🌱 Cadmium content in agricultural limes and liming materials containing magnesium — flame atomic absorption spectrometry (FAAS), PN-C-87006-15

Physicochemistry PN-C-87006-15

Overview

WHAT THE STANDARD COVERS. The “Scope” field of the PKN card of PN-C-87006-15:1996 (Polish version), in full: “Three methods are specified for determining the cadmium content in calcium-magnesium fertilizers of all types and varieties, including two methods of atomic absorption spectrophotometry (using a graphite furnace and in an acetylene-air flame) and a voltammetric method. For each method, the principle, the reagents and solutions used and the apparatus are given, the preparation of the standard scale, the preparation of the calibration curve, the performance of determinations and the calculation of results are described, and the permissible difference between determination results is given”. The card does not say which clauses of the standard correspond to the three methods, how the sample solution is prepared or in what concentration range each method is applied.

STATUS (PKN card as of 06.11.2026). The card of PN-C-87006-15:1996 (Polish version): label “Withdrawn”, title “Nawozy sztuczne wapniowo-magnezowe -- Oznaczanie kadmu” (Calcium-magnesium fertilizers — Determination of cadmium), publication 16-02-1996, “Withdrawal date: 05-08-2022”, 5 pages, price group C, Chemistry Sector, KT 156 Fertilizers, ICS 65.080. The card has no “Replaces” or “Replaced by” fields — it does NOT indicate a successor. The sister sheet on cadmium in calcium fertilizers is different: the card of PN-C-87007-10:1993 has the label “Withdrawn and replaced by”, the withdrawal date 15-03-2006 and the field “Replaced by: PN-EN 14888:2006 - English version”. For calcium-magnesium fertilizers the card gives no such indication; whether PN-EN 14888 also covers them does not follow from the cards — AB 277 and AB 339 cite both standards in one entry.

HOW MANY LABORATORIES AND IN WHAT FORM (copy of the accreditation scope database refreshed from the production server on 02.11.2026, read on 06.11.2026; counted are records in which number 87006-15 appears in the reference document in any notation). 9 records at 9 Polish laboratories, none at Czech laboratories. Notations: “PN-C-87006-15:1996” — AB 312, AB 333, AB 779, AB 930, AB 1186; “PN-C-87006-15:1996 p.4.2” — AB 317; “PN-C-87006-15:1996 pkt.4.2” — AB 798; “PN-C-87006-15:1996, p. 4.2” together with “PN-EN 14888:2006, metoda A” — AB 339; together with PN-EN 14888:2006 and PN-C-87070-04:1992+Az1:1997 — AB 277. Clause 4.2 is thus indicated by 3 laboratories out of 9. In the current scope documents on the PCA website (read on 06.11.2026, issues from 24.06.2025 to 05.08.2026) the standard appears at the same 9 laboratories, once each, with the same notations and ranges as in the copy; none of these entries is suspended. The “Laboratories” tab (“PN-C-87006-15”) shows the same 9 laboratories (query of the tab on labcoda.pl, 06.11.2026).

WHAT THE LABORATORIES TEST (complete entries). All 9 — “Cadmium content”, technique: flame atomic absorption spectrometry (FAAS). Objects and ranges: agricultural limes containing magnesium — AB 312 (1,0 – 15,0) mg/kg, AB 1186 (0,50 – 75,0) mg/kg; agricultural lime containing magnesium — AB 798 (1,0 - 33,0) mg/kg; agricultural lime containing magnesium (calcium-magnesium fertilizer) — AB 333 (0,50 - 100) mg/kg; agricultural limes and liming materials containing magnesium — AB 317 (1,00 - 20,0) mg/kg, AB 779 (1,00 - 25,0) mg/kg; calcium-magnesium fertilizers, liming materials — AB 930 (1,0 – 20,0) mg/kg; agricultural limes, liming materials — AB 339 (1,0 – 50,0) mg/kg, in one entry with PN-EN 14888:2006 method A; mineral (inorganic) fertilizers — AB 277 (0,25 - 15,0) mg/kg, in one entry with PN-EN 14888:2006 and PN-C-87070-04:1992+Az1:1997. The ranges are given in mg/kg; the scope documents do not say whether this means a kilogram of fertilizer as delivered or of dry matter.

PERMISSIBLE CONTENT IN LEGISLATION. Regulation of the Minister of Agriculture and Rural Development of 9 August 2024 on the implementation of certain provisions of the Act on fertilizers and fertilization (Journal of Laws 2024 item 1261, in force since 05.09.2024 according to the ELI service of the Sejm, read on 06.11.2026), § 13(3): the permissible content of contaminants in agricultural lime containing magnesium does not exceed 15 mg of cadmium (Cd) and 600 mg of lead (Pb) “per kilogram of the sum of calcium oxide and magnesium oxide (CaO + MgO)”; in agricultural lime without magnesium — 8 mg of cadmium and 200 mg of lead per kilogram of calcium oxide (CaO). The same values and the same reference bases were contained in § 14(4) of the previous regulation of 18 June 2008 (Journal of Laws 2008 No. 119 item 765), deemed repealed as of 05.09.2024; the only regulation amending it (of 21 December 2009, Journal of Laws 2009 No. 224 item 1804) did not change § 14. The entire text of the 2024 regulation contains no reference to any standard or test method.

