Proficiency test for sample preparation in soil analysis

Grüneberg B.*, Koch M. (*LLBB) 
Proficiency test for sample preparation in soil analysis
Poster im Rahmen des 10th Workshop on Proficiency Testing in Analytical Chemistry, Microbiology and Laboratory Medicine, 25. – 28.09.2023 in Windsor, UK

A proficiency test on sample preparation for soil for analysis of dry residue, loss on ignition, ammonium-N and nitrate-N in CaCl2-Extract, pH, electrical conductivity, total carbon and total nitrogen was organised by Landeslabor Berlin-Brandenburg (LLBB). Samples were based on fresh soil that has been rubbed through a coarse sieve (approx. 5 mm) to remove stones and coarse organic material. 16 aliquots were prepared and packed in plastic bags.
Eight aliquots were used for internal purposes in the PT providers’ laboratory and eight aliquots were sent to external laboratories. Participants were requested to perform the complete sample preparation and to send back prepared samples as well as the results of their own (triplicate) analyses.
Sample preparation included homogenisation of fresh sample, drying of the complete sample, sieving (2 mm) and documentation of sample proportions (< 2 mm  and > 2 mm), sample dividing, grinding to < 250 µm (grinding only for total carbon and total nitrogen).