philippe quevauviller - metrology in environmental chimistry 1 metrology in environmental chemistry...

Philippe Quevauviller - Metrology in environmental chimistry

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METROLOGY IN ENVIRONMENTAL CHEMISTRY

Philippe QUEVAUVILLER

Centre of Excellence on Environmental Analysis and MonitoringGdansk, 21st April 2005


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CONTENT OF THE COURSE

GENERALITIES- Chemical Metrology -

- Quality assurance -- Environment monitoring -

- Regulations -

SCIENTIFIC AND TECHNICAL FRAMEWORK- Methods: selection and validation -

- Tools for quality: Reference materials -- Interlaboratory studies -

- Examples of European projects -

PERSPECTIVES- Monitoring -- Data quality -

- Research -- Training -


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METROLOGY- Generalities -

The metrology is the science of measurements

System covering basic concepts such as traceability, uncertainty, calibration,validation, etc. of measurements - It must guarantee that analytical data are:

(1) expressed according to recognised units, in principle units of the “Système International” (SI)

(2) comparable between laboratories and over time

(3) provided to the user(s) with clear information regarding their significance (uncertainty)


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METROLOGY- Units of the “Système international (SI)”

-

• Metric system established in France during the French revolution (standard metre conserved at BIPM in Sèvres since 1889)

• At the Conférence Générale des Poids et Mesures (CGPM) in 1901: the kilogramme is declared mass unit, sorting out the the ambiguity between « weight » and « mass »

•Time: The SI unit is the atomic second (since 1968), corresponding to the radiation between two levels of the basic state of the 133cesium atom

• Temperature: centigrade or Celsius scale (freezing or boiling points of pure water established at 0 and 100 °C - Kelvin scale (absolute zero at approx. -273 °C)

• Mole: mass of substance, measured in reference to the kilogramme (mass of 12 g of 12carbon = one mole of carbon) - This unit links the atomic/molecular entity of the matter to

a macroscopic scale, through classical chemical reactions• Derived units: for example, surface, density, pressure, viscosity, etc., the most used

being the volume (defining the litre as « a volume occupied by the mass of 1 kg pure water at its maximal density, at a standard atmospheric pressured »)


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METROLOGY- Some definitions (1) -

• Trueness: « closeness of agreement between the result of a measurement and the true value of the measured value. The true value is the value that would be obtained by the measurement if the amount could be perfectly determined

and all the errors eliminated »

•Precision : « closeness of agreement between the results of a series of repetitions of analyses of a substance in a single sample. This term is usually separated into repeatability (same instrument, analyst, location, conditions of

utilisation, and short-term period of time) and reproducibility (variations of conditions, methods, analyst, location). The data related to precision are generally expressed in the form of standard deviations or, more often, of coefficients of variation of the mean of results of the measurement series. This should be distinguished from the robustness, which corresponds to the capacity of the method to remain unaffected by minor changes of the procedure (e.g. reagents or

environment) »


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• Specificity: « response of a single analyte, not affected by possible interferences »

• Sensitivity: « minimal significant variation of a measurement result »

•Linearity: « capacity of obtaining, in a given interval, results that are directly proportional to the analyte concentration »

• Limit of detection : « smallest quantity of analyte that may be detected but not quantified (the detection limit is closely linked to sensitivity and to the stability of the analytical system »

• Limit of determination : « expression of the smallest amount of analyte which may be quantified - This limit is generally taken as being equivalent to 5 to 10 times the detection limit »


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Traceability : « property of a measurement result or the value of a standard to be linked to established references, generally national or international standards, through an unbroken chain of comparisons, each having an established

uncertainty »

The comparabilitu of the results is the primary condition - The traceability is a tool, which should permit to achieve this comparability.

The references may be SI units, calibrants, reference materials, (written) standards, reference methods - The unbroken chain of comparisons implies that links are established between the various analytical steps of the method used - The

uncertainty should in principle be calculated at each step and combined (total uncertainty), which is not always achievable in practice.

