The Technologies of Chemical Metrology and Quality Assurance of Measurement Results in Food Analysis

Transcription

1 The Technologies of Chemical Metrology and Quality Assurance of Measurement Results in Food Analysis Prof. Li Hongmei National Institute of Metrology, China (NIM, China) National Research Center of Certified Reference Materials(NRCCRM)

2 Outline 1. Background 2. Metrological Traceability in Analytical Chemistry Concept of metrological traceability Key factors of measurement quality control Method development CRM production Proficiency test 3. Establishment of the global measurement system in mycotoxins 4. Summary 2

3 The measurement Results are accurate or not? Measurement methods An inter-laboratory comparison held by EU in the year of 2000 Pre-preparation and reagent Reference material Operator and environment Key factors for chemical measurement Measuring instrument Others

4 Chemical metrology system Traceability: NMIs develop and establish the unbroken metrological traceability chain by providing the services of CRMs, PT and results assessment etc. Comparability:The transverse connection of metrology, calibration and testing laboratory at different level SI unit Globally effective Primary Method PRM High Accuracy Method CRM Standard Method analysis One time measurement

5 Chemical Metrology vs. Free Trade One Test Global Recognition Free Trade Mutual Recognition Comparability Traceability Test The Role of Chemical Metrology

6 Sustainable Economic Development Sustainable Economic Development Promoting trade Improving products product application (market access) product application (consumer protection) specialized production Precision Product Quantification Product Conformity Product Consistency Measurement Quality Assurance Metrology Conformity Assessment Standard

7 Reference Measurement Systems supports food safety International Mutual Chemical Recognition System: Metrology International Organizations System CRM: The key role 7

8 Grain food is a major nutrition source. Among 10 largest grain exporting countries in the world, 6 are from APEC, such as the United states, Australia and Canada. Grain safety main concerned with different contaminants, like mycotoxins, heavy metals, pesticide residue, microorganism, etc.. Among them, mycotoxins and heavy metals are two major harmful influence factors. Grain safety is the basis of national economic security, and is the core of the production, processing, trade, reserve and consumption balance. Measurement and standards provide accurate and internationally recognized methods to assure grain safety. The role of of measurement and standards in grain food Harmonized global measurement and standards can improve quality control system in developing countries, reduce economic loss and trade disputes.

9 Outline 1. Background 2. Metrological Traceability in Analytical chemistry Concept of metrological traceability Key factors in quality control of measurement Method development CRM production Proficiency test 3. Establishment of the global measurement system in mycotoxins 4. Summary 9

10 2.1 Metrological Traceability Metrological Traceability VIM definition: Property of a measurement result whereby the result can be related to a reference through a documented unbroken chain of calibrations, each contributing to the measurement uncertainty. The term Traceability is replaced by Metrological traceability a new definition as property of a measurement result which can be related to a reference an evidence of measurands tracing to the primary standards which can realize the SI units a documented unbroken chain of calibrations ISO/IEC Guide 99:2007, International vocabulary of metrology Basic and general concepts and associated terms 10

11 Unbroken chain of calibrations SI /Reference Measurement standard Measurement procedure Calibration Measurement unit Document Calibration Document Calibration Document Measured Results Results Measurements uncertainty & Measurements value 11

12 Outline 1. Background 2. Metrological Traceability in Analytical chemistry Concept of metrological traceability Key factors in quality control of measurement Method development CRM production Proficiency test 3. Establishment of the global measurement system in mycotoxins 4. Summary 12

13 2.2 Key factors in quality control of measurement Measurement standards and tools for metrological traceability Method Primary methods High accuracy methods Reference value for PT Chemical metrology CRM Pure / solution CRM Matrix CRM 13

14 Traceability 2.2 Key factors in quality control of measurement Common reference Higher level reference Higher level reference Calibration CRM1 comparability Calibration CRM2 Sample Matrix CRM1 Matrix CRM2 Sample Measurement result1 Bias Bias Measurement result2 comparability 14

15 2.2 Key factors in quality control of measurement Core capability principles in establishing chemical metrological traceability system Sample preparation techniques Medicine Environment Forensic science Security Food safety Measurement characteristics Advance material Measurement techniques Energy 15

16 Outline 1. Background 2. Traceability control in chemical metrology Concept of metrology traceability Key factors in traceability control Method development CRM production Proficiency test 3. Traceability system establishment in mycotoxin 4. Summary 16

