🌿 Determination of about 70 elements (among others As, Cd, Cr, Cu, Hg, Ni, Pb, Zn, P, S, rare earth elements and platinum group metals) in aqua regia or nitric acid digests of sewage sludge, treated biowaste and soil by inductively coupled plasma mass spectrometry (ICP-MS) — corrections of isobaric and molecular interferences, internal standard, dilution on signal suppression; detection limit 0.1–2.0 mg/kg d.m.; standard withdrawn by PKN on 05.03.2026 and replaced by PN-EN ISO 16965:2026-03, PN-EN 16171

Environment PN-EN 16171

Overview

WHAT THE STANDARD COVERS. The scope on the PKN catalogue card of PN-EN 16171:2017-02 (English version) begins (our translation): “This European Standard specifies a method for the determination of the following elements in extracts of sewage sludge, treated biowaste and soil obtained with aqua regia or nitric acid”; the card then lists the elements and detection limits as Clause 1 of the standard does (description below). We read the text of the standard in the iTeh sample of SIST EN 16171:2017 (text of EN 16171:2016, English): from the title page through the contents, European foreword, introduction and Clauses 1–4 up to and including 5.6 of Clause 5 (reagents). Outside the sample remain the further subclauses of Clause 5, Clauses 6 (apparatus), 7 (solutions, instrument set-up, linear and standard addition calibration, correction factors, variable isotope ratios, measurement), 8–9 (calculation, expression of results), 10 (performance characteristics — blank, calibration check, internal standard response, interferences, recovery), 11 (test report) and Annexes A (repeatability and reproducibility) and B (isotopes and interferences for quadrupole instruments).

ACCORDING TO THE TEXT OF EN 16171:2016 (Clauses 1–4, 5.1–5.6). The standard was prepared by CEN/TC 444 “Test methods for environmental characterization of solid matrices” (secretariat NEN); CEN approved it on 19 March 2016; it replaced CEN/TS 16171:2012, adding data from a European interlaboratory comparison organised in 2013 by BAM; the previous edition was based on European Commission mandate M/330 (methods for sludge, treated biowaste and soil). Validation (Table 1): municipal sludge, compost, soil. Scope (1): Al, Sb, As, Ba, Be, Bi, B, Cd, Ca, Ce, Cs, Cr, Co, Cu, Dy, Er, Eu, Gd, Ga, Ge, Au, Hf, Ho, In, Ir, Fe, La, Pb, Li, Lu, Mg, Mn, Hg, Mo, Nd, Ni, Pd, P, Pt, K, Pr, Re, Rh, Rb, Ru, Sm, Sc, Se, Si, Ag, Na, Sr, S, Te, Tb, Tl, Th, Tm, Sn, Ti, W, U, V, Yb, Y, Zn, Zr in aqua regia or nitric acid digests; the working range depends on the matrix and interferences; method detection limit for most elements — 0.1–2.0 mg/kg dry matter, higher with interferences or memory effects; the method is validated for the elements in Tables A.1–A.3, and applicable to the others after verification by the user. References (2): EN 15934 (dry matter), EN 16173 (nitric acid digestion), EN 16174 (aqua regia digestion), EN ISO 3696, EN ISO 17294-1:2006. Principle (3): digests according to EN 16173 or EN 16174 are nebulised, the aerosol is carried by argon into the plasma, ions pass through an interface into a mass spectrometer, are separated by m/z and counted by a detector; for tin only aqua regia digestion applies (EN 16174). Interferences (4): they shall be assessed and corrected, including background ions from the plasma gas, reagents and matrix (details — EN ISO 17294-1:2006, Clause 6). Isobaric elemental (4.2.1) — isotopes of different elements with the same nominal mass, e.g. 114Cd and 114Sn; corrected by taking the interfering element into account, with correction isotopes free of interference where possible (common ones — Table B.1). Molecular and doubly charged ions (4.2.2) — e.g. 40Ar35Cl+ and 40Ca35Cl+ on 75As, 98Mo16O+ on 114Cd; corrections assuming a constant fraction of the molecular ion have proved unreliable because oxide levels depend on operating conditions — the coefficient from measuring the interference solution is determined just before the sequence and checked during it; alternatives are a collision/reaction cell or high-resolution ICP-MS; correction is mandatory when the impact may exceed three times the detection limit or half the lowest concentration reported. Non-spectral (4.2.3) — changes of viscosity and surface tension, signal suppression or enhancement, deposits on the nebuliser and cones; total dissolved solids below 0.2 % (2000 mg/l) are recommended; an internal standard matched to the analyte, matrix matching (especially acid concentration) or standard addition; a drop of the internal standard signal below 30 % of the signal in the calibration solution indicates intolerable interference — usually removed by dilution (e.g. fivefold). Reagents (5): purity adequate for trace determinations; water of grade 1 according to EN ISO 3696; nitric acid ρ = 1.4 g/ml (15 mol/l); hydrochloric acid ρ = 1.18 g/ml (12 mol/l); single- and multi-element stock solutions (e.g. 1000 mg/l), preferably preserved with nitric acid to limit chlorine interferences — Bi, Hf, Hg, Mo, Sn, Sb, Te, W and Zr may need hydrochloric acid; stable more than a year, taking the manufacturer’s recommendations into account; anion solutions Cl−, PO43−, SO42− at 1000 mg/l each; when combining multi-element solutions, chemical compatibility, hydrolysis and precipitation must be considered.