Possible « hierarchy » of links: SI Units (e.g. kg, mole) - international transfer standards (ex. kg) - atomic masses -pure calibrants of chemical substances - primary methods - Primary (matrix) reference materials - Secondary

reference materials - Routine methods and Laboratory reference materials


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CHEMICAL METROLOGY- Specific aspects -

Influence of sample matrix

Variety of analytical problems in relation to the millions of substances and thousands of sample types

Need of preliminary operations before the analysis (sampling, storage etc.) and related problems (e.g. stability, homogeneity of samples)

Needs of tools for the quality control of measurements (e.g. « matrix » reference materials)

Specific needs for the validation of methods including various steps

Difficulties for demonstrating the traceability of results and calculating the total uncertainty


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QUALITY ASSURANCE- Chemical analyses -

DEFINITIONS

Quality: « Characteristics of a product or a service which conferthe aptitude to satisfy the implicit or expressed needs »

Quality assurance : « Preestablished and systematic actions necessary to provide the appropriate confidence that a product or service will satisfy given requirements related to quality »

Quality Control : « Techniques and operational activities that are used to respond to respond to quality requirements. It implies activities that both aim to follow a process and to eliminate the causes of failure

with the view of achieving the best economic efficiency »

Quality system: « Organisational structure, covering the responsibilities, procedures andprocesses, to implement the quality activities (determining the quality policy of an enterprise) »


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QUALITY ASSURANCE- User’s needs -

The results have to be fit to the purpose for the study, as well as the means that are used (the highest level of accuracy is not systematically required)

Example: Considering the guide value of arsenic in contaminated soils = 40 mg.kg -1

A soil will be considered as contaminated is an analytical result exceeds this guide value.If the As content is below 10 mg.kg-1, an absolute trueness is not necessary, and it is only necessary to define the confidence level of the results. The problem will be different if the content is 39 mg.kg -1 or 41 mg.kg-1

A well informed customer will ask (1) if the method is appropriate, (2) if it has been validated, (3) what are the sources of uncertainty and (4) what is the

confidence level that can be expected from the results. The quality/price ratio of the analyses will also be considered.


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QUALITY ASSURANCE- Implications -

FOOSTUFFS- Detection of toxic risks -

- Nutrition -

ENVIRONMENT- Evaluation of environmental risks -

- Detection of pollution -- Biogeochemical studies -

BIOMEDICAL ANALYSES- Diagnosis -

- Biochemical research -- Forensic science -

INDUSTRY- Product quality -


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CONSEQUENCESOF ANALYTICAL ERRORS

DECISIONS

Food toxicity(e.g.. dioxins)

Environmentalpollution

(e.g. drinking water)

Medical diagnosis,forensic science

Industrial products(e.g. impact on trade)


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ANALYTICAL ERRORS- Example -

Dioxins in fly ashes

« There is no democracy in science »

A statistical analysis enables one to study the distribution of a populationof data but it cannot explain the differences between results


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Dioxins in fly ashes

Mean standard deviation

Time

F118

F119

F121

F130

45 : 00 50 : 00 55 : 00

Lab. 5

(a) Column used for the first time (lab. 5)

F118(+F119)

F121 F130

( b) Other columns or old DB Dioxin

The majority of the laboratories (b) found a value for F118 (hexaclorodibenzofuran) which was 20 % too high. Only the laboratory 5 was right.


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ANALYTICAL ERRORS- Example -

Heavy metals in lichenBCR (1992)

ElementLowest value

(mg/kg)[Method]

Highest value(mg/kg)

[Method]Ratio

ZnCuHg

9.7 [AAS]0.8 [AAS]

0.005 [CVAAS]

283 [ICP]39 [ICP]

0.551 [CVAAS]

2948

110

Within the two years preceeding this study, around 2000 papers had been published in lichenology.The results of these studies have been used to evaluate the atmospheric contamination

and to take “appropriate” decisions …...


