Analysis of Contaminants in Food

Transcription

1 Seminar on Contaminants in Food FSAI 17 th November 2009 Analysis of Contaminants in Food Michael O Keeffe Scientific Committee FSAI

2 Analysis of Contaminants in Food Residue analysis what is involved? Methods used Research advances New approaches Contaminants what are found? Closing comments

3 Aims of Residue Analysis in Food to identify the residue status of food using the least number of samples/tests 1. least interference with business (production, sale, shipment, etc.) 2. lowest cost of testing 3. highest assurance of food safety and/or compliance

4 Characteristics of Residue Analysis Target Sample Result Specific food item (carcase; milk tanker) Part of the food item (tissue sample; milk sample) Applicable only to the specific food item (sample/test method) HIGH s Specific batch of food (herd; milk silo) Sample(s) from the batch (tissue sample(s); milk sample(s)) Applicable to the batch (sampling/sample/ test method) u r Survey of food (retail products) Samples from multiple sources (multiple samples) Reflecting status of food covered by survey (design/sampling/sample/ test method) e t Monitoring programme (national herd; milk production) Samples covering the national production (range of samples) Reflecting status of food in national production (scope/design/sampling/ sample/test method) y LOW

5 What Do Results Tell Us? Expected Occurrence in the Population based on Test Results (95% confidence) Number of Positive Results Number of Samples % 0 20 % 0 4 % 0 1 % 0 % % 0 23 % 0 5 % 0 4 % 0 2 % % % 2 11 % 3 9 % 4 7 % If no positive in 297 random samples, occurrence in population is 1% (with 95% confidence) No residue detected in sample means just that!

6 How are Results Interpreted? F O O D M E T H O D Maximum Residue Limit (MRL) level of permitted drug allowed in a food Maximum Level (ML) up to level of a contaminant allowed in a food Minimum Required Performance Limit (MRPL) minimum content that must be detected Decision Limit (CCα)/Detection Capability (CCβ) - method capability to identify and measure Limit of Quantification/Detection (LOQ, LOD) measures of method sensitivity

7 Central Meat Control Laboratory State Laboratory Irish Equine Centre Ashtown Food Research Centre Pesticide Control Service, DAFF State Laboratory Pesticide Control Service Marine Institute Radiological Protection Institute Public Analyst Laboratories

8 Approaches to Residue Testing 1. Large numbers of samples for testing: SCREENING tests for similar contaminants (aflatoxins; antimicrobials; steroids) CONFIRMATORY tests 2. Samples for testing for large numbers of contaminants: multi residue CONFIRMATORY tests (antiparasitics; pesticides; dioxins)

9 Screening Tests Aim: rapid, inexpensive clearance of large numbers of samples as negative Immunoassays - Mycotoxins (ELISA) Veterinary Drugs Automated IAs - Veterinary Drugs (Biosensor) Cell Receptor Assay - Dioxins (e.g. CALUX) Inhibition Assays - Antimicrobials (Six-plate; DELVO)

10 Screening Test Dipstick Immunoassay immunoassay dipsticks sample extracts loading extract into sample well result shown as binding lines on pad

11 Screening Test Biacore Biosensor

12 Biacore Biosensor operation Incident light Reflected intensity Resonance angle: prism Gold film

13 Biacore Biosensor operation Incident light Reflected intensity Change of resonance angle by altered surface Binding of analyte flow

14 Biacore Biosensor measurement RESPONSE (RU) binding concentration stable complex regeneration TIME (s)

15 Confirmatory Tests Aim: accurate, specific, quantitative results for samples screened as query positive LC (or GC) mass spectrometry for Organic residues (Banned substances, Veterinary Drugs, Mycotoxins, Dioxins, Pesticides, etc.) LC (or GC) other detectors for Organic residues (permitted Veterinary Drugs, Mycotoxins, Pesticides) Atomic absorption/emission spectrometry for Heavy Metals

16 HPLC MS/MS CHROMATOGRAM OF MULTIPLE RESIDUES LC-MS/MS

17 Residue Analysis supported by Research

18 Components of a Residue Method Method: Nitroimidazoles in Liver (2007) Liver sample Repeat (x2) LC-MS/MS

19 Residue Extraction using QuEChERS Dispersive SPE - QuEChERS - mixing of a sorbent with sample extract in a mini-centrifuge tube to retain matrix interferents, but not the analytes No need for: SPE cartridges, apparatus, elution, evaporation Dispersive-SPE clean-up Mixed Extract Less sorbent, less time, less cost Better interaction of sorbent with sample extract for cleanup Fast, easy procedure

20 Residue Extraction using QuEChERS Developed for use in Pesticide analysis by USDA More than 250 Pesticides extracted with % (mainly %) recovery 38 drug residues included At AFRC Teagasc developed for anthelmintic drug residue analysis, combined with UPLC-MS/MS Good sensitivity achieved Replacing 3 methods Reducing analysis time ( 5) Reducing solvent waste ( 10)

