🌱 Total content of micronutrients in mineral fertilizers — extraction of boron, cobalt, copper, iron, manganese, molybdenum and zinc with aqua regia before determination by FAAS, ICP-OES, spectrophotometry or titration, PN-EN 16964

Physicochemistry PN-EN 16964

Overview

WHAT THE STANDARD COVERS. Scope from the PKN card (Polish version), in full: "This European Standard specifies a method for the total extraction of boron, cobalt, copper, iron, manganese, molybdenum and zinc with aqua regia from mineral fertilizers containing at least one micronutrient. The extracts can be analysed according to EN 16963, EN 16965, prEN 17041, prEN 17042 and prEN 17043. This method is also suitable for the extraction of cadmium, chromium, nickel and lead to be determined according to EN 16319; for the extraction of mercury to be determined according to EN 16320, and for the extraction of arsenic to be determined according to EN 16317." The standard therefore describes only the preparation of the extract — the result is given only by the determination standard. The card does not give the sample mass, the proportions of the acids, the temperature and time of extraction or the filtration. We did not have the text of the standard (12 pages).

STATUS (state of the cards on 30 September 2026). The card of PN-EN 16964:2018-03 (Polish version) has no "Withdrawn" header — the standard is CURRENT: published 13-11-2019, 12 pages, price group F, Chemistry Sector, KT 156 for Fertilizers, ICS 65.080, "Introduces: EN 16964:2018 [IDT]"; the card has no "Replaces" field. English version: published 06-03-2018, 10 pages, price group E; the "Scope" fields of both cards have the same content in slightly different wording (including the sentence on cadmium, chromium, nickel, lead, mercury and arsenic). The PKN search for "PN-EN 16964" (30 September 2026) shows three items: this standard in the Polish and English versions and PN-EN ISO 16964:2020-10 (English version; EN ISO 16964:2020, ISO 16964:2019 IDT) — a different document with the same number and the ISO element, which does not appear under this number in the accreditation scopes.

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 16964: 30 records at 10 laboratories; in the current PCA documents the number appears 29 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 16964:2018-03"; these are the same laboratories as for PN-EN 16965 — eight regional chemical-agricultural stations as well as AB 006 and AB 180. The "Laboratories" tab looks for notations that BEGIN with "PN-EN 16964" and will show all 10 laboratories — checked with the tab's query on the production server labcoda.pl on 30 September 2026: 10. 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 44 pairs of range limits from the copy (including 5 at AB 1186, recorded in the copy in the description of the test) appears in the current document and no entry is suspended.

WHAT IS DETERMINED AFTER THIS EXTRACTION. In every entry this standard stands next to a determination standard. Copper, manganese and zinc by FAAS according to PN-EN 16965 — all 10 laboratories, iron — 9 (without AB 277), cobalt — AB 180 (FAAS) and AB 006 (ICP-OES). Boron spectrophotometrically according to PN-EN 17041:2018-07 — 7 laboratories (AB 006, AB 180, AB 312, AB 317, AB 827, AB 921, AB 1186), range from 0.0010 % to 21.0 % (upper limit at AB 180), and above 10.0 % titrimetrically according to PN-EN 17042:2018-07 — AB 006, (10.0 – 20.0) %. ICP-OES according to PN-EN 16963:2018-03 — AB 006: boron, cobalt, copper, iron, manganese, molybdenum and zinc. Five laboratories (AB 284, AB 312, AB 333, AB 827, AB 921) enter this standard together with PN-EN 16962 (extraction with water) in one entry; AB 006, AB 180, AB 277, AB 317 and AB 1186 have separate entries for the total and the water-soluble content. Materials: mineral (inorganic) fertilizers — all; AB 006 also fertilizer limes, liming materials and organo-mineral fertilizers, and in the FAAS and ICP-OES entries also urea, organic fertilizers, compost, growing media and products supporting plant cultivation.

