Rapid Detection of Chemical Contaminants New Frontiers in Food analysis Dr. Anoop A. Krishnan Assistant Director Export Inspection Council Synergising Food Safety, Quality and Regulatory Dimension for Excellence in Food Ecosystem
Introduction DILUTE AND SHOOT
Introduction ❖ The contamination of food by chemical hazards is a worldwide public health concern and is a leading cause of trade problems internationally. ❖ Chemical contaminants may occur in our food from various sources. They typically pose a health concern, resulting in strict regulations of their levels by national governments and internationally by the Codex Alimentarius Commission. ❖ Analysis of relevant chemical contaminants is an essential part of food safety testing programs to ensure consumer safety and compliance with regulatory limits. ❖ Modern analytical techniques can determine known chemical contaminants in complex food matrices at very low concentration levels. Moreover, they can also help discover and identify new or unexpected chemical contaminants.
Introduction • In recent years, hyphenated techniques have received ever- increasing attention as the principal means to solve complex analytical problems. The power of combining separation technologies with spectroscopic techniques has been demonstrated over the years for both quantitative and qualitative analysis of unknown compounds in complex natural product extracts or fractions. • To obtain structural information leading to the identification of the compounds/speciation forms present in a crude sample resulted in the introduction of various modern hyphenated techniques, e.g., CE-MS, GC-MS, LC-MS, LC-ICPMS and LC-NMR.
Chemical contaminant-Sources Chemical contaminants can be present in foods mainly as a result of the use of ✓ Agrochemicals , such as residues of pesticides and veterinary drugs ✓ Environmental Contaminants - Heavy metal, Dioxins etc. ✓ Food processing Contaminants - Nitrosamines, PAH etc. ✓ Migration from food packaging materials - Phthalates etc. ✓ Toxins - Mycotoxins, marine bio toxins etc. ✓ Unapproved food additives and adulterants - melamine, Sudan dyes etc.
Cob web of Food safety
Evolution of analytical methodology Ref: Modified from Seiber, J. N.,Regulation of Agrochemicals, American Chemical Society, Washington, D.C., 1991.
Technical innovation in Instrumentation • The evolution of the analytical instrumentation used by various laboratories in the last seven years has drastically Whatever changed and new technical innovation and evolution have is there, come. The use of conventional detectors has decreased, giving way to triple quadrupoles , which are, without question, the find it! most widely used instruments for both gas and liquid chromatography. In GC, single quadrupoles and ion traps have been replaced by triple quadrupoles (LCMSMS/GCQQQ) • During the last years the introduction of liquid chromatography high resolution mass spectrometry (LC- HRMS) has become popular in pesticide residues laboratories. The advantages in getting exact mass of the analytes have been evaluated giving an important and new solution to common problems of these analyses.. Recently new GC-HRMS are intending to cover a similar position for typical GC pesticide residues.
Interdependence of Analytical steps Sampling Sample preparation is critical, any losses here... cannot be recovered afterwards! Sample The techniques employed here Processing/Homogenization decide if the overall method is • Multi-Residue, • Single-Residue Sample Preparation • Group-Specific (extraction, cleanup, concentration, digestion) All instrumental analysis techniques available have some inherent limitations in terms of … Instrumental Analysis Sensitivity, Selectivity, Robustness (matrix tolerance) Data Processing “Thus, sample preparation and instrumental analysis always have to be observed together”
Analysis of food contaminants ➢ One of the current trends in analytical chemistry is the method development for many optimized tools used in classical methods. ➢ The basic analytical approach involves an extraction using a suitable solvent/ digestion using acids, clean up to remove interfering matrix components, a chromatographic separation and a selective detection. ➢ It is not an exaggeration to say that the implementation of mass spectrometry (MS) as a detection technique has truly revolutionized the analysis of chemical contaminants in foods.