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ENVIRONMENT MONITORING- General principles -

PRINCIPLES- Definition of the problem (regulations, research?) -

- Choice of a strategy -- Chemical and/or biological analyses -

- Interpretation and decision -

PARAMETERS- Media, types of samples analysed -

(e.g.. Contaminated soils, sediments, waters, biological samples, etc.)- Substances (regulated or not) -

(e.g. heavy metals, nutrients, chemical species of element, organic compounds)

OPERATIONS- Sampling -

- Treatment / Storage of samples -- Analysis -

- Presentation of the data -


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ENVIRONMENTMONITORING

- Matrix types (1) -

WATERSgroundwater, lake waters, rivers, estuaries, seawater, rainwater, wastewater - direct analyses,

pretreatment in some cases (e.g. for waters rich in organic matters)

SEDIMENTSContaminants « sinks » (contamination history). Matrices of variable compositions,

numerous interfering substances, difficulties to obtain a complete recovery of the analytes. Analyses requiring pretreatment steps, followed by various steps (e.g. separation)

SOILS, SLUDGES, COMPOSTSAgronomy studies, risk assessment, monitoring of treatment efficiencies, etc.

Similar difficulties in comparison to sediments, but more acute owing to a greater heterogeneity.


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- Matrix types (2) -

BIOLOGICAL SAMPLESPlants, biological organisms (e.g. molluscs) analysed for bioaccumulation capacity

and used as « indicators » (trend studies, indicators of the quality of an ecosystem, nutritionalstudies, etc.). Complex matrices that include various types of components (carbon, fat

mineral particles, dusts).

ATMOSPHERIC SAMPLESAir, dusts, fly ashes, etc. Direct analyses using sensors (air) or indirect

(e.g. sampling on filters, leaching and « classical » analysis). Some bioindicators are usedfor the indirect monitoring of atmospheric contamination (e.g. lichens)

VARIOUS WASTESOf domestic or industrial origin. Analyses often based on leaching tests

to determine the « mobile » fraction of contaminants


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- Parameters (1) -

PHYSICO-CHEMICALpH, turbidity, conductivity, redox potential, etc.

MAJOR ELEMENTSMatrix elements, contents above 0.1% in the environment

Examples: Si, Ca, K, P, Mg, Mn, N, Na, Fe

TRACE ELEMENTSContents at the mg/kg or µg/kg level - Ultratraces levels being less than µg/kg

Toxic and/or essential elementsExamples: As, Ba, B, Br, Cd, Cr, Co, Cu, F, I, Hg, Mo, Ni, Pb, Sb, Se, V, Zn


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- Parameters (2) -

CHEMICAL FORMS OF ELEMENTSSpecific forms of elements (e.g. different oxidation states, organometallic compounds,

oxides or hydroxides, complexed forms)Examples: As(III), Cr(VI), methylmercury, tributyltin

« EXTRACTABLES » CHEMICAL FORMSChemical forms of elements that are operationally defined (single or sequential extraction)

They are qualified, e.g. as « mobile », « bioavailable », etc. forms

ORGANIC COMPOUNDSOf anthropogenic origin or products of organic decompositions

Examples: chlorophenols, dioxins, hydrocarbons, pesticides, herbicides, polychlorobiphenyls


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- Types of methods (1) -CALCULABLE METHODS

Result which may be foreseen from a calculation made on the basis of physical or chemical measurements such as, e.g., sample weighing , volume of titrating reagent, etc. (e.g. titrimetry, gravimetry,etc.)

PRIMARY (OR DEFINITIVE) METHODMethod with the highest metrological quality, having few random errors

(and no systematic errors), and for which a complete estimate of theuncertainty may be obtained in terms of SI units (e.g. titrimetry, IDMS)

RELATIVE METHODSComparison of the analysed sample with calibrants of known concentrations. The result

is established through interpolation with the response curve of the calibrants (e.g. spectrometric techniques)

COMPARATIVE METHODSComparison of the analysed sample with calibrating samples which have not been subject to any

chemical treatment. The calibration is performed using certified reference materials witha matrix similar to that of the sample (e.g. X-ray Fluorescence spectrometry)


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- Critical points (1) -

GENERAL FRAMEWORK

Selection of suitable method(s)(sampling, analysis, storage)

Quality assurance(validation, quality control)

Long-term storage(specimen banking)


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- Critical points (2) -

SOME SELECTION CRITERIA

SAMPLINGRepresentativeness of the

environment, type of sample,(selective, random of composed),

sampling strategy (site, frequency, procedure, etc.)

CONSERVATION / STORAGEPreservation of the integrity(transport conditions and

conservation / storage,types of containers, temperature, etc.)

