🌿 Total organic carbon (TOC) in soil, waste, biowaste and sewage sludge — dry combustion, difference method A and direct method B, PN-EN 15936

Environment PN-EN 15936

Overview

WHAT THE STANDARD COVERS. The scope from the PKN catalogue card of the 2022-07 edition, quoted in full: "This document specifies two methods for the determination of total organic carbon (TOC) in samples of sewage sludge, treated biowaste, soil and waste containing more than (0.1 %) carbon in relation to dry matter (dm). NOTE This method can also be applied to other solid environmental matrices, provided that the user verifies its applicability." The card of the 2013-02 edition had one more sentence in the scope: "For sewage sludge, treated biowaste and soil only Method A has been validated." The card does not name the methods; that method A is the difference method (TOC as the difference between total and inorganic carbon — hence its users list TOC "by calculation") and B the direct method follows from the records in accreditation scopes (AB 199: "method B (direct)"). That in the direct method inorganic carbon has to be removed before the measurement follows from the principle itself — at high temperature carbonates also release carbon dioxide; how the standard does it, we do not know.

STATUS (state of the cards on 29 September 2026). The card of PN-EN 15936:2022-07 (English version) carries no withdrawal note — the standard is CURRENT. Published 20-07-2022, 25 pages, PKN technical committee KT 191 (Soil Chemistry), ICS 13.030.01 and 13.080.10; "Introduces: EN 15936:2022 [IDT]"; "Supersedes: PN-EN 15936:2013-02 - English version, PN-EN 15936:2013-02 - Polish version". The card of PN-EN 15936:2013-02 (Polish version): heading "Withdrawn", published 20-12-2019, "Date of withdrawal: 20-07-2022", 28 pages, it introduced EN 15936:2012, "Superseded by: PN-EN 15936:2022-07 - English version". The PKN search shows no Polish version of the 2022 edition (29 September 2026) — the valid text is in English. In this knowledge base PN-ISO 10694 has a separate entry — determination of organic and total carbon in soil after dry combustion, a standard with the same technique for soil.

REGULATION — ACCEPTANCE OF WASTE AT LANDFILLS. The Regulation of the Minister of Economy of 16 July 2015 on the acceptance of waste for landfilling (Journal of Laws 2015 item 1277) lists total organic carbon (TOC) among the criteria: inert waste at a landfill for inert waste — 30 000 mg/kg of dry matter (Annex 2); waste with codes 19 08 05, 19 08 12, 19 08 14, 19 12 12 and from group 20 at a landfill for non-hazardous waste — 5 % of dry matter (Annex 4); hazardous waste at a landfill for hazardous waste — 6 % of dry matter (Annex 5); stable, non-reactive hazardous waste at a landfill for non-hazardous waste — 5 % of dry matter (Annex 6). The regulation does not specify a method for determining TOC.

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 15936: 45 entries at 13 laboratories. Forms: "PN-EN 15936:2022-07" with or without a method note — nine laboratories; "PN-EN 15936" without a year — AB 550 (14 entries) and AB 054 (two of four entries); "PN-EN 15936:2013-02, Metoda A" (method A) — AB 1267 (withdrawn edition; four entries in the copy without the note "Metoda A", six records in three blocks in the current PCA scope); "PN EN 15936:2022-07" without a hyphen — AB 213; "PN-EN ISO 15936:2022-07 metoda B (bezpośrednia)" — AB 199, with an "ISO" that this edition does not have. The "Laboratories" tab searches for records BEGINNING with "PN-EN 15936" and will show 11 laboratories — checked with the tab query on the labcoda.pl production server on 29 September 2026: 11; AB 199 and AB 213 remain outside it. Current scopes on the PCA website (read on 29 September 2026): all entries stand in the valid issues, every numerical range from the copy appears in the current document and no entry is suspended.

METHOD A OR B. Method A (difference) is recorded by five laboratories. AB 687, AB 1095 and AB 1267 give it for all their entries, and each of them has three: total carbon (TC), inorganic carbon (TIC) and TOC "by calculation" (at AB 1267 in three waste blocks; in our copy only TIC and TOC of these entries remained). AB 1140 records method A for its only entry — TC alone. AB 005 — for one of its three entries (soil, TIC alone); for waste it has TIC and TOC "by calculation", but without a letter. Method B (direct) is recorded by AB 199, AB 935 and AB 213 for one of its three entries; AB 680 writes "excluding Method A". Four laboratories give no letter at all: AB 054, AB 313, AB 418 and AB 550 (AB 550 has TC, TIC and TOC "by calculation" for four groups of matrices). Technique: high-temperature combustion with infrared detection — ten laboratories (AB 054, AB 213, AB 313, AB 418, AB 550, AB 687, AB 935, AB 1095, AB 1140 and AB 1267 for total carbon); infrared spectrometry — AB 005, AB 199 and AB 680; AB 1267 for inorganic carbon — decarbonisation with phosphoric acid and IR detection; AB 687 for inorganic carbon (TIC) — a gravimetric method.

