🌿 n-Hexane in workplace air — adsorption on activated charcoal and gas chromatography, PN-Z-04136-3

Environment PN-Z-04136-3

Overview

WHAT THE STANDARD COVERS. The scope from the PKN catalogue card, quoted in full: "A method is given consisting in adsorption of n-hexane vapour on activated charcoal, desorption of the compound with carbon disulphide and analysis of the resulting solution by gas chromatography. The lowest concentration of n-hexane that can be determined by this method is 10 mg/m3." The standard concerns n-hexane — the straight-chain isomer — and not all hexanes.

STATUS (state of the card on 28 September 2026). The card has no withdrawal note and no "Superseded by" field — the standard is CURRENT. The card has no "Supersedes" field. Edition: published 28-10-2003, 5 pages, KT 159 (Chemical and Dust Hazards in the Working Environment), ICS 13.040.30.

THE LIMIT VALUE AND ITS TWO ROWS. The Polish NDS list as worded by the regulation of 26 March 2026 (Journal of Laws 2026, item 447): item 289 "Heksan" (hexane) [110-54-3] — NDS 72 mg/m³, no NDSCh, "skin" notation; a separate row, item 293 "Heksanu izomery acykliczne nasycone, z wyjątkiem heksanu:" (acyclic saturated isomers of hexane, except hexane: 2,2-dimethylbutane, 2,3-dimethylbutane, 3-methylpentane, 2-methylpentane) — NDS 400 mg/m³, NDSCh 1200 mg/m³; the "hexane" of item 289 is n-hexane [110-54-3]. The standard determines n-hexane, so its result is assessed against 72 mg/m³. The lowest determinable concentration according to the card — 10 mg/m³ — is about one seventh of that value. According to the footnote of the list, the "skin" notation means that "absorption of the substance through the skin may be as important as exposure by inhalation" — measuring the concentration in air does not cover that route.

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 04136 with sheet 3: 20 entries at 16 laboratories. Forms: "PN-Z-04136-3:2003" — 14 laboratories (17 entries) and "PN-Z-04136-03:2003" with a zero before the sheet number — 2 laboratories (AB 647, AB 882; 3 entries). The "Laboratories" tab searches for records BEGINNING with "PN-Z-04136-3" and will show 14 laboratories; AB 647 and AB 882 remain outside it.

TECHNIQUE AND TEST OBJECT IN THE SCOPES. Every one of the 16 laboratories records gas chromatography with a flame ionisation detector (GC-FID); AB 882 has an additional entry with mass spectrometric detection (GC-MS), and AB 591 gives no technique for the entry with a "calculated" concentration. Two laboratories go beyond n-hexane and beyond the workplace: AB 719 cites the standard also for pentane (together with its own procedure and clause 8 of the standard alone), and AB 1168 — for waste-gas samples taken on sorbent tubes. AB 719 describes the samples as taken "on sorbent tubes with activated charcoal or silica gel", although the card speaks only of activated charcoal.

THE METHOD LIMIT AND THE LABORATORIES' RANGES — A PLACE FOR A SEEMINGLY CORRECT RESULT. Card: lowest determinable concentration 10 mg/m³. A range in mg/m³ is given by 14 laboratories, and ALL declare a lower limit below it: from 0.062 mg/m³ (AB 746), 0.10 mg/m³ (AB 1642) and 0.17 mg/m³ (AB 886) to 7.2 mg/m³ (AB 632). Upper limits: from 111.1 mg/m³ (AB 1168) to 4309 mg/m³ (AB 882). Four laboratories cite the standard together with their own procedure or instruction (AB 300, AB 562, AB 719, AB 882). For the mass of hexane in the sample AB 591 excludes clauses 8 and 13 of the standard, and for the concentration in air, marked "calculated", it cites precisely these. What the limits lower than the card's value result from — WE HAVE NOT ESTABLISHED; a result below 10 mg/m³ described only by the number of the standard does not show how the laboratory went below the method limit.

