Second meeting of the Global Soil Laboratory Network (GLOSOLAN), 28 - 30 November 2018, FAO HQ, Rome, Italy Winnie van Vark, WEPAL

1. Proficiency test
Preparation and execution
Winnie van Vark
WEPAL, Wageningen University

2. Introduction WEPAL
Wageningen Evaluating Programmes for Analytical Laboratories
• PT provider since 1956
• Programmes:
• Soil (metals, nutrients, soil characteristics, avail. Fraction)
• Plant (metals, nutrients)
• Sediments ((an)organic contaminants)
• Organic waste (sewage sludge and compost)
• Biomass (proximate and elementary analysis)
• In 2011 merge with QUASIMEME
• PT provider since 1992
• 30 programmes in water, biota and marine sediments
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3. ISE
International Soil Analytical Exchange
• Started in 1988:
To guarantee homogeneity sample material:
• 1993 Introduction of a sample dividing device
• 1996 Introduction of bulk dividing equipment
• Accredited acc. to ISO/IEC 17043 since 2000
• In 2017
• 365 participants in 85 countries
(800 participants in 5 programmes)
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4. Preparation (Soil-)Samples
• Drying at 40 oC
• Crushing (< 5 mm)
• Grinding (< 0.5 mm)
• Bulk dividing over buckets (homogeneity check)
• Sample diving (items 100 gr) (homogeneity check)
• Barcoding the samples
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5. Drying on air or 40 oC
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6. Crushing and grinding
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7. Dividing (buckets and pots)
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8. Benifits Proficiency Tests
• Set up analytical methods
(Capacity building)
PT Learning Mode (samples with known concentrations)
• Proving experience
(Accreditation)
PT Performance Mode (unknown samples)
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9. PT and Set-up of analytical
capacity
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PT-
performance
mode

10. Learning mode: Do it yourself
• Participate in PT with a large number of
participants
• Compare own results with the group
• Take measures to improve
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11. Learning mode Resolan
• Regional organization of laboratories X
• Regional preparation and distribution of PT-
samples ?
• Regional discussion of results X
• Improvement as individual laboratory
and as group X
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12. Regional distribution of PT-
samples
Regional preparation and organisation
• Advantages
• More easy to prepare “local” samples
• Disadvantage:
• Less participants and
• high uncertainty on the real value of parameters in
distributed sample (example)
• Preparation of homogeneous sample is only feasible for
limited numbers of samples
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13. Results of a regional PT
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14. Results of a regional PT
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15. Learning Mode
• Use samples with known composition
• Certified reference samples
• Expensive (approx. € 300/50g),
• Not available for all Glosolan parameters
• Samples with history in PT
• Cheaper (approx. € 60/100g)
• Available for Glosolan parameters
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16. PT-Performance mode
• Regional distribution
• Limited number of participants
• Uncertainty ‘real’ value
• Global distribution
• Large number of participants
• Higher certainty ‘real’ value
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17. Role Glosolan in PT-Performance
mode
• RESOLANs
• Discuss results
• Further improvement
• New parameters
• Supply regional soils for new parameters
• Glosolan
• Exchange of experience within RESOLANs
• Global issues
• Standardization of methods
• Harmonisation intercomparison and regulatory constrains
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18. Production of PT-samples (1)
• Every laboratory should receive and analyze the
same homogenized material
• Homogeneity is very important and should be
guaranteed
• Different particles: difficult to mix
• Tendency to separate
• Only mixing (e.g. cement mixer) is not sufficient
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19. Production of PT-samples (2)
• WEPAL-equipment is specially developed and
suitable to prepare PT-samples
• Variation in the batch <2%
• Production of large numbers of identical samples (> 10.000)
• Not all materials are suitable (variation > 3.5%)
• Wepal is accredited according ISO 17043
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20. Role of WEPAL
• WEPAL-programme in soil includes GLOSOLAN
programme
• pHwater, pHKCL, EC, OC, TN, available K, available P,
CEC, Exch. Ca, Exch. Mg, Exch. K, Exch. Na, Exch. acidity,
Texture
Other parameters can easily be added
• Learning-mode
• Provide samples with known composition
• Collect and report data with existing system (internet)
• Prepare new samples
• Performance mode
• Participations of Glosolan members in WEPAL program
• (4 times 4 samples/year)
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21. Problems to be solved
• How to finance?
• Role FAO
• Other international organisations
• GO’s and NGO’s.
• Custom demands
• One global valid form?
• Role FAO
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• Sanitary certificate
• Certificate of domicile
• Certificate of origin
• Commercial invoice
• Sample definition
• Safety data sheet
• WEPAL statement: goal PT
• Etc.