MATRICES OUTSIDE THE TITLE OF THE STANDARD. The title of the standard names soil, waste, treated biowaste and sewage sludge. In the scopes it is also cited for: solid fuels and solid biomass and plastics (AB 054), solid fuels, biomass ash, construction raw materials and materials and "waste gas samples" collected on filters (AB 550), construction materials, compost and plant cultivation aids (AB 213), ceramic raw materials and materials (AB 687), organic, natural and mineral fertilisers (AB 1095), zinc-bearing materials (AB 1140). In its note the card allows "other solid environmental matrices, provided that the user verifies its applicability"; whether fuels, plastics or construction materials belong to them the card does not decide. For a result for such a matrix it is worth asking the laboratory about this verification.

RANGES. In percent: lower limits from 0.03 % (inorganic carbon at AB 005) and 0.10 % (among others AB 199, AB 213, AB 687, AB 1140) to 3.2 % (AB 680, waste), upper limits from 7.9 % (AB 680, soil) to 90 % (AB 054, plastics). In mass units: AB 418 — 5000–800 000 mg/kg, AB 935 — 2000–60 000 mg/kg, AB 313 — 1–500 g/kg, AB 199 — 1.0–400 g/kg; AB 550 for filters from waste gases — 0.1–2 mg of carbon in the sample.

ALONGSIDE THIS STANDARD. For total organic carbon in soil, waste, sludge, composts and fertilisers the scopes cite alongside this standard (full list of standards; apart from them in-house procedures and the general records "Normy" (standards) and "Procedury" (procedures)): PN-ISO 10694:2002 — 12 laboratories (AB 005, AB 054, AB 201, AB 300, AB 313, AB 322, AB 418, AB 447, AB 550, AB 646, AB 1095, AB 1270; AB 313 and AB 322 write "PN-EN 10694:2002", and AB 313 and AB 550 cite it in the same entry as PN-EN 15936); PN-EN 13137:2004 — six (AB 054, AB 300, AB 418, AB 550, AB 646, AB 769; at AB 418 in the PCA scope for construction materials — in our copy this row erroneously carries the number PN-EN 14039:2008 from the neighbouring row on mineral oil); PN-ISO 14235:2003 — AB 869 and AB 1748. For organic carbon in aqueous eluates from waste — PN-EN 1484:1999 together with standards of the PN-EN 12457 series, at AB 300 also with PN-EN ISO 20236:2025-05.

WHAT WE DO NOT GIVE. We did not have the text of the standard — PKN sells it. We do not give the sample preparation, the combustion temperature, the way inorganic carbon is removed in method B, the calibration, the criteria for choosing the method or the precision.

Method principle

According to the title and the card of the standard, organic carbon in soil, waste, treated biowaste and sewage sludge is determined by dry combustion: in method A (difference) from the difference between total and inorganic carbon, in method B (direct) after removal of inorganic carbon from the sample. The result in percent of dry matter is compared, among other things, with the criteria for accepting waste at landfills (3 %, 5 % or 6 % of dry matter — Journal of Laws 2015 item 1277). We DO NOT GIVE the temperature, sample preparation or calibration — we did not have the text of the standard.

Applications

• Acceptance of waste at landfills — TOC among the criteria of the regulation (Journal of Laws 2015 item 1277, Annexes 2, 4, 5 and 6)
• Soil, waste, treated biowaste, sewage sludge — in the accreditation scopes of 13 laboratories; some extend the standard to fuels, plastics, construction materials, fertilisers and filters from waste gases

Key parameters

Standard

Standard number

PN-EN 15936:2022-07 (wersja angielska)

Title (PL)

Gleba, odpady, uzdatnione bioodpady oraz osady ściekowe — Oznaczanie całkowitej zawartości węgla organicznego (TOC) po suchym spalaniu

Title (EN)

Soil, waste, treated biowaste and sludge — Determination of total organic carbon (TOC) by dry combustion

Step-by-step procedure

1. Status and edition

   PKN card: PN-EN 15936:2022-07 current (English version); edition 2013-02 withdrawn on 20-07-2022 (state of the cards on 29 September 2026). In the scopes AB 1267 still cites edition 2013-02.

2. Choice of method

   Method A (difference) or B (direct); the report states the letter — in accreditation scopes four laboratories do not give it at all (AB 054, AB 313, AB 418, AB 550), and AB 005 and AB 213 give it for only one of three entries.

3. Sample preparation

   Procedure NOT GIVEN.

4. Combustion and measurement

   Dry combustion; in the scopes — most often high-temperature combustion with infrared detection.

5. Result and assessment

   TOC in % of dry matter (or mg/kg, g/kg); for waste — comparison with the criteria of the regulation on accepting waste for landfilling.

Required equipment and apparatus

Reagents, media and consumables

Health and safety (OHS)

• Work with a high-temperature combustion furnace and, for inorganic carbon, with acid; the analyser manual and the safety data sheets of the reagents used apply
• SUBSTANTIVE NOTE: the card allows other solid environmental matrices only if the user verifies the applicability of the method — for fuels, plastics, construction materials or fertilisers it is worth asking the laboratory about this verification

Frequently asked questions