ANALYTICAL METHODSEquipment (e.g. glassware), and

consumables (e.g. reagents ofknown purity), maintenance,

costs and adaptation to the aimof the analyses


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SELECTION OF METHODS FORENVIRONMENTAL MONITORING (1)

Criteria- Selectivity, sensitivity, trueness -- Repeatability, reproducibility -

- Detector linearity -- Robustness -

- Costs (purchase, maintenance) -- Facility and speed of utilisation -

“COUPLED” METHODS• Extraction (acids, organic solvents)

• Derivatisation (hydride generation, Grignard reactions)• Separation (GC, HPLC)

• Detection (AAS, ICP-MS, ECD, MS, etc.)


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Sampling« avoiding any risk of contamination or losses »

WATERS- PTFE, polyethylene, polypropylene, borosilicate glass, etc. -

SEDIMENTS / SOILS, BIOTA- Plastic tools or PTFE -

Pre-treatment

WATERS- Acidification, filtration -

SEDIMENTS- Sieving (wet, using water from the site) -


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Stabilisation / Long-term storage (examples)« Preserve the initial geo- and biochemical status »

STABILISATION- Acidification (waters) -

- Lyophilisation (biota, sediments, etc.) -- Oven-drying (sediments) -

- Pasteurisation (sediments) -- Gamma irradiation (biota, sediments, waters) -

STORAGE- Freezing for “sensitive” compounds (biota, sediments) -

- Storage at ambient temperature or at 4 °C (in the dark) -


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Extraction / Digestion (examples)ACIDS

Acetic acid, sulphuric acid, nitric acid (e.g. with microwave), hydrofluoric acid (total digestion), etc.

MIXTURE ACID / ORGANIC SOLVENTHydrochloric acid/toluene, sulphuric acid/toluene, etc.

ORGANIC SOLVENTSToluene, methanol, tropolone

pentane, etc.

RECOVERY TEST: Spiking (three levels)

OTHERSCO2 / methanol, supercritical fluid

enzymatic digestion (protease/lipase), etc.


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Derivatisation (examples)« Transformation of a given compound

for a better separation »

Hydride generation (NaBH4)Ethylation (NaBEt4)Grignard reactions

VERIFICATION OF YIELDS(secondary calibrants)


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SELECTION OF METHODS FORENVIRONMENTAL MONITORING (6a)

Separation (examples)« required owing to the fact the determination of different

compounds of a same ‘family’ cannot, in general, be carried out with a sufficient selectivity (e.g. selective detection by AAS) »

GAZ CHROMATOGRAPHY- with packed column -

- with capillary column -

HIGH PERFORMANCELIQUID CHROMATOGRAPHY (HPLC)

OTHERS- Cryogenic trapping -

- Capillary electrophoresis -- Ion exchange microcolumns -


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SELECTION OF METHODS FORENVIRONMENTAL MONITORING (6b)

Examples of chromatograms

1 2

3

4

1

23

4

Retention time (minutes)13.9 16.9 11.2 11.4 12.0

A B

Peakheight

A - Megabore column B - Capillary column1. Ph2SnPe2; 2. Cy2SnPe2; 3. Ph3SnPe; 4. Cy3SnPe


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Detection (examples)SPECIFIC OF A GIVEN ELEMENT

- Atomic absorption spectrometry -(electrothermal, flame, quartz furnace)

MULTI-ELEMENT- Inductively coupled plasma atomic emission spectrometry (ICP-AES) -

- ICP mass spectrometry (ICP-MS) -

SPECIFIC OF A GIVEN ELEMENT SPECIES- Voltametry -

SPECIFIC OF A GIVEN COMPOUND- Flame ionisation detection (FID) -

- Flame photometric detection (FPD) -- Electron capture detection (ECD) -


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Calibration

AVAILABILITY OF CALIBRANTS- Primary calibrants (calibration) -

- Internal standards (*) -(correction of matrix interférences, with associated risks, e.g. different response , linearity)

- Stoichiometry, purity -

CALIBRATION METHODS- External -

- Matrix matching -- Bracketing calibration -

- Standard additions -

(*) The term « standard » is often prone to confusion (calibrants, RM, written standards)


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Uncertainty

« Parameter associated to the result of an analysis, characterising the dispersionof the values which may be attributed to the measurement » : Range of values

in which the measured amount should be foundThe uncertainty defines the degree of confidence which may be attributed to a measurement. It includes both systematic effects (errors that are constant or varying in a foreseable way, which may be corrected,

e.g. blanks, incomplete extraction, etc.) and random effects (not controlled, e.g. background noise).

