SIST EN 15451:2009

EN 15451:2008 - Overview

EN 15451:2008 (CEN) specifies a validated chromatographic method for the determination of the total amount of iron chelated by EDDHSA (Fe3+/EDDHSA) in commercial fertilizer products. The standard defines sample preparation, reagents, HPLC (ion‑pair) separation, detection, calibration and reporting requirements to obtain reproducible quantitative results.

Key topics and technical requirements

• Analytical principle: ion‑pair high‑performance liquid chromatography (HPLC) on a reverse‑phase C18 column. An ion‑pair reagent (tetrabutylammonium, TBA+) forms ion pairs with anionic iron chelates; retention is controlled by an aqueous/acetonitrile gradient.
• Detection: UV photometry at 480 nm (or diode array); Fe3+/EDDHSA typically produces two closely eluting peaks (two forms) that are integrated together.
• Chromatographic system: gradient pump, 20 µL injection loop, C18 column (example: 150 × 3.9 mm, 5 µm), flow rate 1.5 mL/min and a linear gradient between eluents A and B (both contain TBA and acetonitrile in different proportions).
• Reagents & standards: analytical‑grade reagents, ultrapure water (EN ISO 3696), Fe(III) nitrate stock and an Fe3+/EDDHSA standard prepared according to the method (pH adjustments, precipitation of excess Fe, filtration). Calibration curve uses standards at 1, 5, 10, 25, 50 and 100 mg Fe/L.
• Sample prep: aqueous extraction (typical example: ~125 mg sample stirred in 80 mL water for 30 min, diluted to 100 mL) and filtration (0.45 µm) prior to injection.
• Interferences & specificity: no interferences detected for common chelates (o,o‑EDDHA, o,p‑EDDHA, EDTA, DTPA, etc.); these compounds are separated from Fe3+/EDDHSA.
• Precision: repeatability and reproducibility were established through inter‑laboratory tests; reproducibility limits can be higher than regulatory tolerances for micronutrient content (see standard Annex C).

Practical applications

• Routine quality control and batch certification of fertilizers and micronutrient formulations containing EDDHSA.
• Verification of label claims for chelated iron content in fertilizers, foliar feeds and soil amendments.
• Use in regulatory testing, manufacturer QC laboratories, contract analytical labs and research labs developing chelated micronutrient products.

Who should use this standard

• Fertilizer manufacturers and formulation chemists
• Agricultural testing laboratories and accreditation bodies
• Regulatory authorities monitoring fertilizer composition
• Contract analytical service providers offering HPLC-based micronutrient assays

Related standards

• EN 1482‑2 - Sampling and sample preparation for fertilizers
• EN ISO 3696 - Water for analytical laboratory use

Keywords: EN 15451:2008, Fe3+/EDDHSA, ion‑pair chromatography, EDDHSA, iron chelate determination, fertilizers, HPLC, tetrabutylammonium, calibration curve, fertilizer quality control.