17 2.3 Method development Purity assessment of organic compound-mass Balance Approach (MBA) P=1-W RS -W W -Wv-W NV The related structure impurities Water content VOCs Non-volatiles Qualitative analysis by GC- MS, LC-MS Karl Fischer titrator headspace GC- MS / headspace GC-FID Ash residue method, TGA or ICP-MS Quantitative analysis by GC, LC, GCMS,LCMS Verify by TGA Verify by q- NMR,TGA Verify by TGA 17

18 QNMR Procedure Advantage Selection of internal standard Selection of solvent Selection of quantitative peaks Optimization of qnmr paramemeters Potential primary method Traceability can be established to SI units Universal to almost organic compounds Simple pretreatment, which may decrease uncertainty No identification of impurities of water, solvent, inorganic One peak from analyte and one peak from internal standard is enough Determination 18

19 Measurement calibration Chemical components measurement result and influence factors on metrological traceability Method of matrix sample Definition of measurement Sampling Inaccurate or incomplete definition of the measurement Matrix effects Sample measurement data processing and uncertainty evaluation Result and application Instability of chemical composition ; Complicated sample transformation measurement process Complicated uncertainty components and combination method Isotope Dilution Mass Spectrometry --high accuracy method!!! 19

20 Isotope Dilution Mass Spectrometry Relative measurements, excellent precision and accuracy compared with standard additions Ideal internal standard (the same compound), Correction for signal drift and matrix effects Quantitative separation processes are not required Once equilibration of the spike and analyte isotopes has been achieved, the total recovery of the analyte is not required

21 CRM value assignment procedure by IDMS in organic targets Optimizing mass spectrometry conditions Optimizing chromatographic conditions No Matrix sample test Yes Preparation of stable isotope labeled standard solution Ratios of analyte to isotopic internal standard Matrix sample test No Yes Value assignment International comparison 21

22 IDMS technique can effectively compensate the matrix effect in some situation, matrix, instrumentation and other factors may still give rise to variation of the peak area ratio of analyte to isotope and consequently lead to unpleasant result. Key points of IDMS method Sample preparation Chromatographic Separation Mass spectrum detection Extraction recovery Remove matrix Interferences concentration Resolution high throughput high efficiency Matrix effect sensitivity selectivity accuracy 22

23 Matrix effect -- Chromatographic Separation Effect of composition of mobile phase and sample solvent on θ Chloramphenicol in milk powder 1.05 The factor of matrix effect (θ) % 35% 30% Acetonitrile in mobile phase 25% 30% 35% 40% Acetonitrile in dissolution solvent When the content of acetonitrile in the mobile phase was increased, the difference in ME of CAP and D5-CAP was getting smaller, or even disappeared. 23

24 Matrix effect -- Mass spectrometry detection ME of Melamine in Milk Powder NH 2 NH 2 15 NH 2 15 NH 2 N H 2 N N NH 2 N N N 6 N 13 H 2 N N NH H 2 N N NH 2 13 N N N 15 H 2 N N NH 2 Melamine 13 C3-Melamine 15 N3- Melamine 13 C3-15 N3-Melamine IS Increased mass Total mass The ratio( %) 13 C 3 -melamine C 3-15 N 3 -melamine N 3 -melamine

25 The ratio of the peak area Matrix effect -- Mass spectrometry detection Response Ratio of Melamine to Internal Standards N 13 C- 15 N average:1.35 average: The ratio of peak area (melamine / 15 N 3 -melamine) The ratio of peak area(melamine / 13 C 3-15 N 3 -melamine) The ratio of peak area(melamine / 13 C 3 -melamine) C average: The concentration of analyte,ug/kg Different response ratio has been found in melamine to three internal standards with same concentration, average values are 0.97, 1.27 and 1.35 respectively.

