Challenges for Reliable Measurements across the Boundaries Physics-Chemistry-Biology

Transcription

1 HE / JRC-IRMM, Washington DC, 18 February 2011 AAAS Annual Meeting 1 Challenges for Reliable Measurements across the Boundaries Physics-Chemistry-Biology Hendrik Emons European Commission, Joint Research Centre (JRC) Institute for Reference Materials and Measurements (IRMM)

2 Setting the scene HE / JRC-IRMM, Washington DC, 18 February 2011 AAAS Annual Meeting 2 Health & Quality of life Global trade Compliance with Legislation Reliable Measurement Data Targeted Information Sound Knowledge Qualified Decision Reliability (accuracy) x x x xxx xx xxxx x in time between labs Comparability: x x x x x x xx x x x xx

3 What to measure? HE / JRC-IRMM, Washington DC, 18 February 2011 AAAS Annual Meeting 3 Engineered nanoparticles D Complex molecules (functions) whole molecule? (identity, number ) D 3 D 1 D 2 activity/reactivity part(s) of the molecule? (identity ) non- GMO + foreign DNA Prom. Gene Term. GMO

4 Which parameter? HE / JRC-IRMM, Washington DC, 18 February 2011 AAAS Annual Meeting 4 Diameter? Mass? Activity/reactivity? 3D morphology? Number? Ratio? Definition of decision-relevant measurand - targeted property structural, functional, other? Temporary approach in Physics Chemistry - Biology: Measurands defined by the measurement procedure

5 Nanoparticle size HE / JRC-IRMM, Washington DC, 18 February 2011 AAAS Annual Meeting 5 Dynamic Light Scattering 19.0 ± 0.6 nm ISO Hydrodynamic diameter EHS-(decision) relevant parameter? Centrifugal liquid sedimentation 20.1 ± 1.3 nm Stokes diameter ISO Small angle X-ray scattering from Guinier radius of gyration 21.8 ± 0.7 nm and: particles unstable & reactive transformations & dynamics

6 C-reactive protein HE / JRC-IRMM, Washington DC, 18 February 2011 AAAS Annual Meeting 6 Clinical marker of inflammation Marker of cardiac risk CRP Normalized relative CRP mass concentration by with different immunoassays IA-1 IA-2 IA-3 IA-4 IA-5 IA-6 IA-7 Pentamer in serum 100 % 89 % 107 % 100 % 89 % 98 % 100 % Pentamer in buffer 103 % 49 % 59 % 79 % 96 % 117 % 100 % Standardisation required!

7 GMO quantification HE / JRC-IRMM, Washington DC, 18 February 2011 AAAS Annual Meeting 7 How to determine & report the genetically modified content of feed / food? Mass fraction DNA copy number ratio = number fraction GMO species mass total species mass? copies of transgenic DNA copies of species-specific DNA How to calibrate the (PCR) measurements?

8 DNA copy number ratio HE / JRC-IRMM, Washington DC, 18 February 2011 AAAS Annual Meeting 8 Maize NK603 NK603 content [cp/cp % s] NK603 content [cp/cp %] % (m/m) NK603 maize pdna A B C A B Extraction method gdna C 1.17 % ± 0.21 % using gdna for calibration Soybean % ± 0.19 % using pdna for calibration

9 Towards Comparability HE / JRC-IRMM, Washington DC, 18 February 2011 AAAS Annual Meeting 9 Approach: Standardisation harmonized methods PASC CEN AIDMO EASC Legislation Prescribed methods/procedures COPANT establish/realize measuring scales ARSO PASC ACCSQ PASC MO/LDE9606B.CDR Improving knowledge on structure-property relations Prescribed method-performance characteristics kg (mol, IU, ) material standards required

10 Metrological Traceability HE / JRC-IRMM, Washington DC, 18 February 2011 AAAS Annual Meeting 10 SI standard International standard Reference Material = anchor point National mass standard Local Mass standard calibrating a balance Laboratory calibration standard (Bio)chemical analysis involving methoddefined steps Measurement result GMO content?

11 Traceability anchor HE / JRC-IRMM, Washington DC, 18 February 2011 AAAS Annual Meeting 11 Non-destructive measurements Destructive measurements Artefacts Certified Reference Material Reference standard Reference substance Calibrant / Calibrator Standard material Analytical standard Challenge: sustainable primary standard homogeneous subsamples appropriate stability metrologically valid property value with small uncertainty

12 Metrology & Standardisation HE / JRC-IRMM, Washington DC, 18 February 2011 AAAS Annual Meeting 12 Across borders solution for operationally defined measurands Parameter ( quantity ) definition Reference Methods e.g., particle size as measured by DLS ISO method GM content as measured by PCR method C-reactive protein in human serum via method Reference Material Reference Laboratories Traceability anchor Reference Measurement System

13 RMS for GM quantification HE / JRC-IRMM, Washington DC, 18 February 2011 AAAS Annual Meeting 13 for measurements of GM DNA copy number ratio by quantitative PCR Plasmid Transgenic DNA sequence (1) 1:1 ratio Speciesspecific DNA sequence (1) pdna CRM Independent calibration Food/feed sample Sample preparation DNA extraction / purification Real-time PCR Data evaluation Measurement result Also: highest order CRMs for human proteins (chemistry), impact toughness of steel (physics), etc.

14 Uncertainty of decisions HE / JRC-IRMM, Washington DC, 18 February 2011 AAAS Annual Meeting 14 Measurement result: _ x ± U threshold Challenges: (1B) (1A) (2A) (3A) adequate estimation of U by each lab (4A) (4B) harmonized application of U Problem Measurand definition Sampling Measurement Data evaluation Measurement result

15 Take-home messages HE / JRC-IRMM, Washington DC, 18 February 2011 AAAS Annual Meeting 15 Across scientific & regulatory & geographical borders: identify & specify the relevant measurands develop & agree on adequate reference measurement procedures for functional properties, sum parameters etc. combine documentary with material standards for ensuring comparable results of emerging measurement tasks design & realize globally accepted anchor points for sustainable metrological traceability tackle the scientific challenges for establishing & qualifying highest order reference materials exploit knowledge & progress of various scientific disciplines for general measurement solutions and uncertainty estimations

16 Final conclusion HE / JRC-IRMM, Washington DC, 18 February 2011 AAAS Annual Meeting 16 You may think you know a subject, but until you can measure it and calculate it your knowledge is of a vague and unsatisfactory kind Ernest Rutherford ( )