🌿 Chromium(VI) compounds in workplace air — filter, leaching with sodium carbonate solution, reaction with diphenylcarbazide, colorimetry; standard withdrawn in 2014, NDS 0.005 mg/m³ Cr(VI), PN-Z-04126-03

Environment PN-87/Z-04126/03

Overview

WHAT THE STANDARD COVERS. Scope from the PKN card, in full (our translation): "The method allows the determination of soluble chromates and chromium (VI) compounds in complex mixtures, e.g. in welding fumes. A content of 100 micrograms of chromium (III) and 200 micrograms of iron in the sample does not interfere with the determination. The method consists in taking the sample on a paper filter, leaching chromium (VI) with sodium carbonate solution, acidifying the solution and removing the carbon dioxide released, and reacting the chromium with diphenylcarbazide in an acidic medium. The red-violet colour of the resulting complex compound is determined colorimetrically. The determinability, expressed as chromium trioxide, is 0.004 mg per 1 cubic metre of air" (without a full stop at the end on the card). Expressed as chromium this is about 0.0021 mg/m³ (our conversion: 0.004 × 52.00 / 100.0 — molar masses of Cr and CrO₃). The card does not give the air volume and flow, the wavelength, the calibration or the precision. We did not have the text of the standard (2 pages).

LIMIT VALUES. According to the regulation of the Minister of Family, Labour and Social Policy of 26 March 2026 (Journal of Laws 2026, item 447, annex, item 582), for chromium(VI) compounds — expressed as Cr(VI) — the NDS is 0.005 mg/m³; the list gives no NDSCh for them. For comparison: chromium metal and chromium(II) and chromium(III) compounds have separate entries in the list (item 120).

STATUS (state of the cards on 30 September 2026). The card of PN-Z-04126-03:1987 (Polish version) has the header "Withdrawn": published 07-09-1987, "Withdrawal date: 30-05-2014", 2 pages, price group A, Health, Environment and Medicine Sector, KT 159 for Chemical and Dust Hazards in the Working Environment, ICS 13.040.30; a national standard, without "Introduces" and "Replaced by" fields. The PKN search for "PN-Z-04126" (30 September 2026) shows six items: sheets 00:1979 (general provisions), 01:1979 ("Withdrawn and replaced by PN-Z-04434:2011" — chromium and its compounds by flame atomic absorption spectrometry, described in the Knowledge Base in a separate entry), 02:1987, 03:1987 and 5:1994 — all withdrawn — and the current PN-Z-04434:2011. Sheet 02:1987 is the variant "with acid extraction of the sample" — according to the card: soluble chromates and chromic acid, paper or membrane filter, leaching of chromium(VI) with sulphuric acid solution with potassium permanganate as oxidant, reaction with diphenylcarbazide; chromium(III) and large amounts of copper(II), nickel(II), vanadium(V) and iron(III) interfere; determinability 0.02 mg/m³ expressed as chromium trioxide; withdrawal date 27-11-2012; it replaced PN-Z-04055:1971. Sheet 5:1994 concerned chromium in suspended particulate matter in ambient air (atomic absorption spectrometry; withdrawal date 13-11-2025), and 00:1979 — general provisions (withdrawal date 23-08-2007). The PKN search for "chromu(VI)" and for "chromu sześciowartościowego" (hexavalent chromium, 30 September 2026) gives 144 items each, because it matches the single word "chromu"; on the first page (50 items) chromium(VI) appears in the title only in the two withdrawn sheets of this series and in the withdrawn PN-P-22108:2000 (tanned leather), and the current PN-Z-04434:2011 (total chromium) is in first place. For "16740" the catalogue shows only PN-EN 16740:2016-02 on air fresheners — ISO 16740:2005, which AB 1207 cites for chromium(VI) in workplace air, has no Polish edition in the catalogue.