21 Improvements in Chromatography HPLC MS/MS Feature UPLC MS/MS 5 µm 0.3 ml/min 30 C 32 min 242 particle size flow rate temperature run time measurements 1.7 µm 0.45 ml/min 65 C 16 min 344 Example: Pesticides in Fruit and Vegetables decreased run time expanded scope improved efficiency increased sensitivity more samples tested

22 Research guiding Testing Protein-bound Nitrofuran Residues Occur as bound residues in edible tissues, for long time after treatment Released by acid conditions of stomach as toxic metabolites (banned) Test method targets bound residues: Liver solvent washes acid incubation derivatisation released, derivatised nitrofuran metabolites ethyl acetate extraction (3 x 6 ml) LC-MS/MS

23 New Approaches to Testing Challenge how to detect hormone abuse in animals? conventional testing of only 0.05% of animals use of low level hormone cocktails and designer drugs Solution blood screening for indicator metabolites proteins, creatinine, enzymes, electrolytes, urea, glucose Confirmation by LC MS/MS analysis testing of hair samples where hormones accumulate

24 Indirect Testing Creatinine ( mol/l) ** Control Treated Steers treated with oestradiol Day Heifers treated with nortestosterone Creatinine ( mol/l) ** ** * * Control Treated Day

25 Indirect Testing Steers treated with oestradiol prediction success rate = 95.7% Heifers treated with nortestosterone prediction success rate = 91.4%

26 Ensuring the Quality of Testing Method Validation and Performance Criteria Method Accreditation Proficiency Testing 2002/657/EC ISO (INAB) FAPAS CRLs

27 What do the Results show?

28 Dioxins + PCBs Dioxins + Dioxin-like PCBs in Milk (pg WHO-TEQ/g fat) EPA Surveys Background Samples (n = 24) Potential impact Samples (n = 13) Mean Mean Max Max EU Regulation (1881/2006): 6 pg WHO TEQ/g fat BUT! see Rhod Evans story on Dioxins

29 Radioactivity Doses to Heavy Seafood Consumers (*) due to Radiocaesium (*200 g fish plus 20 g shellfish per day) Dose of radiation from naturally-occurring polonium-210 in seafood = 148 µsievert Conclusion: it is safe to eat seafood landed at Irish fishing ports

30 Marine Biotoxins Amnesic Shellfish Poisoning (ASP) toxins Azaspiracid (AZP) toxins Diarrhetic Shellfish Poisoning (DSP) toxins Shellfish Samples < ML > ML* (%) Samples < ML > ML # (%) Samples < ML > ML $ (%) Mussels (0.9%) (13.5%) (0.5%) Scallops (6.7%) (*20 µg/g domoic acid) ( # 0.16 µg/g AZP equivalents) ( $ 0.16 µg/g okadaic acid)

31 Pesticides Monitoring Programme for Fruit and Vegetables Profile: some 900 samples of 75 commodities tested each year (approximately 25% domestic and 75% imported) Testing: Year: Pesticides tested Pesticides found Results: 44% (2003) 59% (2007) samples contain pesticides 3% to 5% of these pesticides are at levels >MRLs

32 Are Pesticides a Food Safety Issue? Estimated Exposure of Children to 4 Pesticides, based on Food Consumption Pesticide ADI (mg/kg bw/d) mg Pesticide intake per kg body weight Mean % of ADI 97.5 percentile of intake mg % of ADI 99.9 percentile of intake Iprodione Thiabendazole Cyprodinil Chlorpyriphos mg % of ADI Conclusion: intake of pesticides by children are below ADI values

33 Veterinary Drugs Antimicrobials

34 Veterinary Drugs Antiparasitics Increased incidence of anthelmintics found with improved testing: Incidence of Non compliant Samples none 1 ovine 2 milk 1 bovine 5 milk 1 ovine 1 poultry Application of new method QuEChERS extraction coupled with UPLC-MS/MS

35 Veterinary Drugs Anticoccidialss Coccidiosis serious in poultry Nicarbazin a very effective drug Maximum limit: 200 µg/kg in liver Research leading to Improved Practices BUT! very difficult to eliminate

36 Veterinary Drugs Industry Self monitoring Directive 96/23/EC (S.I. 143/2007) applies for Foods of Animal Origin 2008 Self-monitoring Bovine Ovine Porcine Poultry Milk Antimicrobials 2329/0 Antimicrobials 3147/0 Antimicrobials 29025/0 Antimicrobials 2840/1 Antimicrobials /2108 Β Agonists 4121/0 Anticoccidials 379/0 Chloramphenicol 501/0 Anticoccidials 1160/30 Pesticides 383/0 Trenbolone 4183/0 Sedatives 161/0