Validation of ISO/DIS 20244 Soil quality - screening method for water content - determination by refractometry
2018
Vark, van, Winnie | Pellen, Peter | Crum, Steven | Harmsen, Joop
ISO/TC190/Soil Quality has developed a standard to enable measurement of water content in soil and soil-like materials using a screening method ISO/DIS 20244. To become a full standard, the screening method required validation to show the applicability and comparability of the method in different laboratories (repeatability and reproducibility). This validation was organised by WEPAL, (Wageningen Evaluating Programs for Analytical Laboratories), which is part of Wageningen University in the Netherlands. 11 laboratories participated in the validation. Samples with comparable and known water content were distributed. Repeatability and reproducibility were calculated according ISO 5725. The measured water contents were lower than measured with ISO 11465. Probably the sucrose solution is not able to extract all water. Correction of the result using clay content and or organic matter content may be possible, but needs further investigation. The responsible ISO Working Group has to decide if and how the results can be added to ISO/DIS 20244 to become a full standard.
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