ALONGSIDE THIS STANDARD. The determinations of contaminants that the card lists as possible after this extraction appear in the scopes without it: cadmium, chromium, nickel and lead according to PN-EN 16319+A1:2016-02 — AB 006, AB 180 (with procedure PB 35) and AB 1095; arsenic according to PN-EN 16317 — AB 006; mercury according to PN-EN 16320 — AB 1095. The water-soluble content of micronutrients is obtained by extraction according to PN-EN 16962 (a separate Knowledge Base entry), and the FAAS measurement by PN-EN 16965 (a separate entry). Aqua regia extraction of trace elements from soil is described in PN-ISO 11466 — also a separate entry, a different matrix.

WHERE A SEEMINGLY CORRECT RESULT IS EASY TO GET. First — "total" means here: extracted with aqua regia, not completely decomposed; it is a conventional content according to this procedure. Second — which extraction: five laboratories record both extraction standards (with water and with aqua regia) in one entry, so the report has to be checked to see whether the result is the total or the water-soluble content. Third — the determination standard: the same extract gives an FAAS result (PN-EN 16965), an ICP-OES result (PN-EN 16963) or a spectrophotometric and titrimetric result for boron (PN-EN 17041, PN-EN 17042) — the report should give both standards. Fourth — the material: the scope on the card concerns mineral fertilizers containing micronutrients, while AB 006 also applies this extraction to organic fertilizers, compost and growing media — this goes beyond the scope described on the card.

WHAT WE DO NOT GIVE. We did not have the text of the standard — PKN sells it (12 pages). We do not give the sample mass, the composition and volume of aqua regia, the temperature and time of extraction, the way of filtering and making up to volume or the blank.

Method principle

According to the PKN card, boron, cobalt, copper, iron, manganese, molybdenum and zinc are extracted from a mineral fertilizer with aqua regia (a mixture of hydrochloric and nitric acids) and determined in the extract according to separate standards — EN 16963 (ICP-OES), EN 16965 (FAAS) or EN 17041 and EN 17042 (boron); the extract is also suitable for determining cadmium, chromium, nickel, lead (EN 16319), mercury (EN 16320) and arsenic (EN 16317). We DO NOT GIVE the extraction conditions — we did not have the text of the standard.

Applications

• Mineral (inorganic) fertilizers containing micronutrients — total content of boron, cobalt, copper, iron, manganese, molybdenum and zinc — in the scopes of 10 laboratories
• Fertilizer limes, liming materials and organo-mineral fertilizers and — with FAAS and ICP-OES — urea, organic fertilizers, compost and growing media (AB 006)

Key parameters

Standard

Standard number

PN-EN 16964:2018-03 (wersja polska i angielska; EN 16964:2018 IDT)

Title (PL)

Nawozy — Ekstrakcja całkowitej zawartości mikroskładników pokarmowych w nawozach wodą królewską

Title (EN)

Fertilizers — Extraction of total micro-nutrients in fertilizers using aqua regia

Step-by-step procedure

1. Status of the document

   PKN card: PN-EN 16964:2018-03 current (state of the card on 30 September 2026).

2. Extraction

   With aqua regia from a mineral fertilizer containing at least one micronutrient; we DO NOT GIVE the sample mass, temperature or time.

3. Determination in the extract

   According to a separate standard: PN-EN 16965 (FAAS), PN-EN 16963 (ICP-OES), PN-EN 17041 or PN-EN 17042 (boron).

4. Result

   Total content (in the sense of this extraction), stating the extraction standard and the determination standard.

Required equipment and apparatus

Reagents, media and consumables

Health and safety (OHS)

• Aqua regia is strongly corrosive and releases chlorine and nitrogen oxides — prepare and heat it only in an efficient fume hood, wearing goggles and acid-resistant gloves
• TECHNICAL NOTE: the "total" content is the result of this particular extraction — without the name of the extraction and of the determination standard the result is not comparable

Frequently asked questions