Overview
CEN/TR 15106:2005 (CEN Technical Report) compares analytical methods for the determination of the chelating agents EDDHA and EDDHMA in fertilizers. The report evaluates the standardized ion chromatography method (EN 13368-2:2001) against a non‑standardized ion‑pair chromatography approach (the "Lucena method", given in Annex A) using two inter‑laboratory ring tests (A and B). It includes statistical assessments (univariate multifactorial ANOVA, F‑test) to verify repeatability and reproducibility.
Key topics and technical requirements
- Purpose: comparative performance assessment of two HPLC‑based methods for quantifying Fe‑EDDHA and Fe‑EDDHMA.
- Methods evaluated:
- EN 13368-2:2001 - ion chromatography standardized procedure.
- Lucena method - ion‑pair chromatography (informative Annex A), with modifications proposed after ring test A and used in ring test B.
- Test design:
- Two ring tests (A and B) involving multiple laboratories and both solid commercial chelates and solution standards.
- Laboratories requested to perform duplicate analyses and report results to two decimal places where applicable.
- Statistical analysis:
- Calculations per ISO 5725‑2 for repeatability (r), reproducibility (R), and relative standard deviations (RSD).
- Use of ANOVA and F‑tests to assess significance of differences between methods and to identify outliers.
- Annexes:
- Annex A: full non‑standardized (Lucena) method and modifications.
- Annex B/C: laboratory comments and suggested improvements.
Practical applications and users
- Who uses this standard:
- Analytical and QC laboratories performing determination of EDDHA and EDDHMA in fertilizer products.
- Fertilizer manufacturers and formulators for quality assurance of iron chelate products.
- Regulatory bodies and conformity assessment bodies enforcing EU fertilizer labeling and composition (e.g., Regulation (EC) No 2003/2003).
- Method developers and standardization working groups evaluating alternative analytical techniques.
- Practical value:
- Supports method selection between ion chromatography and ion‑pair chromatography for chelate analysis.
- Provides inter‑laboratory performance data (repeatability/reproducibility) to inform method validation and potential standardization of the Lucena method.
- Supplies procedural guidance and suggested modifications (e.g., standard preparation, filtration, calibration and integration practices) to improve analytical robustness.
Related standards
- EN 13368-2:2001 - Fertilizers - Determination of chelating agents by ion chromatography - Part 2: EDDHA and EDDHMA (referenced and compared throughout CEN/TR 15106:2005).
- ISO 5725‑2 - Methods for determining repeatability and reproducibility of measurement methods (used for statistical evaluation).
Keywords: fertilizers, EDDHA, EDDHMA, chelating agents, ion pair chromatography, ion chromatography, Lucena method, EN 13368-2, ring test, repeatability, reproducibility, ANOVA, F-test, fertilizer quality control.