🌱 Calcium oxide and magnesium oxide in agricultural limes and liming materials containing magnesium — complexometric titration (disodium EDTA, EGTA, DCTA), PN-C-87006-11

Physicochemistry PN-C-87006-11

Overview

WHAT THE STANDARD COVERS. The scope from the PKN card, quoted in full (spelling as on the card): "A complexometric method with disodium edetate, with complexone Vi (egta) and with complexone iV (dtca) is given for the determination of the calcium and magnesium content of calcium-magnesium fertilizers. These methods are used for all types of calcium-magnesium fertilizers. The purity of reagents, accuracy of weighing, final result of the determination and preparation of samples for testing are specified" (our translation of the Polish card). The card thus names three complexing reagents — disodium edetate, complexone VI (EGTA) and complexone IV (DCTA) — but does not say which is used for calcium and which for magnesium, nor at what pH and with which indicators the titration is carried out.

STATUS (state of the card on 29 September 2026). Card of PN-C-87006-11:1990 (Polish version): header "Wycofana" (withdrawn), published 29-10-1990, "Withdrawal date: 07-11-2011", 5 pages, price group C, Chemical Sector, PKN technical committee KT 156 (Fertilizers), ICS 65.080; there are no "Supersedes" and "Replaced by" fields. The PKN search for "PN-C-87006-11" (29 September 2026) shows only this one edition; we did NOT ESTABLISH a successor.

HOW MANY LABORATORIES AND IN WHAT FORM (copy of the accreditation scope database, data up to 17 September 2026, read on 28 September 2026). All records of number 87006-11: 18 entries at 12 laboratories. Forms: "PN-C-87006-11:1990" — 6 laboratories (AB 277, AB 312, AB 333, AB 798, AB 820, AB 1186), "PN-90/C-87006/11" — 4 (AB 317, AB 759, AB 921, AB 930), "PN-C-87006/11:1990" — AB 779, "PN-90/C-87006-11" — AB 789. Clauses: calcium oxide "clause 4", magnesium oxide "clause 6" (AB 317, AB 930; AB 798 — "clause 4 excluding clause 4.5" and "clause 6 excluding clause 6.5"), "excluding clauses 4.5, 6.5" (AB 333), "excluding clause 4.5" (AB 820, for both quantities), "excluding clauses 5 and 7" (AB 759), "clauses 1, 2, 3, 4, 6" (AB 921). The "Laboratories" tab searches for records BEGINNING with "PN-C-87006-11" and will show 6 laboratories — checked with the tab query on the labcoda.pl production server on 29 September 2026: 6; under "PN-90/C-87006/11" — 4, under "PN-C-87006/11" — 1, under "PN-90/C-87006-11" — 1. Current scopes on the PCA website (read on 29 September 2026, issues from 24 June 2025 to 5 August 2026): all entries stand in the valid issues, every pair of range limits from the copy appears in the current document and no entry is suspended.

TEST ITEM, TECHNIQUE AND RANGES. Agricultural limes containing magnesium — AB 312, AB 333, AB 759, AB 798, AB 820, AB 921, AB 1186; agricultural limes and liming materials containing magnesium — AB 317, AB 779, AB 789; calcium-magnesium fertilizers and liming materials — AB 930; agricultural limes and liming materials — AB 277 (calcium oxide in the same entry as PN-C-87007-06:1993+Az1:1997). Technique: titrimetric method for all. Determined: calcium oxide and magnesium oxide — 11 laboratories; AB 1186 — calcium oxide only (it determines magnesium under PN-EN 12947:2003 by flame AAS). Ranges in percent: CaO from (0.50 – 80.0) (AB 312) and (0.50 − 60.0) (AB 921) to (15.0 - 50.0) (AB 798) and (20.0 – 90.0) (AB 930); MgO from (0.50 – 25.0) (AB 312, AB 317, AB 921) to (5.00 – 30.0) (AB 759) and (1.5 - 60.0) (AB 820).

ALONGSIDE THIS STANDARD. Calcium oxide in limes without magnesium is determined by the same laboratories under PN-C-87007-06:1993 (a separate Knowledge Base entry) — 11 of 12, all except AB 798. Under European standards calcium and magnesium in liming materials are determined by AB 006, AB 180 and AB 339 (PN-EN 13475:2003 — calcium, PN-EN 12947:2003 — magnesium), and AB 006 also under PN-EN 12946:2023-11; PN-EN 12947:2003 is also cited by AB 1186.

WHAT WE DO NOT GIVE. We did not have the text of the standard — PKN sells it (5 pages). We do not give the sample mass, how it is dissolved, the pH and indicators of the titration, the titrant concentrations, the formulae, the permissible differences or the content of clauses 4.5, 5, 6.5 and 7 that laboratories exclude; nor do we know which of the three complexones corresponds to which clause.

Method principle

According to the PKN card, calcium and magnesium in the solution of a calcium-magnesium fertilizer sample are determined by complexometric titration — with disodium edetate, complexone VI (EGTA) or complexone IV (DCTA); laboratories report the results as calcium oxide and magnesium oxide. We do NOT GIVE the titration conditions — we did not have the text of the standard.

Applications

• Calcium oxide and magnesium oxide in agricultural limes and liming materials containing magnesium — in the scopes of 12 laboratories
• Calcium-magnesium fertilizers (AB 930); limes without magnesium — under PN-C-87007-06, not under this standard

Key parameters

Standard

Standard number

PN-C-87006-11:1990 (wersja polska)

Title (PL)

Nawozy sztuczne wapniowo-magnezowe — Oznaczanie wapnia i magnezu

Title (EN)

Calcium-magnesium fertilizers — Determination of calcium and magnesium

Step-by-step procedure

1. Status of the document

   PKN card: the standard withdrawn 07-11-2011, without a successor being named (state of the card on 29 September 2026).

2. Sample solution

   Preparation of a solution from the agricultural lime sample; mass and method of dissolution NOT GIVEN.

3. Determination of calcium and magnesium

   Complexometric titration — according to the card with disodium edetate, complexone VI (EGTA) or complexone IV (DCTA); in the scopes calcium oxide is named as "clause 4", magnesium oxide as "clause 6"; pH, indicators and concentrations NOT GIVEN.

4. Result

   Calcium oxide and magnesium oxide content in percent; formulae and permissible differences NOT GIVEN.

Health and safety (OHS)

• Quicklime reacts with water, releasing heat, and is corrosive — eye and skin protection when preparing the sample
• SUBSTANTIVE NOTE: for limes without magnesium the scopes cite another standard (PN-C-87007-06:1993) — when asking for the test, state the type of lime

Frequently asked questions