Analysis of food contaminants ➢ As opposed to element-selective or non selective detectors, MS can detect a wide range of compounds independent of their elemental composition and provide simultaneous quantitation and structural identification of detected analytes. ➢ Fast analysis , consumption of small amounts of samples and reagents, high sensitivity and automation are some of the most important goals desired to be achieved. ➢ More generic Multiresidue, Multiclass analysis methodologies with high sensitivity and expanded scopes, which include as many compounds and commodities as possible in a single method are being developed
Analytical Approach ➢ Whether a method is single or multiresidue in scope, it will include a series of discrete steps or unit processes whose ultimate goal is to detect and quantify specific chemicals at levels of interest , in a relatively complex food matrix. ➢ The matrix may contain hundreds or even thousands of natural and man-made chemicals which can potentially interfere with the analyte(s) of interest, often at concentrations many-fold higher than those of the analytes. It is a proverbial “needle in the haystack” undertaking. ➢ Thus, methods must be designed to take advantage of unique physical properties, such as polarity, volatility, and optical properties, and chemical properties (reactivity, complex formation, combustion characteristics) which allow the analyte to stand out from the forest of matrix-derived interferences.
Analytical Approach • Extraction: Remove the analyte from the matrix, leaving the bulk of the matrix behind as a filterable or non volatile mass. • Clean up: Remove unwanted coextractives by such operations as column chromatography, liquid-liquid partitioning, volatilization, or chemical degradation. • Modification: Convert the target analyte to a derivative which is more readily separated, detected, or quantitatively determined than the parent. Modification may be done pre- or post-cleanup, or after the resolution step in operations such as post-column derivitization. • Resolution : Separate the analyte from remaining interferences, usually by some form of refined chromatography
Analytical Approach • Detection — Obtain a response related to the amount of analyte present. Chromatographic detectors, spectrophotometers, and mass spectrometers are the mainstays for achieving this objective, although immunosorbent-based methods are coming into more common use. • Measurement — Relate the response of the analyte to some known standard, of the analyte itself or a surrogate with similar properties, for calculating the concentration in the original matrix. • Confirmation — Provide assurance that the primary method gives correct (i.e., accurate and precise) results, by use of a second, independent method. This has become much more important in recent years due to the emphasis on quality assurance/quality control (QA/QC ) in the analytical laboratory .
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
New Frontiers in Food Analysis GC/LC analysis Sample preparation Increasing selectivity QuPPe, MiniLuke GC-FID GC-ECD QuEChERS, Ethylacetate (SWET ) Increasing GC-NPD/AAS Microwave digestion selectivity GC-FPD/Ultra HPLC/ICP-OES MIPs/Immunoaffinity GC-MS (quad/TOF)/LCMSMS/LC-TOF Column chromatography GCxGC-MS, GC-MS/MS, GC-hrMS, LC-hrMS Solid Phase Extraction GCxGC-hrMS, GC-QTOF, IRMS, APGC, Traps Dispersive SPE Orbitrap/MS, MALDI-TOFMS, HPLC-ICPMS Selective extraction solvent Power to discriminate: Generic extraction solvent Isomers High Selectivity in Instrumental Analysis gives more flexibility in sample preparation Metabolites Megradation products Matrix components Endogenous compounds Recoveries • Safe • Speed/Time • Clean - up efficiency • Cost
New Frontiers in Food Analysis SPE dSPE Easy of Use/Efficiancy (time) Effective clean up
New Frontiers in inorganic analysis High ICP-OES LC/IC-ICPMS ICP-MS ASV Number of Fast Sequential elements AAS AAS- Flame AAS-Furnace Hydride Low High (mg/kg) Low (µg/kg) Detection limits
Analytical requirements
Analytical Interlink Check that Check that Check that Method is Laboratory can Method Works reliable use it Performance Proficiency Validation measurement Testing Combination should be fit-for-purpose
Challenges ✓ Need for fast, reliable, harmonised multimethods for analysis of a range of contaminants and unknowns ✓ Food fraud = Global issue
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