-Kopplin     561
Introduction     561
Principles of capillary electrophoresis     561
The driving force in the capillary: the electroosmotic flow (EOF)     563
The theory of zone electrophoresis for charged colloids and molecules     565
The most important techniques in brief     566
Capillary zone electrophoresis (CZE)     566
Micellar electrokinetic chromatography (MEKC)     567
Chiral CZE and chiral MEKC     568
Capillary gel electrophoresis (CGE)     569
Capillary electrochromatography (CEC)     569
Application of capillary electrophoresis in food analysis     570
CZE methods for food contaminants and components     571
Veterinary drugs     571
Pesticides     575
Biological origin toxins     575
Inorganic ions and low molecular weight acids     580
Amines and amino acids     581
Phenolic compounds and vitamins     583
Carbohydrates      584
Proteins     584
MEKC methods for food contaminants and components     586
Pesticides and toxins     586
Amino acids, additives and proteins     587
Chiral CZE and chiral MEKC for food contaminants and components     588
Pesticides  &n