STATUS (cards as of 03.10.2026). The card of PN-EN 16171:2017-02 (English version, published 07-02-2017, 27 pages, price group N) has the header “Withdrawn”: withdrawal date 05-03-2026, Health, Environment and Medicine Sector, KT 216 Waste, ICS 13.030.01 and 13.080.10, “Introduces: EN 16171:2016 [IDT]”, “Replaced by: PN-EN ISO 16965:2026-03 — English version”. The successor (card of PN-EN ISO 16965:2026-03, English version, published 05-03-2026, 30 pages, KT 191 Soil Chemistry, “Introduces: EN ISO 16965:2025 [IDT], ISO 16965:2025 [IDT]”, “Replaces: PN-EN 16171:2017-02”) has no “Withdrawn” header. According to the successor’s “Scope” field, what the result refers to has changed: the same list of elements, but in digests of soil, treated biowaste, WASTE, sewage sludge and SEDIMENTS, obtained with aqua regia, nitric acid OR a mixture of hydrochloric, nitric and tetrafluoroboric or hydrofluoric acid, and also in eluates from construction products (EN 17200). We have not read the successor’s text beyond the “Scope” field, so we do not know whether the measurement requirements have changed. In the iTeh catalogue (read on 03.10.2026) EN 16171:2016 has the status “Withdrawn” (withdrawal date 30.09.2026) and the field “Replaced By: EN ISO 16965:2025”, and the Slovenian SIST EN 16171:2017 — “Withdrawn” since 13.02.2026. The nitric acid digestion standard cited by this standard is described in a separate entry on PN-EN 16173; PKN withdrew the aqua regia digestion standard PN-EN 16174:2012 on 30.03.2022 (card of PN-EN 16174:2012, as of 03.10.2026 — without a “Replaced by” field; the entry “Aqua regia digestion of soil, treated biowaste, sewage sludge and waste before the determination of metals and other elements — heating under reflux (A1), in a heating block (A2) or by microwave in closed vessels at 175 °C (B), PN-EN ISO 54321” describes its successor).

HOW MANY LABORATORIES AND IN WHAT FORM (copy of the accreditation scope database, data up to 17.09.2026, read on 03.10.2026). The number 16171 appears in 11 records at 4 laboratories: AB 085, AB 213, AB 322, AB 680. In the current PCA documents (read on 03.10.2026, issues from 21.10.2025 to 17.04.2026) the number appears in 11 items of the same 4 laboratories (AB 085 and AB 680 4 each, AB 213 — 2, AB 322 — 1). Notation everywhere “PN-EN 16171:2017-02”; in two items of AB 085 it stands in second place, after the digestion standard (PN-EN 16173:2012 or PN-EN 16174:2012). All PCA documents were issued before the date of withdrawal of the standard by PKN (05.03.2026) or shortly after it (AB 213 — 17.04.2026); none of them cites PN-EN ISO 16965. The “Laboratories” tab (“PN-EN 16171”) shows the same 4 laboratories — checked with the tab query on the production server labcoda.pl on 03.10.2026; in the database copy 9 of the 11 records fall under this prefix (two begin with the digestion standard).

