Inter-laboratory validation of an ISO test method for measuring enzyme activities in soil samples using colorimetric...

Area of Science:

• Soil Science
• Biochemistry
• Environmental Science

Background:

• Soil quality assessment relies on biological indicators, particularly enzyme activities.
• Existing enzyme activity measurement methods need updating for routine use, balancing feasibility, accuracy, and reliability.

Purpose of the Study:

• To optimize and validate a miniaturized micro-well plate method for measuring soil enzyme activities.
• To standardize this method for routine soil quality assessment and potential ISO certification.

Main Methods:

• A miniaturized colorimetric method using micro-well plates was optimized by the Biochem-Env platform.
• An inter-laboratory validation study was conducted involving eight laboratories measuring ten soil enzyme activities across six contrasting soil types.
• Repeatability (intra-laboratory CVr) and reproducibility (inter-laboratory CVR) were calculated.

Main Results:

• The method demonstrated high repeatability (mean CVr 4.5%–9.9%) and reproducibility (mean CVR 13.8%–30.9%).
• Outlier identification was minimal (2.7%), indicating robust data.
• The method proved sensitive, repeatable, reproducible, and applicable across diverse soil types.

Conclusions:

• The optimized miniaturized method is suitable for routine measurement of soil enzyme activities.
• The successful inter-laboratory validation led to the publication of the ISO 20130:2018 standard.
• This advancement provides a reliable tool for soil quality evaluation.