IMPLICATIONS FOR ENVIRONMENTAL ANALYSESThe “total” uncertainty should in principle combine the uncertainties

of each analytical step- Sampling -

- Pre-treatment (extraction, derivatisation) -- Separation and detection -

- Calibration -


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Example : Tributyltin (TBT) in coastal waters

PRESENT AT THE ULTRA-TRACE LEVEL (ng.L-1)Hence need of a sensitive method

OCCURRENCE NUMEROUS ORGANOTIN COMPOUNDSHence need for a selective method

RISKS OF DEGRADATION OF TBTParticular care at the sampling and storage steps.

Need to determine degradation products (DBT, MBT)

ANALYTICAL PROCEDUREObviously a sophisticated technique, combining an efficient extraction

(but not destructive), a good separation and a sensitive detection. Alternative: Bioindicators (e.g. Nucella lapilus)


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PERFORMING ANALYTICAL WORK

General aspects

• Obtaining samples and conserve them in the best conditions• Selecting the method and ensuring that it is in good functioning order

• Planning the work and identifying critical steps (including risks)• Ensuring that a suitable working space is available

• Verifying glassware, consumables, calibrants and RMs• Foreseeing procedures related to wastes (e.g. used solvents)

• Cleaning of the laboratory

NOTE: The analytical report and data archiving is considered as being an integral part of the metrological system. The report should contain a detailed description of the objective of the study, of the procedures used, quality control, performances of the method, the interpretation of the data, questions and unsolved

problems. The archiving should in principle be in electronic form (e.g. use of LIMS software).


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QUALITY CONTROL (1)

Validation(principles)

« Demonstrating that the results obtainedwith a given method are reliable,

reproducible and that the method isadapted to the foreseen application »

• Apparatus, computers• Analytical method (following slides)

• Control charts

S1

S2

M

Synthetic solutions(known calibrants)

Solutions with knownanalyte concentrations and

unknown matrix(e.g. spiked extract)

“Matrix” materialsimilar to the sample(natural or spiked)

Signalcalibration

Purificationseparation

Extractiondigestion


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QUALITY CONTROL (2)

Verification of trueness« Closeness of agreement between the result of a measurement and

the true value of the measured value (the true value is known only is the measured amount may be perfectly determined and if all the

measurement errors have been eliminated »

Verification of precision« Closeness of agreement between results of measurement of a

same substance, applying the same experimental procedure several times in the same conditions (repeteability; the

reproducibility is the closeness of agreement in time, taking into consideration variations of conditions (location, analyst); it has to be distinguished from robustness (capacity of the method to

remain unaffected by minor changes of the procedure (e.g. reagents or environment) »

******

* ** *

**

*

*

*

**

**

*

*

**

******

*


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QUALITY CONTROL (3)

Reference Material« Material or substance one or more of whose property

values are sufficiently homogeneous and well established to be used for the calibration of an apparatus, the

assessment of a measurement method, or for assigning values to materials (ISO, guide 30) »

Certified Reference Material« Reference material, accompanied by a certificate, one or more

of whose property values are certified by a procedure whichestablishes traceability to an accurate realisation of the unit in whichthe property values are expressed, and for which each certified value

is accompanied by an uncertainty at a stated level of confidence(ISO, guide 30) »


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QUALITY CONTROL (4)

Control charts« Graphical mean to evaluate

the reproducibility of a method »

SIMPLE CHARTSThe value reported on the chart is the result

obtained each time a measurement is carried out.(see following example)

CUMULATIVE CHART (CUSUMThe value reported on the chart is the sum

of the absolute value of the differences between themeasured value and a reference value.

This type of chart enables to detect more rapidlypossible method drifts.


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QUALITY CONTROL (4 ’)

Example of control chart

Measuredconcentration

mean

2 s

3 s

Warning (2 s) and action (3 s) limits correspond, respectively, to a risk of 1 and 5 % that the result does not belong to thepopulation of other results. The values of the mean and standard deviation (s) are determined by several measurements

(at least 10 repetitions) carried out at the start of the analytical work, but on several days.