HOW MANY LABORATORIES AND IN WHAT FORM (copy of the accreditation-scope database, data loaded up to 17 September 2026, read on 30 September 2026). All notations of number 04126-03: 12 entries at 11 laboratories — the same number of occurrences in the current PCA documents; AB 1004 has two entries (workplace air and waste gases — "excluding point 7"). Notations: "PN-87/Z-04126/03" — 7 laboratories (AB 409, AB 481, AB 647, AB 869, AB 882, AB 934, AB 1144), "PN-Z-04126-03:1987" — AB 877 and AB 1642, "PN-87/Z-04126-03" — AB 888, "PN-87/Z-04126.03" — AB 1004. In the same entry alongside the standard — NIOSH 7600:2015 (AB 882) and instruction IB-140 issue 1 of 25.11.2024 (AB 934). The "Laboratories" tab looks for notations that BEGIN with "PN-87/Z-04126/03" (the form used in the scopes, the most frequent one) and will show 7 of the 11 laboratories — checked with the tab's query on the production server labcoda.pl on 30 September 2026: 7; it will not show AB 877, AB 888, AB 1004 and AB 1642, and the PKN catalogue form "PN-Z-04126-03" would give 2. Current scopes on the PCA website (read on 30 September 2026, issues from 08.01.2026 to 03.09.2026): all entries are in the issues in force, each of the 19 pairs of range figures from the copy appears in the current document and no entry is suspended.

MATRIX, TECHNIQUE AND RANGES. Workplace air — 10 laboratories (AB 934 also ambient and indoor air); AB 877 — air and waste-gas samples collected on filters (general environment), AB 1004 — also waste gases. Technique — everywhere "spectrophotometric method". Name of the measured quantity: "chromium (VI) compounds expressed as Cr (VI)" at most laboratories, "chromates (VI) and dichromates (VI)" at AB 647 and AB 877, "chromium VI" at AB 1004. Concentration ranges in workplace air (8 laboratories; AB 869 and AB 877 give only the mass in the sample, AB 409 — no range): lower limits from 0.00037 mg/m³ (AB 1144), 0.00041 mg/m³ (AB 882) and 0.000417 mg/m³ (AB 934) through 0.0005 mg/m³ (AB 481, AB 1642) and 0.002 mg/m³ (AB 1004) to 0.006 mg/m³ (AB 647, AB 888); upper limits from 0.023 mg/m³ (AB 882) and 0.027 mg/m³ (AB 1642) to 0.5 mg/m³ (AB 888), 0.6 mg/m³ (AB 647) and 1.6 mg/m³ (AB 1004).

ALONGSIDE THIS STANDARD. Chromium(VI) compounds in workplace air without this sheet are determined by 17 laboratories: according to the withdrawn sheet 02:1987 (acid extraction; notation "PN-87/Z-04126/02" or ".02") — AB 340 ((0.0016 – 0.314) mg/m³), AB 484 ((0.00038 – 0.011) mg/m³), AB 802 ((0.000417 – 0.6) mg/m³), AB 849 ((0.0004 – 0.05) mg/m³), AB 1184 (with instruction IK-804, (0.001 – 0.2) mg/m³) and AB 1257 ((0.001 – 0.050) mg/m³) — all with a lower limit below the determinability of that sheet on its card (0.02 mg/m³ as CrO₃, about 0.0104 mg/m³ as Cr); according to NIOSH method 7600 (issue 3, 2015) — AB 343 (two entries), AB 647 (from 0.00028 mg/m³), AB 719 (with instruction PA-56), AB 869, AB 875, AB 886 and AB 1364, and AB 882 — in the same entry as sheet 03; according to the method from the quarterly "Podstawy i Metody Oceny Środowiska Pracy" 2018, no. 3 (97), pp. 131–148 (ion chromatography with spectrophotometric detection) — AB 418, AB 632, AB 1207 (together with ISO 16740:2005) and AB 1854. None of these rows is suspended (current PCA documents, read on 30 September 2026). Total chromium — chromium metal and chromium(II), (III) and (VI) compounds expressed as Cr — is determined according to PN-Z-04434:2011 (a separate entry in the Knowledge Base); a total-chromium result is not a chromium(VI) result.

