🌱 Cobalt, copper, iron, manganese and zinc in fertilizers — determination in aqueous extracts (EN 16962) and aqua regia extracts (EN 16964) by flame atomic absorption spectrometry (FAAS), PN-EN 16965

Physicochemistry PN-EN 16965

Overview

WHAT THE STANDARD COVERS. Scope from the PKN card (Polish version), in full: "This European Standard specifies a method for the determination of cobalt, copper, iron, manganese and zinc in fertilizer extracts using flame atomic absorption spectrometry (FAAS). The method is applicable to aqueous and aqua regia fertilizer extracts obtained according to EN 16962 and/or EN 16964. Note: In most cases the presence of small amounts of organic matter does not affect the determination by FAAS and removal of organic matter is not necessary." The standard is therefore only the measurement part. The extraction is described by separate standards: PN-EN 16962 (water-soluble micronutrients and removal of organic compounds from aqueous extracts) and PN-EN 16964 (total content of micronutrients, extraction with aqua regia) — both have separate entries in the Knowledge Base. The card does not give the wavelength, the type of flame, calibration, concentration ranges or precision. We did not have the text of the standard (22 pages).

STATUS (state of the cards on 30 September 2026). The card of PN-EN 16965:2018-03 (Polish version) has no "Withdrawn" header — the standard is CURRENT: published 09-08-2019, 22 pages, price group L, Chemistry Sector, KT 156 for Fertilizers, ICS 65.080, "Introduces: EN 16965:2018 [IDT]"; the card has no "Replaces" field. The English version was published earlier: 06-03-2018, 24 pages, price group M; the "Scope" fields of both cards have the same content in slightly different wording. The PKN search for "PN-EN 16965" (30 September 2026) shows three items: this standard in the Polish and English versions and PN-EN ISO 16965:2026-03 (English version; EN ISO 16965:2025, ISO 16965:2025 IDT) — a different document with the same number and the ISO element: according to its card, the determination of elements in environmental solid matrices by ICP-MS (published 05-03-2026, KT 191 for Soil Chemistry, replaces PN-EN 16171:2017-02).

HOW MANY LABORATORIES AND IN WHAT FORM (copy of the accreditation-scope database, data loaded up to 17 September 2026, read on 30 September 2026). All notations of number 16965 without the ISO element: 34 records at 10 laboratories; in the current PCA documents the number appears 33 times — at AB 827 one cell of reference documents covers two rows (zinc, manganese and iron, and copper), which the copy splits into two records. All laboratories write "PN-EN 16965:2018-03"; eight of them are regional chemical-agricultural stations (AB 277, AB 284, AB 312, AB 317, AB 333, AB 827, AB 921, AB 1186). The "Laboratories" tab looks for notations that BEGIN with "PN-EN 16965" and will show 9 of the 10 laboratories — checked with the tab's query on the production server labcoda.pl on 30 September 2026: 9; it will not show AB 1186, whose notation in the copy joins the standard into one string with the extraction standard ("PN-EN 16964:2018-03 PN-EN 16965:2018-03", "PN-EN 16962:2018-03 PN-EN 16965:2018-03"). PN-EN ISO 16965 (AB 313, ICP-MS, two entries) is counted separately — it is not this standard. Current scopes on the PCA website (read on 30 September 2026, issues from 07.03.2025 to 22.07.2026): all entries are in the issues in force, each of the 50 pairs of range limits from the copy (including 8 at AB 1186, recorded in the copy in the description of the test) appears in the current document and no entry is suspended.

MATERIALS, EXTRACTION AND RANGES. Mineral (inorganic) fertilizers — all 10 laboratories; AB 006 also fertilizer limes, liming materials, urea, organo-mineral and organic fertilizers, compost, growing media and products supporting plant cultivation. Technique — FAAS everywhere. Extraction: separate entries for the total content (with PN-EN 16964) and the water-soluble content (with PN-EN 16962) — AB 006, AB 180, AB 277, AB 317 and AB 1186; both extraction numbers in one entry, without indicating the extract — AB 284, AB 312, AB 333, AB 827 and AB 921; AB 006 also has an entry for chelated micronutrients with PN-EN 13366:2004. Elements: copper, manganese and zinc — all 10 laboratories, iron — 9 (without AB 277), cobalt — only AB 180, (0.0010 – 0.156) %. Ranges: lower limits from 0.001 % to 0.010 % (depending on the laboratory and the element), upper — 10.0 %, and at AB 006 up to 50.0 % copper, 35.0 % manganese and 20.0 % iron and zinc.

