🌱 Lead content in agricultural limes and liming materials containing magnesium — flame atomic absorption spectrometry (FAAS), PN-C-87006-14

Physicochemistry PN-C-87006-14

Overview

WHAT THE STANDARD COVERS. The “Scope” field of the PKN card of PN-C-87006-14:1993 (Polish version), in full (spelling of the card): “An atomic absorption spectrophotometry method using a graphite furnace and in an acetylene-air flame and a voltammeter method are given for determining the lead content in calcium-magnesium fertilizers. These methods are used for all calcium-magnesium fertilizers. The purity of reagents, the weighing accuracy and the interpretation of results are specified”. The card does not say which clauses of the standard correspond to the individual methods, how the sample solution is prepared or in what concentration range each of them is applied.

STATUS (PKN card as of 06.11.2026). The card of PN-C-87006-14:1993 (Polish version): label “Withdrawn”, title “Nawozy sztuczne wapniowo-magnezowe -- Oznaczanie zawartości ołowiu” (Calcium-magnesium fertilizers — Determination of lead content), publication 14-06-1993, “Withdrawal date: 07-09-2015”, 4 pages, price group B, Chemistry Sector, KT 156 Fertilizers, ICS 65.080. The card has no “Replaces” or “Replaced by” fields — it does NOT indicate a successor.

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 87006-14 appears in the reference document in any notation). 9 records at 9 Polish laboratories, none at Czech laboratories. Notations: “PN-C-87006-14:1993” — AB 312, AB 333, AB 930, AB 1186; “PN-C-87006-14:1993 pkt.4.2” — AB 798; “PN-93/C-87006/14 p.4.2” — AB 317; “PN-93/C-87006/14” — AB 779; “PN-C-87006-14:1993, p. 4.2” together with “PN-C-87007-09:1993, p. 4.2” — AB 339; together with PN-C-87007-09:1993 and PN-C-87070-05:1992 — AB 277. Clause 4.2 is 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-87006-14”) shows the same 9 laboratories — including those that write the number as “PN-93/C-87006/14” (query of the tab on labcoda.pl, 06.11.2026).

WHAT THE LABORATORIES TEST (complete entries). All 9 — “Lead content”, technique: flame atomic absorption spectrometry (FAAS). Objects and ranges: agricultural limes containing magnesium — AB 312 (5,0 – 700) mg/kg, AB 1186 (5,00 - 700) mg/kg; agricultural lime containing magnesium — AB 798 (20,0 - 330) mg/kg; agricultural lime containing magnesium (calcium-magnesium fertilizer) — AB 333 (5,0 - 5000) mg/kg; agricultural limes and liming materials containing magnesium — AB 317 (10,0 - 200) mg/kg, AB 779 (10,0 - 100,0) mg/kg; calcium-magnesium fertilizers, liming materials — AB 930 (20,0 – 200) mg/kg; agricultural limes, liming materials — AB 339 (5,0 – 1000) mg/kg, in one entry with PN-C-87007-09:1993; mineral (inorganic) fertilizers — AB 277 (5,0 - 500) mg/kg, in one entry with PN-C-87007-09:1993 and PN-C-87070-05:1992. 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. At AB 339 one entry (“agricultural limes, liming materials”) cites this standard together with PN-C-87007-09:1993, and at AB 277 (“mineral (inorganic) fertilizers”) — together with PN-C-87007-09:1993 and PN-C-87070-05:1992; the entries do not say which standard applies to which fertilizer.

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. Lead in limes without magnesium is determined by the same laboratories, except AB 798, according to PN-C-87007-09:1993 (a separate Knowledge Base entry); AB 798 does not have lead in limes without magnesium in its scope. By ICP-OES, lead (together with cadmium, 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 (2,00 - 300) mg/kg — without this standard. Cadmium in the same limes containing magnesium is determined by the same 9 laboratories according to PN-C-87006-15:1996 (a separate Knowledge Base entry).

STATUS OF THE STANDARDS NAMED ALONGSIDE (PKN cards, read on 06.11.2026). PN-C-87007-09:1993 — withdrawn 07-09-2015; PN-C-87070-05:1992 (lead in nitrogen and phosphorus fertilizers) — withdrawn 30-05-2014; 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-87006-15:1996 — withdrawn 05-08-2022; PN-C-87006-11:1990 (calcium and magnesium in calcium-magnesium fertilizers) — withdrawn 07-11-2011.

WHERE A SEEMINGLY CORRECT RESULT IS EASY TO GET. First — the reference basis in the assessment: the value of 600 mg in the regulation refers to a kilogram of the sum of CaO + MgO, whereas the laboratories report lead in mg/kg. A result in mg/kg of fertilizer compared directly with the number 600 looks compliant, although after conversion it may exceed it — our arithmetic example: 400 mg/kg of lead in a lime containing a total of 50 % CaO + MgO is 800 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: for lime without magnesium the laboratories use a different standard (PN-C-87007-09), and the regulation a different criterion — 200 mg of lead per kilogram of CaO, three times less and on a different basis; confusing the type changes both the method and the criterion. Third — the upper limit of the range: at AB 317 and AB 930 the range ends at 200 mg/kg, at AB 779 — at 100,0 mg/kg, at AB 798 — at 330 mg/kg; a result above the upper limit is not covered by accreditation. For a lime containing 50 % CaO + MgO the permissible value corresponds to 300 mg/kg of fertilizer (our calculation) — more than the upper limit of the range at AB 317, AB 779 and AB 930. Fourth — the method: the card lists atomic absorption spectrometry with a graphite furnace and in an acetylene–air flame as well as voltammetry, while the laboratories list one technique (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 — when ordering, it is worth making sure which method was used for the determination.

WHAT WE DO NOT GIVE. We did not have the text of the standard — PKN makes it available for a fee (4 pages). We do not give the method of sample digestion, the wavelength, the calibration procedure, the formulas, the permissible difference between results or the content of clause 4.2, which three laboratories indicate. 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, lead in a calcium-magnesium fertilizer is determined by atomic absorption spectrometry — with a graphite furnace or in an acetylene–air flame — or by a voltammetric method. 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

• Lead in agricultural limes and liming materials containing magnesium (calcium-magnesium fertilizers) — 9 Polish laboratories, all by FAAS
• Checking the permissible lead content in agricultural lime containing magnesium: 600 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-C-87007-09:1993, not according to this standard

Key parameters

Standard

Standard number

PN-C-87006-14:1993

Title (PL)

Nawozy sztuczne wapniowo-magnezowe — Oznaczanie zawartości ołowiu

Title (EN)

Calcium-magnesium fertilizers — Determination of lead content

Step-by-step procedure

1. Status of the document

   PKN card: standard withdrawn 07-09-2015, 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-C-87007-09:1993.

3. Determination of lead

   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

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

5. Comparison with legislation

   The permissible value of 600 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)

• Lead and its compounds are toxic — standard solutions and waste are stored and disposed of as hazardous substances
• Flame in the AAS spectrometer: gas installation and fume hood above the 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