WHERE A SEEMINGLY CORRECT RESULT IS EASY TO GET. First — the lower limit against the NDS: the NDS for chromium(VI) compounds is 0.005 mg/m³, and AB 647 and AB 888 start the range under this standard at 0.006 mg/m³ — a result "below 0.006 mg/m³" does not show whether the concentration is below the NDS (AB 647 has a separate entry for low concentrations under NIOSH 7600, from 0.00028 mg/m³). Second — the conversion: the card gives the determinability expressed as chromium trioxide (0.004 mg/m³), while the NDS is expressed as Cr(VI) — the same figure in the two conversions differs almost twofold (about 0.0021 mg/m³ as Cr). Third — what the method measures: the card speaks of soluble chromates and chromium(VI) compounds in complex mixtures, leached from the filter with sodium carbonate solution; whether this covers all forms of chromium(VI) present in the dust examined does not follow from the card — ask the laboratory. Fourth — status and notation: the standard has been withdrawn since 2014 and appears under four forms of the designation, so the tab shows 7 of the 11 laboratories.

WHAT WE DO NOT GIVE. We did not have the text of the standard — PKN sells it (2 pages). We do not give the type and diameter of the filter, the air volume and flow, the concentrations of the sodium carbonate and diphenylcarbazide solutions, the acidification procedure, the wavelength, the calibration curve, the formula or the precision.

Method principle

According to the PKN card, aerosol from workplace air is collected on a paper filter, chromium(VI) is leached with sodium carbonate solution, the solution is acidified and freed of the carbon dioxide released, and chromium(VI) forms a red-violet complex with diphenylcarbazide in an acidic medium, whose colour is measured colorimetrically. 100 µg of chromium(III) and 200 µg of iron in the sample do not interfere. We DO NOT GIVE the sampling and measurement conditions — we did not have the text of the standard.

Applications

• Chromium(VI) compounds — soluble chromates, also in complex mixtures such as welding fumes — in workplace air, in the scopes of 10 laboratories (NDS 0.005 mg/m³ expressed as Cr(VI))
• Air and waste-gas samples collected on filters — AB 877; waste gases — second entry of AB 1004 (excluding point 7)

Key parameters

Standard

Standard number

PN-Z-04126-03:1987 (wersja polska; norma wycofana)

Title (PL)

Ochrona czystości powietrza — Badania zawartości chromu i jego związków — Oznaczanie chromu sześciowartościowego na stanowiskach pracy metodą kolorymetryczną z alkaliczną ekstrakcją próbki

Title (EN)

Air purity protection — Tests for chromium and its compounds content — Determination of hexavalent chromium at workplaces by colorimetric method with alkaline extraction of the sample

Step-by-step procedure

1. Status of the document

   PKN card: PN-Z-04126-03:1987 withdrawn on 30-05-2014, no successor on the card (state of the card on 30 September 2026).

2. Sampling

   Aerosol from workplace air onto a paper filter; we DO NOT GIVE the volume and flow.

3. Leaching and preparation

   Chromium(VI) is leached with sodium carbonate solution, the solution is acidified and the carbon dioxide released is removed (PKN card).

4. Colour reaction and measurement

   Chromium(VI) with diphenylcarbazide in an acidic medium — red-violet complex, colorimetric measurement; 100 µg Cr(III) and 200 µg Fe in the sample do not interfere.

5. Result

   Concentration expressed as Cr(VI) for comparison with the NDS of 0.005 mg/m³ — note: the determinability on the card is expressed as CrO₃; we DO NOT GIVE the formula.

Required equipment and apparatus

Reagents, media and consumables

Health and safety (OHS)

• Chromium(VI) compounds are carcinogenic — standard solutions and samples are prepared under a fume hood, wearing gloves, and waste is collected as hazardous; the card does not name the reference substance
• TECHNICAL NOTE: with an NDS of 0.005 mg/m³ the laboratory range must start below the NDS — a range from 0.006 mg/m³ does not make it possible to demonstrate compliance

Frequently asked questions