WHAT THE LABORATORIES TEST (items in PCA). All items — ICP-MS. AB 085 — soil: elements (among others As, Cr, Cd, Co (0.2–400) mg/kg, Ba, Zn, Cu (2.0–400) mg/kg) after nitric acid digestion according to PN-EN 16173 and tin (2.0–400) mg/kg after aqua regia digestion according to PN-EN 16174 — as the note to Clause 3 provides; sewage sludge and waste with code 19 08 05 — elements and calcium ((0.2–200) g/kg) and magnesium. AB 680 — metals (Pb, Cu, Cd, Zn, Cr, Ni) in soil, in soil improvers, in sewage sludge (e.g. Zn (2.5–10000) mg/kg) and in waste with codes 19 05 03 and 19 05 99. AB 322 — total phosphorus in sewage sludge, (0.3–8.0) % (3.0–80 g/kg). AB 213 — elements in soil and in construction waste with codes 17 01 01…17 05 08 (among others antimony (2.0–500) mg/kg, barium (1.0–5000) mg/kg), in both items together with PN-EN ISO 17294-2 and PN-EN 13657, and in soil also with PN-ISO 11466. Waste and soil improvers lie outside the scope of PN-EN 16171 (sludge, biowaste, soil) — waste is covered only by the successor.

WHERE A SEEMINGLY CORRECT RESULT IS EASY. With cadmium: 114Cd overlaps with 114Sn and the 98Mo16O+ ion (4.2.1, 4.2.2) — in soil or sludge rich in tin or molybdenum an uncorrected signal raises cadmium. With arsenic: 40Ar35Cl+ and 40Ca35Cl+ ions fall on 75As (4.2.2) — an aqua regia digest (much chlorine) and a calcium-rich sample raise arsenic if there is no correction or collision cell. With corrections: an oxide coefficient carried over from another day does not fit, because oxide levels depend on operating conditions — the standard requires determining it just before the sequence (4.2.2). With the matrix: an internal standard signal below 30 % of the signal in the calibration solution means intolerable interference, not a result to be corrected (4.2.3). With tin: a nitric acid digest is not suitable for tin — only aqua regia (3, note). With the result: the content refers to the portion soluble in the acid used, not the total, and results after aqua regia and after nitric acid are not the same result.

WHAT WE DO NOT GIVE. We have not read Clauses 6–11 or the annexes, so we do not give the instrument operating conditions, the choice of isotopes and internal standards, the calibration, calculations, criteria for recovery and calibration checks or precision data. Nor do we say how the successor PN-EN ISO 16965 differs in measurement requirements — we have not read its text beyond the “Scope” field of the card — or requirements of regulations on sewage sludge and soil.

Method principle

A digest of sludge, biowaste or soil obtained with aqua regia (EN 16174) or nitric acid (EN 16173) is nebulised, and the aerosol is carried by argon into an inductively coupled plasma; the ions formed pass through an interface into a mass spectrometer, are separated by mass-to-charge ratio and counted by a detector. The concentration is determined from calibration (linear or standard addition) with an internal standard, after correction of isobaric, molecular and non-spectral interferences, and converted to the dry matter of the sample.

Applications

• Sewage sludge, treated biowaste and soil — about 70 elements in aqua regia or nitric acid digests, detection limit 0.1–2.0 mg/kg d.m. for most (1)
• Tin — only after aqua regia digestion (3, note)
• Soil, sewage sludge, soil improvers and waste — metals and phosphorus by ICP-MS in the accreditation scopes of 4 laboratories in PCA

Key parameters

Standard

Standard number

PN-EN 16171:2017-02

Title (PL)

Osady ściekowe, uzdatnione bioodpady oraz gleba — Oznaczanie zawartości pierwiastków z zastosowaniem spektrometrii mas z plazmą wzbudzoną indukcyjnie (ICP-MS)

Title (EN)

Sludge, treated biowaste and soil — Determination of elements using inductively coupled plasma mass spectrometry (ICP-MS)

Step-by-step procedure

1. Sample solution

   Digestion with nitric acid (EN 16173) or aqua regia (EN 16174; tin — aqua regia only). PN-EN 16171:2017-02 WITHDRAWN 05.03.2026, successor PN-EN ISO 16965:2026-03 (PKN cards as of 03.10.2026).

2. Instrument set-up and calibration

   Linear or standard addition calibration, internal standard; we do not give the details (Clause 7).

3. Interference corrections

   Correction coefficients determined just before the sequence and checked during it; correction mandatory when the impact may exceed 3 × LOD or half the lowest concentration reported.

4. Measurement

   Check of the internal standard signal — below 30 % of the calibration signal dilute the sample (e.g. 5 ×); dissolved solids below 0.2 %.

5. Result

   In mg/kg dry matter (dry matter according to EN 15934), as the portion soluble in the acid used.

Required equipment and apparatus

Reagents, media and consumables

Health and safety (OHS)

• Concentrated nitric and hydrochloric acids — work in a fume hood, eye and hand protection
• Argon plasma and high voltage of the instrument — operation according to the manufacturer’s instructions
• The standard requires tests to be carried out by suitably trained staff and the user to establish safety practices (warning in the introduction)

Frequently asked questions