ALONGSIDE THIS STANDARD. In the same laboratories: boron — spectrophotometrically according to PN-EN 17041:2018-07 (AB 006, AB 180, AB 284, AB 312, AB 317, AB 827, AB 921, AB 1186; at AB 284 in a separate entry, without an extraction standard) and titrimetrically according to PN-EN 17042:2018-07 (AB 006, (10.0 – 20.0) %); elements by ICP-OES according to PN-EN 16963:2018-03 after the same extractions, also cobalt, boron and molybdenum (AB 006); contaminants — lead, cadmium, chromium and nickel according to PN-EN 16319+A1:2016-02 (AB 006; AB 180 with procedure PB 35); copper in high-nitrogen ammonium nitrate based fertilizers according to CEN/TS 17762:2022, FAAS, (2.00 – 20.0) mg/kg (AB 180). Micronutrients in organic and natural fertilizers are determined by laboratories according to in-house procedures, e.g. AB 277 (PB 07: copper, iron, manganese, zinc; FAAS, in mg/kg), AB 339 (PB 209, FAAS; PB 211, ICP-OES) and AB 696 (PT-LCAW-14: among others boron, cobalt, copper, iron, manganese and molybdenum; ICP-OES and ICP-MS — this procedure also covers inorganic fertilizers, i.e. the subject of this standard).

WHERE A SEEMINGLY CORRECT RESULT IS EASY TO GET. First — which extract: the same figure "copper content" means something different after extraction with water (PN-EN 16962) and with aqua regia (PN-EN 16964); five laboratories put both extraction numbers into one entry, so the report must say which extract was measured. Second — units: in the entries of this standard the ranges are in per cent, while alongside there are copper determinations in mg/kg (CEN/TS 17762, procedures for organic fertilizers) — these are different tests, not a different range of the same method. Third — organic compounds: according to the note in the scope, small amounts usually do not interfere with FAAS, but the removal of organic compounds from aqueous extracts is described in PN-EN 16962 — for fertilizers with organic additives it is worth asking whether it was done. Fourth — cobalt: the method covers it, but in the scopes only AB 180 determines it, with an upper limit of 0.156 %.

WHAT WE DO NOT GIVE. We did not have the text of the standard — PKN sells it (22 pages). We do not give the wavelengths, the type of flame and background correction, the preparation of calibration solutions, dilutions, the way of eliminating interferences, the formula or precision.

Method principle

According to the PKN card, cobalt, copper, iron, manganese and zinc are determined in fertilizer extracts — aqueous according to EN 16962 or aqua regia extracts according to EN 16964 — by flame atomic absorption spectrometry (FAAS). Small amounts of organic matter usually do not interfere and need not be removed. We DO NOT GIVE the measurement conditions — we did not have the text of the standard.

Applications

• Mineral (inorganic) fertilizers containing micronutrients — total content (aqua regia extract) and water-soluble content — in the scopes of 10 laboratories
• Chelated micronutrients (with PN-EN 13366) as well as fertilizer limes, organo-mineral and organic fertilizers, compost and growing media — AB 006

Key parameters

Standard

Standard number

PN-EN 16965:2018-03 (wersja polska i angielska; EN 16965:2018 IDT)

Title (PL)

Nawozy — Oznaczanie kobaltu, miedzi, żelaza, manganu i cynku metodą płomieniowej absorpcyjnej spektrometrii atomowej (FAAS)

Title (EN)

Fertilizers — Determination of cobalt, copper, iron, manganese and zinc using flame atomic absorption spectrometry (FAAS)

Step-by-step procedure

1. Status of the document

   PKN card: PN-EN 16965:2018-03 current (state of the card on 30 September 2026).

2. Extract

   Aqueous according to PN-EN 16962 (water-soluble content) or with aqua regia according to PN-EN 16964 (total content) — the choice of extract must be recorded.

3. Measurement

   FAAS for cobalt, copper, iron, manganese and zinc; we DO NOT GIVE the measurement conditions or calibration.

4. Result

   Content of the element in the fertilizer (in the accreditation scopes — in %), with the name of the extract; we DO NOT GIVE the formula.

Required equipment and apparatus

Health and safety (OHS)

• Aqua regia extracts are strongly acidic and corrosive, and the air–acetylene flame needs an efficient extraction hood above the burner — work according to the spectrometer instructions
• TECHNICAL NOTE: a result without the name of the extraction (PN-EN 16962 or PN-EN 16964) does not say whether it is the total or the water-soluble content

Frequently asked questions