🌿 Trimethylbenzene in workplace air — activated charcoal and gas chromatography, PN-Z-04016-4

Environment PN-Z-04016-4

Overview

WHAT THE STANDARD COVERS. The scope from the PKN catalogue card, quoted in full: "The method consists in adsorption of trimethylbenzene vapour on activated charcoal, extraction with carbon disulphide and chromatographic analysis of the resulting solution. The lowest concentration of trimethylbenzene that can be determined by this method is 10 mg/m3." The title speaks of gas chromatography and places the standard in the series on "benzene and its homologues with a saturated side chain" — the same series PN-Z-04016 includes, among others, sheet 10 on benzene, which has a separate entry in this knowledge base.

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 The card has no withdrawal note and no "Superseded by" field — the standard is CURRENT.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 07-09-1998, 6 pages, KT 159 (Chemical and Dust Hazards in the Working Environment), ICS 13.040.30.

THE LIMIT VALUE — ONE FOR THE MIXTURE AND FOR EACH ISOMER. The Polish NDS list as worded by the regulation of 26 March 2026 (Journal of Laws 2026, item 447), item 553 "Trimethylbenzene – mixture of isomers (1,2,3-; 1,2,4-; 1,3,5-)" [526-73-8; 95-63-6; 108-67-8; 25551-13-7]: NDS 100 mg/m³, NDSCh 170 mg/m³, "skin" notation. The note at the end of the list settles the question most often asked about this substance: "If the NDS concerns a mixture of isomers, then where one of them occurs in the working environment the same NDS value shall be applied." The lowest determinable concentration according to the card — 10 mg/m³ — is one tenth of the NDS. According to the footnote of the list, the "skin" notation means that absorption through the skin may be as important as the respiratory route — a measurement in air does not cover it.

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 04016 with sheet 4: 28 entries at 15 laboratories, all in the single form "PN-Z-04016-4:1998". The "Laboratories" tab searches for records BEGINNING with "PN-Z-04016-4" and will show all 15 laboratories in 28 entries — for this standard the tab and the measurement say the same. Among these 28 entries, one scope row of AB 886 (three isomers and the mixture) is split into four entries in the database, and one row of AB 1144 into two. SUSPENSION: in the current PCA scope of AB 522 (issue 26 of 18 August 2026) both items of this standard are suspended at the laboratory’s request from 18 August 2026 to 14 February 2027 (footnote "*)" at items set in bold italics; read on 29 September 2026). The numbers above include them.

MIXTURE OR ISOMERS — HOW THE LABORATORIES RECORD IT. Twelve laboratories name all three isomers (1,2,3-, 1,2,4- and 1,3,5-trimethylbenzene): seven as separate determinations (AB 632, AB 869, AB 886, AB 1144, AB 1207, AB 1642, AB 1854; AB 1642 and AB 1854 also give the sum), five in the name of the mixture (AB 300, AB 522, AB 562, AB 581, AB 882). AB 340 writes "trimethylbenzene (isomers)", AB 746 — "trimethylbenzene", and AB 622 — "mixture of isomers (1,2,4-)", i.e. with a single isomer. Technique: gas chromatography with a flame ionisation detector (GC-FID) — 14 laboratories; with mass spectrometry (GC-MS) — AB 882 (alongside GC-FID) and AB 1207 (exclusively, in an entry on volatile organic compounds).

THE METHOD LIMIT AND THE LABORATORIES' RANGES. A range in mg/m³ is given by 13 laboratories. Lower limits: from 0.067 mg/m³ (AB 1642), 0.17 mg/m³ (AB 886, AB 1207) and 0.52 mg/m³ (AB 522 — item suspended until 14 February 2027) to 10 mg/m³ (AB 632) — twelve of the thirteen below the card's 10 mg/m³; only AB 632 declares a limit equal to the card. Upper limits: from 314 mg/m³ (AB 622) to 4666 mg/m³ (AB 340). Six laboratories cite the standard together with their own procedure or instruction (AB 300, AB 522, AB 562, AB 882, AB 1207, AB 1854). What the limits lower than the card's value result from — WE HAVE NOT ESTABLISHED.

OTHER DOCUMENTS FOR THE SAME DETERMINATION. For trimethylbenzenes in workplace air the scopes also cite the method from the quarterly "Podstawy i Metody Oceny Środowiska Pracy" (Principles and Methods of Assessing the Working Environment) 2007, No 1(51), pp. 141–147: AB 565 — in a combined item for organic compounds, three isomers (0.02–10 mg per sample, with the concentration of 0.023–450 mg/m³ "calculated"; PCA scope issue 28 of 3 November 2025), and AB 1226 — in a single item together with styrene, cyclohexane, cyclohexanone and butan-2-one (1,2,3-trimethylbenzene 9–4330 mg/m³, the 1,2,4- and 1,3,5-isomers 10–4767 mg/m³; issue 26 of 17 September 2026, p. 10/18 — item suspended at the laboratory’s request from 10 June 2026 to 7 December 2026). Apart from these, the copy holds for trimethylbenzenes only this standard, the laboratories’ own procedures and the general entry "Normy, Procedury badawcze" (Standards, test procedures; AB 934; PCA scope issue 32 of 3 July 2026, p. 28/41). We did not compare the content of the quarterly method with the standard.

WHAT WE DO NOT GIVE. We did not have the text of the standard — PKN supplies it for a fee (6 pages). We do not give the air volume, the amount of activated charcoal, the extraction and chromatographic conditions, the way the isomers are separated, the formula or the precision.

Method principle

According to the card: trimethylbenzene vapour from workplace air is adsorbed on activated charcoal, extracted with carbon disulphide, and the resulting solution is analysed by gas chromatography. Lowest determinable concentration according to the card: 10 mg/m³. The result is assessed against the NDS of 100 mg/m³ and NDSCh of 170 mg/m³ — the same for the mixture of isomers and for each isomer separately. We DO NOT GIVE the sampling and chromatographic conditions — we did not have the text of the standard.

Applications

• Measurements of trimethylbenzene in workplace air — assessment against NDS 100 mg/m³ and NDSCh 170 mg/m³ (Journal of Laws 2026, item 447, item 553 of the list)
• Mixture of isomers or the single isomers 1,2,3-, 1,2,4- and 1,3,5-trimethylbenzene — the list applies the same NDS value to them

Key parameters

Standard

Standard number

PN-Z-04016-4:1998 (wersja polska)

Title (PL)

Ochrona czystości powietrza — Badania zawartości benzenu i jego homologów z nasyconym łańcuchem bocznym — Oznaczanie trimetylobenzenu na stanowiskach pracy metodą chromatografii gazowej

Title (EN)

Air purity protection — Tests for content of benzene and its homologues with a saturated side chain — Determination of trimethylbenzene 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-04016-4:1998.

2. Air sampling

   Trimethylbenzene vapour is adsorbed on activated charcoal. Volume and flow rate NOT GIVEN.

3. Extraction

   Trimethylbenzene is extracted 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 of the mixture or of a single isomer is compared with NDS 100 mg/m³ and NDSCh 170 mg/m³. It is worth recording in the report whether the result concerns the mixture or an isomer.

Required equipment and apparatus

Reagents, media and consumables

Health and safety (OHS)

• Carbon disulphide is extremely flammable and harmful — it is handled in a fume cupboard, away from ignition sources; the safety data sheet applies
• Trimethylbenzene carries the "skin" notation in the NDS list — a measurement in air does not cover absorption through the skin

Frequently asked questions