OTHER DOCUMENTS FOR THE SAME DETERMINATION. For hexane in workplace air the scopes also cite methods from the quarterly "Podstawy i Metody Oceny Środowiska Pracy" (Principles and Methods of Assessing the Working Environment): No 1(67) of 2011, pp. 35–44 (AB 522, AB 1207, AB 1854 — each with its own procedure; at AB 522 the item is suspended at the laboratory’s request until 14 February 2027) and No 1(51) of 2007, pp. 141–147 (AB 565, in a combined item for organic compounds). The method "NIOSH Method 1500 Issue 3 (2003)" is cited by AB 1226, in a single item together with n-heptane (n-hexane 5.0–200 mg/m³ and 0.03–1.2 mg per sample, GC-FID; PCA scope issue 26 of 17 September 2026, p. 6/18 — item suspended at the laboratory’s request from 10 June 2026 to 7 December 2026). The method from issue 17 of 1997, pp. 69–73, is cited by AB 300, AB 632 and AB 1207 for the acyclic isomers of hexane — i.e. for the second row of the list (NDS 400 mg/m³), not for n-hexane. We did not compare their content with the standard.

WHAT WE DO NOT GIVE. We did not have the text of the standard — PKN supplies it for a fee (5 pages). We do not give the air volume and flow rate, the amount of activated charcoal, the desorption and chromatographic conditions, the formula or the precision. What clauses 8 and 13 contain — WE HAVE NOT ESTABLISHED.

Method principle

According to the card: n-hexane vapour from workplace air is adsorbed on activated charcoal, the compound is desorbed with carbon disulphide, and the resulting solution is analysed by gas chromatography. The lowest concentration of n-hexane determinable by this method according to the card: 10 mg/m³. The result is assessed against the n-hexane NDS of 72 mg/m³ (no NDSCh, "skin" notation). We DO NOT GIVE the sampling and chromatographic conditions — we did not have the text of the standard.

Applications

• Measurements of n-hexane in workplace air — assessment against NDS 72 mg/m³ (Journal of Laws 2026, item 447, item 289 of the list)
• Not for a mixture of hexanes: the other acyclic isomers of hexane have a separate row of the list (NDS 400 mg/m³, NDSCh 1200 mg/m³)
• In accreditation scopes, singly also pentane (AB 719) and waste-gas samples (AB 1168)

Key parameters

Standard

Standard number

PN-Z-04136-3:2003 (wersja polska)

Title (PL)

Ochrona czystości powietrza — Badania zawartości heksanu — Oznaczanie n-heksanu na stanowiskach pracy metodą chromatografii gazowej

Title (EN)

Air purity protection — Tests for hexane content — Determination of n-hexane at workplaces by gas chromatography

Step-by-step procedure

1. Status of the document

   PKN card: standard current (state of the card on 28 September 2026). In the report give the full designation: PN-Z-04136-3:2003.

2. Air sampling

   n-Hexane vapour is adsorbed on activated charcoal. Air volume and flow rate NOT GIVEN.

3. Desorption

   n-Hexane is desorbed from the activated charcoal with carbon disulphide.

4. Chromatographic determination

   The solution is analysed by gas chromatography. Conditions NOT GIVEN.

5. Result and assessment

   The concentration in mg/m³ is compared with NDS 72 mg/m³. A result below 10 mg/m³ lies below the method limit given on the card — check how the laboratory lowered it.

Required equipment and apparatus

Reagents, media and consumables

Health and safety (OHS)

• Carbon disulphide and n-hexane are extremely flammable — solutions are prepared in a fume cupboard, away from ignition sources; safety data sheets apply
• n-Hexane carries the "skin" notation in the NDS list — in exposure assessment the air measurement alone does not cover absorption through the skin
• TECHNICAL NOTE: the "Hexane" row (NDS 72 mg/m³) and the row for acyclic isomers (NDS 400 mg/m³) are two different values — the result of this standard concerns n-hexane

Frequently asked questions