NEXT TO THIS STANDARD. Cadmium in limes without magnesium is determined by the same laboratories according to PN-EN 14888:2006 (AB 312, AB 333, AB 930, AB 1186, and AB 277 and AB 339 — in the same entries as this standard); AB 779 — according to its own procedure PB 60, edition 3 of 01.03.2023. AB 317 and AB 798 do not have cadmium in limes without magnesium in their scopes. By ICP-OES, cadmium (together with lead, chromium and nickel) in agricultural limes and liming materials is determined according to PN-EN 16319+A1:2016-02 by AB 006 (1,00 - 500) mg/kg and AB 180 (0.50 - 50.0) mg/kg — without this standard. Lead in the same limes containing magnesium is determined by the same 9 laboratories according to PN-C-87006-14:1993 (a separate Knowledge Base entry).

STATUS OF THE STANDARDS NAMED ALONGSIDE (PKN cards, read on 06.11.2026). PN-EN 14888:2006 (Polish version, “Fertilizers and liming materials — Determination of cadmium content”, adopts EN 14888:2005) — no withdrawal label; PN-EN 16319+A1:2016-02 (English version, determination of cadmium, chromium, lead and nickel by ICP-AES after aqua regia dissolution; adopts EN 16319:2013+A1:2015) — no withdrawal label; PN-C-87070-04:1992 (cadmium in nitrogen and phosphorus fertilizers) — withdrawn 30-05-2014; we did not check amendment Az1:1997 separately; PN-C-87006-11:1990 (calcium and magnesium in calcium-magnesium fertilizers) — withdrawn 07-11-2011; PN-C-87006-14:1993 — withdrawn 07-09-2015.

WHERE A SEEMINGLY CORRECT RESULT IS EASY TO GET. First — the reference basis in the assessment: the value of 15 mg in the regulation refers to a kilogram of the sum of CaO + MgO, whereas the laboratories report cadmium in mg/kg. A result in mg/kg of fertilizer compared directly with the number 15 looks compliant, although after conversion it may exceed it — our arithmetic example: 10 mg/kg of cadmium in a lime containing a total of 50 % CaO + MgO is 20 mg per kilogram of CaO + MgO. The conversion requires the calcium oxide and magnesium oxide content of the same sample — in the scopes of 8 of these 9 laboratories determined according to PN-C-87006-11:1990 (at AB 1186 calcium oxide only; AB 339 determines calcium and magnesium according to other standards); these are separate determinations, not part of this standard. Second — the type of lime: lime with magnesium has a different standard (this one) and a different permissible value (15 mg per kg of CaO + MgO) than lime without magnesium (PN-EN 14888 in the scopes; 8 mg per kg of CaO); confusing the type changes both the method and the criterion. Third — the method: the card lists three methods, while the laboratories list one (FAAS); 3 out of 9 indicate “p. 4.2”, the others do not indicate a clause. Whether clause 4.2 is the flame method does not follow from the card (in the card description the flame method is the second of three) — when ordering, it is worth making sure which method was used for the determination. Fourth — the lower limit: the ranges start from 0,25 mg/kg (AB 277) to 1,0 mg/kg; we do not know from what lowest content the standard allows the flame method to be used.

WHAT WE DO NOT GIVE. We did not have the text of the standard — PKN makes it available for a fee (5 pages). We do not give the method of sample digestion, the wavelength, the calibration procedure, the formulas, the permissible difference between results or the clause numbering of the individual methods. We did not check the requirements for liming materials in European Union legislation (CE-marked fertilizing products) — we describe only the national regulation.

Method principle

According to the PKN card, cadmium in a calcium-magnesium fertilizer is determined by one of three methods: atomic absorption spectrometry with a graphite furnace, atomic absorption spectrometry in an acetylene–air flame or voltammetry, from a calibration curve prepared from a standard scale. Accredited laboratories use the flame method (FAAS) and report the result in mg/kg. We DO NOT GIVE the determination conditions — we did not have the text of the standard.

Applications

• Cadmium in agricultural limes and liming materials containing magnesium (calcium-magnesium fertilizers) — 9 Polish laboratories, all by FAAS
• Checking the permissible cadmium content in agricultural lime containing magnesium: 15 mg per kilogram of the sum of CaO + MgO (Journal of Laws 2024 item 1261, § 13(3))
• Limes without magnesium — in the scopes of these laboratories according to PN-EN 14888:2006, not according to this standard

Key parameters

Standard

Standard number

PN-C-87006-15:1996

Title (PL)

Nawozy sztuczne wapniowo-magnezowe — Oznaczanie kadmu

Title (EN)

Calcium-magnesium fertilizers — Determination of cadmium

Step-by-step procedure

1. Status of the document

   PKN card: standard withdrawn 05-08-2022, without a successor being indicated (card as of 06.11.2026).

2. Type of lime

   Establishing whether the lime contains magnesium: for lime with magnesium the laboratories use this standard, for lime without magnesium — PN-EN 14888:2006.

3. Determination of cadmium

   In accreditation scopes: flame atomic absorption spectrometry (FAAS), at 3 laboratories with the note “p. 4.2”; we DO NOT GIVE the sample digestion, calibration and measurement conditions.

4. Result

   Cadmium content in mg/kg; we DO NOT GIVE the formulas and the permissible difference between results.

5. Comparison with legislation

   The permissible value of 15 mg refers to a kilogram of the sum of CaO + MgO (Journal of Laws 2024 item 1261, § 13(3)) — the comparison requires the calcium oxide and magnesium oxide content of the same sample, determined separately.

Required equipment and apparatus

Health and safety (OHS)

• Cadmium and its compounds are toxic — standard solutions and waste are stored and disposed of as hazardous substances
• Acetylene–air flame: gas installation and fume hood above the spectrometer burner
• SUBSTANTIVE NOTE: a result in mg/kg of fertilizer is not the same quantity as the permissible value in mg per kg of CaO + MgO

Frequently asked questions