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QUALITY CONTROL (5)

Interlaboratory testing

« Study in the framework of which several laboratoriesanalyse one or several identical and homogeneous material(s),

in specified conditionsand for which the results are collected in a single report »


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INTERLABORATORY TESTING (1)

Generalities

TYPES OF STUDIES• Method performance studies

• Proficiency testing schemes (several methods)• Certification of reference materials (attribution of « true values »)

REQUIREMENTS• Co-ordination

• Motivation of laboratories (and competence)• Availability of testing materials

• Technical evaluation of the results• Statistical evaluation


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INTERLABORATORY TESTING (2)

Improving schemes(method performance studies)

The followed principle is similar to a method validation, i.e. analyses of increasingly complex

matrices to detect errors that may occurat various analytical steps.

These schemes have a pedagogical aim andimply the organisation of technical meetings

in the framework of which participants exchangetheir experience and discuss weak points

of the methods and the error sources.

S1

S2

M1

M2

Simple solutions(pure substances

or mixtures of substances)

Matrix-matching solutionsor extracts (spiked or not)

Reference material(« matrix ») similar

to the sample, spiked with aknown analyte concentration

Matrix material similar to the sample

DETECTIONDERIVATISATION

PURIFICATIONSEPARATION

EXTRACTIONMINERALISATION

OVERALLMETHOD


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REFERENCE MATERIALS

Conditions

RepresentativenessIt implies a similarity of composition between the material and the sample that is routinely analysed (similar sources of errors):

• Matrix composition• Contents of substances

• Binding status of the substances in the matrix• Physical status of the material

Homogeneity / stability- Intra- and inter-vial homogeneity -

- Long-term stability -

Setting reference values- « Definitive » method in a specialised laboratory -

- Several independent methods in an expert laboratory -- Several methods applied by several laboratories -


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EXAMPLE OF IMPROVEMENT SCHEME (Methylmercury)

WORK PROGRAMME• Improvement scheme (series of 3 rounds): 1988-90• Certification of fish reference materials: 1991-94

• Certification of sediment reference material: 1994-96

RESULTS• Withdrawal of packed columns

• Detection of sources of errors (e.g. distillation)• Two fish CRMs

• One sediment CRM

Enriched extract

Raw extract

YOUDEN PLOT

mg/kg MeHgMeanof means


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EXAMPLE OF CERTIFICATION RESULTS (Methylmercury)

CONCLUSIONS• Creation of a network of laboratories

• Enhanced knowledge on methods and validation needs• Tools for quality control

PERSPECTIVES- Development of new methods -

(more rapid and easy to use)- Studies of analytical artefacts -

- Laboratory reference materials -

M

75.0 85.065.0

GC-CVAFSGC-CVAAS

GC-CVAAS

GC-QFAAS

GC-ECD

GC-ECDGC-ECD

SFEGC-MIP

HPLC-CVAAS

HPLC-CVAFS

HPLC-ICPMS

MeHg (sediment)in µg/kg


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PERSPECTIVES (1)

- Monitoring -

- Quality (and metrology)-

- Research -

- Training -


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PERSPECTIVES (2)

Environment monitoringTowards a global approach

HARMONISATION- of strategies -

- of methods (from sampling to analysis) -- of “target” parameters and matrices -

- Selection de reference sites (at national / international level) -

“MEMORY”- Storage of environmental specimens -

(specimen banking)- Warning system at the international level -


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PERSPECTIVES (3)

Quality assurance

STANDARDISATION?- Necessary for monitoring strategies -

- Not systematic for analytical methods (risk of “progress fossilisation”) -

ACCREDITATION?- Necessary for control laboratories -

- Necessary for RM producers -

REFERENCE MATERIALS- Establishment of a producer network in Europe -

- Feasibility studies and CRM production -- Structure production of control MRs -

PROFICIENCY TESTING- Organisation of targeted ring tests at international level -

- Support to the accreditation of control laboratories -


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PERSPECTIVES (4)

Metrology

TRACEABILITYAvoiding “fundamentalism” - The demonstration of

traceability of a measurement should remain accessibleto routine laboratories

- Systematic studies of risks of error related to sampling -- “Matrix” materials enriched with isotopically-labelled compounds -

