ISO 14820-2 Fertilizers and liming materials — Sampling and sample preparation — Part 2: Sample preparation

ISO 14820-2:2016 covers the second half of the sampling chain: turning a bulk sample taken in the field into the laboratory sample that will actually be analysed. It was published on 11 April 2016 alongside Part 1.

Preparation involves reduction of the bulk sample to a manageable mass, division to obtain representative sub-samples, comminution where the analytical method requires a finer particle size, and drying or conditioning where the parameter to be determined is expressed on a dry basis. It also addresses packaging and storage of the prepared sample before analysis.

The technical risk this part addresses is segregation. Fertilizer blends and compound granules are rarely homogeneous; every operation that divides a sample — riffling, quartering, coning — can bias the result if performed without care. Preparation procedures exist to make sure the sub-sample analysed carries the same composition as the lot it came from.

For laboratories accredited to ISO/IEC 17025, Part 1 and Part 2 together define the front end of the measurement chain that must be documented and controlled. An out-of-specification result that cannot be traced back to a defensible sampling and preparation procedure is difficult to defend in a commercial dispute or a regulatory challenge.