26 Uncertainty evaluation Chloramphenicol in milk powder Sample weighing Calibration solution Uncertainty account for :57% Purity Balance calibration weighing Balance linearity Temperature Standard solution D5-CAP dilution CAP dilution separation Clean up components matrix Column evaluation efficiency SPE evaluation Volumetric flask enrichment separation transfer extraction Method parameter efficiency Matrix removal repeatability Linear range matrix calibration CAP in milk powder MS condition solvents instrument Instrumental optimization Matrix effect Pretreatment, chromatography separation, Sample solution Uncertainty account for :43% 26

27 Uncertainty evaluation Uncertainty evaluation--chloramphenicol in milk powder 57% 27

28 Outline 1. Background 2. Metrological Traceability in Analytical chemistry Concept of metrological traceability Key factors in quality control of measurement Method development CRM production Proficiency test 3. Establishment of the global measurement system in mycotoxins 4. Summary 28

29 2.4 CRM production Core competency Value-Assignment of Calibrant High pure substance Identification analyte in calibrant Purity /calibrant assignment method Sample Analysis Competencies Identification of analytes in sample Extraction of analytes Cleanup - separation of analytes Transformation conversion of analytes Calibration approach for value-assignment of analytes in matrix Verification method for value-assignment of analytes in sample 29

30 Food matrix CRMs in NIM Till Sep. 2016,food related CRM: 451,pure & solution: 391;matrix: 60 Matrix type Measurands pesticide additive 5 68 Pure CRM nutrient hormone packing contact drug 0 42 elements species 8 phthalate clinical

31 Sample 1-chloramphenicol in milk powder Sample preparation Chromato graphy separation MS optimization Quantitation Validation Uncertainty evaluation Value(μg/kg) U(μg/kg)(k=2) < Xiu Qin Li, Qing He Zhang, Hong Mei Li,Analytica Chimica Acta, 807 (2014)

32 CRMs No. Mass fractions U (%) k=2 purity of melamine GBW % 0.5 GBW mg/kg 16 melamine in milk powder GBW mg/kg 14 GBW mg/kg 10 Relative CRMs 32

33 Outline 1. Background 2. Metrological Traceability in Analytical chemistry Concept of metrological traceability Key factors in quality control of measurement Method development CRM production Proficiency test 3. Establishment of the global measurement system in mycotoxins 4. Summary 33

34 2.5 Proficiency test Specially designed inter-laboratory comparisons was combined with external QC activities of field laboratories and promote the establishment and spread of valid national metrological traceability system. Providing customized multi-level blind samples Providing independent reference values Providing technical analysis in aspects of reference materials used, method performance, measurement uncertainties and risk in compliance assessment like false negative or positive results. 34

35 PT on food safety organized by NIM Year Name number of participants 2010 Determination of chloropropanol in soy sauce Determination of benzo[a]pyrene in edible oil Determination of sodium thiocyanate in liquid milk Determination of lead and chromium in solution Determination of lead and chromium in milk powder food safety Determination related of PTs lead cover and chromium 11 food in tea matrix, about Determination kinds of pigments measurands in wine Determination of cadmium in rice Determination of aluminum in vermicelli Determination of 16 kinds of phthalate acid esters in Chinese spirit Determination of aflatoxin in liquid milk Determination of 16 kinds of phthalate acid esters in chinese spirit Determination of lead in infant powder Determination of aflatoxin M1 in milk Determination of clenbuterol in pork Determination of progesterone and methyltestosterone in milk 8 35

36 Multi-targets and sample transfer means Accuracy of the property value of reference materials Preparation capabilities Certification capabilities Lab1 Performance of measurement methods Measurement capability of testing laboratories Lab1 Lab2 Lab3 pilot laboratory pilot laboratory Lab n Lab n Lab2 Lab3 36

37 Primay data analysis Histogram Kernel density Normal distribution test Integrated statistical and technical analysis Regressed value for multi-point comparison Ordinary linear least square method linear regression with errors in both axes Intercept 1 and slope 1 significantly: Big errors in the nominal property values of evaluated RMs Commutability Systematic error Standard deviation estimate Standard deviation estimate of uncertainty weighed mean from expert laboratories Standard deviation estimate of robust median from participants Shortest coverage interval Performance evaluation 4 Method performance Laboratory performance Analytical method dependence Matrix effect and commutability Technical advices % 置信概率 系列 2 99% 置信概率 37

38 Traceability Verification Traceability control Priority in selecting reference value 1. Measured or gravimetric prepared value by pilot laboratory 2. consensus value from collaborative expert laboratories 3. Consensus value from participants 4. Other methods Priority in selecting measurement method 1) national primary apparatus or primary methods; 2) High accurate methods, the accuracy of them has been proved through the international measurement comparisons; 3) reference laboratory system established through inter-laboratory study; 4) high precision methods using PRM or metrological traceable to provide measurement traceability. 38

