Examples of Method Validation Studies Conducted in Different Economies Template for group discussion National Metrology Laboratory, Malaysia 8th APMP TCQM-DEC MiC Workshop, Kobe, Japan December 2011
Description of Analytical Method Provide details on: Trace and essential elements (As, Ca, Cd, Pb and Zn) Plant based products (Herbs) Concentration rang: As (0.7-2 μg/g) as total Ca (10-30 mg/g) Cd (2-6 μg/g) Pb (3-10 μg/g) Zn (30-80 μg/g) All elementals were analysed by ICP-MS
Choice of Method Made From? Literature methods Provide details AOAC Official methods, Manual (US/FDA)/USEPA In-house development In-house Method Based (Modification of Agilent Technology for metal analysis in plant based products)
Method Validation Requirements List the performance characteristics assessed during method validation, examples are given in the table below - replace them with those relevant to your example Performance Characteristics Instrument calibration function and range Method linearity Accuracy Measurement uncertainty Method detection limit (LOD) Metrological traceability Method quantification limit (LOQ) Repeatability Reproducibility
Instrument Calibration Provide information on the Calibration Materials. Examples are given below, replace them with the calibrants used in your example, state whether you believe they provide traceability to the SI Analyte Supplier Stock Concentration Traceable to SI? Arsenic Trace Cert Fluka Analytical Yes (NIST SRM 83) Calcium LGC Yes (CRM LGC 7162)
Instrument Calibration Analyte Supplier Stock concentration Traceable to SI? Cadmium Lead Zinc Trace Cert Fluka Analytical Trace Cert Fluka Analytical Trace Cert Fluka Analytical Yes (NIST SRM 728) Yes (NIST SRM 728) Yes (NIST SRM 728)
Instrument Calibration Analyte Detector Linear range Calibration function Arsenic ICP-MS 4 200 μg/l Linear model/polynomial Calcium ICP-MS 0-100 mg/l Linear model/polynomial Cadmium ICP-MS 1 50 μg/l Linear model/polynomial Lead ICP-MS 4 200 μg/l Linear model/polynomial Zinc ICP-MS 10 500 μg/l Linear model/polynomial List any considerations related to calibration standards: e.g. solution stability, choice of solvent, storage conditions, matrix calibration samples (assessment of matrix effects), contamination
Sample Treatment Methods Arsenic Calcium Sample Preparation 5 ml HNO3, 1ml H 2 O 2 and using microwave digestion system 5 ml HNO3, 1ml H 2 O 2 and using microwave digestion system Calibration method External calibration (5 points) External calibration (5 points) Cadmium 5 ml HNO3, 1ml H 2 O 2 and using microwave digestion system External calibration (5 points) Lead Zinc 5 ml HNO3, 1ml H 2 O 2 and using microwave digestion system 5 ml HNO3, 1ml H 2 O 2 and using microwave digestion system External calibration (5 points) External calibration (5 points)
Instrumentation Conditions Instrument Model Acquisition Parameters Detector Conditions Acceptance Criteria As 7500cx ICP-MS Agilent Tech Collision mode He Isotope monitored; Mass 75 Resolution Low Cps and based on 0.9999 CC Ca 7500cx ICP-MS Agilent Tech Collision mode He Isotope monitored; Mass 44 Confirmation mass43 Cps and based on 0.9999 CC Resolution Low Cd 7500cx ICP-MS Agilent Tech Collision mode No gas mode Isotopes monitored: mass 111 Confirmation mass 111 Cps and based on 0.9999 CC Resolution: low Pb 7500cx ICP-MS Agilent Tech Collision mode No gas mode Isotope monitored; Mass 208 Resolution Low Cps and based on 0.9999 CC Zn 7500cx ICP-MS Agilent Tech Collision mode He Isotope monitored; Mass 66 Confirmation mass 64 Cps and based on 0.9999 CC Resolution Low
Recovery and Confirmation Recovery, Selectivity, Confirmation of Identity Trace and essential elements ecliptae Absolute recoveries Eg 90-110% Confirmatory Analysis/Interference checking e.g. All analyte were compared against matrix reference materials from GLHK but just limited to certain analytes only.
Method Validation Approach Provide information on the Method Validation Approach used, examples are given below replace them with the information related to your example Precision Method LOD and LOQ Accuracy Approach used ICP-MS, analysis on different days involving different samples to cover a different weiht within a sample type Spiked blank samples at different concentrations, 5 replicate analyses Commercial Certified Reference Materials (CRMs) traceable to NIST
Ongoing Quality Control Aspects Fill in the required details below for how the method would be used routinely. State how many of each type of QC sample would be analysed per batch of samples: Reagent blanks: 1 Method blanks: 1 Spiked samples: 1 Duplicate analysis: 1 per 10 samples CRMs: only for samples close to regulatory limits Other
Measurement Uncertainty Outline your approach to MU estimation For example based on: Bottom up (EURACHEM) PT scheme data In the following table list the components that were combined to estimate the total MU
Example Measurement Uncertainty Table Component Concentration of the calibration material Accuracy Method precision Sample mass, Calibration of balances and volumetric glassware Source of data for uncertainty estimation Certificate of Analysis Spiked samples at a known concentration Assessment of potential bias using confirmatory analysis CRMs Intra-laboratory reproducibility (quality control samples) Calibration certificates
Metrological Traceability Diagram MOLE METRE, KILOGRAM Method Validation Instrument calibration / / Repeatability Reproducibility -intra-laboratory / Calibration Solution - (provide concentration and uncertainty) / / / -inter-laboratory Recovery/spiked samples Ruggedness Confirmation of Identity Selectivity Accuracy/CRMs Linearity LOD, LOQ Test result (state result and MU) / / Pure standard (state manufacturer/certificate details) Volumetric apparatus (state calibration procedure) Gravimetric apparatus (state calibration procedure)
Areas to Address Resource limitations? - Matrix reference materials very difficult to obtain - Limited time What technical difficulties were encountered during method development/validation? - Run-to-run variability test very hard to control - Method validation processes - Demonstrate the metrological traceability Accreditation status: ISO 17025? - Still in the process and updating the quality documents for metal analysis in foods