- “Secondary” standards -- Recovery studies on extraction and derivatisation -

UNCERTAINTY- Systematic study on “total uncertainty budgets” -(uncertainty calculated at each step and combined)

- Studies of simplified alternatives for routine uncertainty calculations -


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EXAMPLE OF TRACEABILITY CHAIN(Trace elements in seawater)

RESULTS

CHEMICALTREATMENT

PRETREATMENT,STORAGE

SAMPLING

IDMSDETECTION

ANALYTICAL STEPS

Addition of spike ofknown purity and

stoichiometry

Internationallyrecognisedprocedures

Internationallyrecognisedprocedures

Measurementsof spike ratios

REFERENCES

A

B

C

D


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EXAMPLE OF TRACEABILITY CHAIN(Tribultin in harbour dredges)

RESULTS

EXTRACTION

STORAGE,PROCESSING

SAMPLING

DERIVATISATION(if necessary)

ANALYTICAL STEPS

No standards,available CRMs

No standards,literature-based

No standards,literature-based

Secondary standards

REFERENCES

SEPARATION Internal standards

FINALDETECTION

Primary calibrants

A

B

C

D

E

F


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Extraction,digestion etc.

Written standards,matrix CRMs

Chemical reactions(e.g. derivatisation)

Secondarystandards

SeparationInternal

standards

DetectionPrimary

calibrants

Control charts,proficiency

testing

Routinelyoperated

method(s)

RESULTS

LRMs(freeze-dried)

STORAGE,PROCESSING

SAMPLING

REFERENCE SITES

IRMs(fresh)

Validatedwritten standards

Harmonisedwritten standards

SPECIMENS BANKING

FOLLOW-UP OFENVIRONMENT

QUALITY

INTERNATIONAL

NETWORK

VALIDATED METHOD

Methodoptimisation

Developmentof new methods

Research/testing

to improve fieldmethods and sampling

procedures

A

B C

D1 D2

D3 E

F

G H

I

J


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PERSPECTIVES (5)

Research

ENVIRONMENTAL STUDIES- Biogeochemical cycle of elements and compounds -

- Toxicity and bioavailability studies -- Development of new methods -

(in particular rapid methods, low cost, applicable to the field)

FEASABILITY STUDIES- Research on reference materials -

(e.g. wet materials)- Stability studies of materials / substances -

APPLICABILITY- Interface “science-policy” -

- Public awareness -


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PERSPECTIVES (6)

Training

ENVIRONMENTAL SCIENCESMulidisciplinary training- Geochemistry, biology -- Analytical chemistry -

- Metrology (including quality assurance) -- Regulations (“science-policy” interface) -

QUALITY ASSURANCETheoretical and applied training

- Quality of environmental measurements -(from sampling to decision-making)

- Practical training on site -


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CONCLUSIONS

EUROPEAN NETWORKS- Networked site monitoring (harmonised strategies) -

- International meetings held at regular intervals -(involving scientists, industrialists, regulators)

EXCHANGES / TRAINING- Transfer of knowledge and technologies -- Exchanges of students and technicians -

- International hosting institutions -

CENTRES OF COMPETENCE (National / Regional)- Multidisciplinary expertise in the environmental field -

- Site monitoring -- Environmental specimen banking -


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FURTHER INFORMATION

REFERENCE MATERIALS- CRMs and interlaboratory studies for environmental analysis (1999) -

(Quevauviller & Maier, Elsevier, ISBN 0-444-82389-1)- ISO/REMCO (Laboratoire National d ’Essais) -

- Matériaux de référence pour l ’environnement (Tec&Doc, 2002) -

ACTIVITIES OF THE EUROPEAN COMMISSION- Institute for Reference Materials and Measurements (IRMM) -

(http://www.irmm.jrc.be/mrm.html)- Various general and targeted publications -(contact: [email protected])

ENVIRONMENTAL METROLOGY- Métrologie en chimie de l ’environnement (Tec&Doc, 2000) -

- Metrology in chemistry - A practical approach (Valcárcel et al., 1998) -

philippe quevauviller - metrology in environmental chimistry 1 metrology in environmental chemistry...

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