39 Traceability control CCQM-K24 Cadmium in rice CCQM-P64,K56 Trace elements (calcium, iron, zinc and copper) in whole fat soybean powder CCQM-K59 Nitrite in water CCQM-K103 melamine in milk powder CCQM- K106 Pb, As and Hg in cosmetic material CCQM- K89 Trace and Essential Elements in Herba Ecliptae (As,Ca,Cd,Pb,Zn) Cd in rice with two levels of concentration PT- nutritious elements in whole fat soybean powder Quality evaluation of reference materials :nitrite in water Method performance assessment of rapid testing methods for melamine in milk PT- Hg in cosmetic material with two levels of concentrations PT- Cd,Pb,Cu in white atractylodes rhizome Traceability control International comparison Median: mg/kg NIM value: 0.214mg/kg PT International comparison PT 39

40 Z 比分数 CCQM-K103 & P145 LC-MS-MS GC-HRMS Raman Microscope 奶粉 5(16.3mg/kg) Z 比分数 LC-PDA Melamine in milk powder < Z < 3 7.2% Z < 2 82% Z > % 实验室代码 Melamine in liquid milk and milk powder 40

41 PT -- Aflatoxin M 1 in milk 33 Labs 0.2 μg/kg Reference value Median NIM prepared the PT sample and certified the reference value using LC-IDMS The certified value has good consistency with the medium value 26 of 33 labs got favorable results 41

42 Outline 1. Background 2. Metrological Traceability in Analytical chemistry Concept of metrological traceability Key factors in quality control of measurement Method development CRM production Proficiency test 3. Establishment of the global measurement system in mycotoxins 4. Summary 42

43 3 Establishment of the global measurement system in mycotoxins Laula Anfossi, Recent patents on food, nutrition & agriculture, 2010, 2,

44 3 Establishment of the global measurement system in mycotoxins Purity assessment High accuracy method Standard method Method development CRM Calibration solution Matrix CRM Calibrations:Aflatoxin B1, Zearalenone, Patulin, Deoxynivalenol,etc. Matrix:Cereal, Dairy product, apple juice, oil, nuts, meat Comparison Knowledge transfer, PT Calibration solution Food matrix Secondment Training PT 44

45 Collaboration with BIPM and other metrology institutes, to develop metrological capacity and the metrology infrastructure in mycotoxin: To quantify mycotoxins in food accurately To support standardization in mycotoxin To realize world-wide free trade in food APMP ACRM NIM Regional Metrology Organizations (RMOs)

46 MW Priorities in Mycotoxins Matrix CRM MW vs. Polarity Fumonisim B Ochratoxin A Zearalenone Aflatoxin M1 Deoxynivalenol Aflatoxin B1 Patulin PKow Aflatoxin B1 in oil Polarity: High Polarity(-2 4) Low Polarity(-8-2) Molecular weight: Low MW(0 ~ 300) Medium MW( ) High MW( ) Aflatoxin B1 in peanut Ochratoxin A in meat etc. Ochratoxin A in cereal etc. Fumonisim B in maize etc. Zearalenone in maize etc. Deoxynivalenol in rice flour Aflatoxin M1 in milk powder Patulin in juice Company Logo

47 1. General background Outline 2. Metrological Traceability in Analytical chemistry Concept of metrological traceability Key factors in quality control of measurement Method development CRM production Proficiency test 3. Establishment of the global measurement system in mycotoxins 4. Summary 47

48 4 Summary 1. Delivery service by CRMs and PT from NMIs are the important approach of establishing metrology traceability system 2. The national measurement technical system is established through the international mutual recognition to the core competency achieved by study on features of analytical techniques, typical matrix and the characteristics of analytes. It is the technical insurance of the formulating of standards and laboratory accreditation. 3. High accuracy techniques of chemical metrology could evaluate the accuracy of measurement results of testing as well as ensure their reliability and validity. It is primary importance to the improvement of technical progress of advanced measurement technologies in the field of food safety. 4. The establishment of Metrological Traceability system in Mycotoxin sustains world-wide free trade.

49 Acknowledgement Funded by the Ministry of Science and Technology of China The technical group: Dr. Li Xiaomin, Dr. Zhang Qinghe, Dr. Li Xiuqin, Dr. Lu Xiaohua, Dr. Lu Hai, Mr. Guo Zhen, Dr. Huang Ting,

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