🌿 PAHs in Soil (GC-MS)
In short
Quantitative determination of the 16 polycyclic aromatic hydrocarbons (PAH) of the US EPA priority list in soil: extraction with acetone and petroleum ether from a field-moist or chemically dried sample, clean-up on silica gel if necessary, and GC-MS determination with deuterated PAHs as internal standards. The test is performed according to PN-ISO 18287:2008 (Polish version; adopts ISO 18287:2006 [IDT]); Compounds determined: 16 PAHs of the US EPA priority list (1982). The procedure comprises 6 steps; it is used for: Assessment of contamination of the surface of the earth — comparison with the permissible PAH contents for groups of land (Journal of Laws 2016, item 1395), Soils of all types, field-moist or chemically dried — a wide range of PAH contamination, Post-industrial areas, transport areas and other land of group IV — permissible benzo(a)pyrene content 20 mg/kg dry matter.
At a glance
- Standard: PN-ISO 18287:2008 (Polish version; adopts ISO 18287:2006 [IDT])
- Category: Environmental
- Procedure steps: 6
- Compounds determined: 16 PAHs of the US EPA priority list (1982)
- Lower limit of application: 0.01 mg/kg dry matter for each compound
- Extractant: acetone + petroleum ether (40–60 °C): at least 50 ml + 50 ml; for a wet sample at least 100 ml of acetone
Overview
STATUS (as of 28.10.2026). PN-ISO 18287:2008 — Polish version, published 22.08.2008, implements ISO 18287:2006 [IDT]. The standard is current — no withdrawal note.
SCOPE (clause 1). The standard specifies the quantitative determination of the 16 PAHs of the US EPA priority list (1982) in soil. It applies to all types of soil — field-moist or chemically dried samples — and to a wide range of PAH contamination levels. Under the conditions of the standard a lower limit of application of 0.01 mg/kg dry matter can be ensured for each compound. Related standards: sampling (ISO 10381-1, ISO 10381-8 for stockpiles), dry matter (ISO 11465), pretreatment of samples for the determination of organic contaminants (ISO 14507) or freeze-drying (ISO 16720).
PRINCIPLE (clause 3). The extractant is acetone with petroleum ether. Acetone is an efficient extractant because it breaks down soil aggregates; petroleum ether increases the efficiency of extraction and is needed as the solvent in the subsequent concentration. An extraction method should use at least 50 ml of acetone and 50 ml of petroleum ether for a chemically dried sample, and for a wet sample at least 100 ml of acetone. Other ways of extraction can give the same results if these recommendations are observed. When the sample contains a large amount of water, or water has been added, sodium chloride is added to improve extraction. The standard describes two methods: A (two-step) — the field-moist sample is extracted twice with acetone, petroleum ether is added to the extract, which is washed twice with water, and the organic layer is dried with anhydrous sodium sulfate; B (one-step) — the field-moist sample is extracted with a mixture of acetone, petroleum ether, water and sodium chloride in fixed proportions, and an aliquot of the organic layer is dried with sodium sulfate. If necessary, clean-up by adsorption chromatography on silica gel and a concentration step are added. The extract is analysed by capillary gas chromatography with mass spectrometric detection, with deuterated PAHs as internal standards.
REAGENTS (clause 4). All of recognized analytical grade and free from PAH — confirmed by a blank determination. Distilled water; acetone, petroleum ether (boiling range 40–60 °C), cyclohexane and isooctane for residue analysis; anhydrous sodium chloride and sodium sulfate; silica gel 60 (particles 63–200 µm) — heated for at least 3 h at 450 °C, dried for at least 5 h at 130 °C before use and deactivated with 10 % water (by mass), stored without access of air and used within a week. Calibration solutions are prepared in cyclohexane, preferably from certified standard solutions.
INTERNAL STANDARDS (4.11, Table 1). Deuterated PAHs with properties similar to the compounds determined: naphthalene-d8, acenaphthene-d10, phenanthrene-d8, benz[a]anthracene-d12, benzo[e]pyrene-d12 and perylene-d12; their stability is verified regularly.
SOIL — LEGAL REQUIREMENT. Regulation of the Minister of the Environment of 1 September 2016 on the method of assessing contamination of the surface of the earth (Journal of Laws 2016, item 1395), Annex 1: permissible contents in soil (layer 0–0.25 m, mg/kg dry matter of the earth fraction < 2 mm) are given for 10 PAHs individually, by groups of land. For benzo(a)pyrene: group I (including residential areas) 0.1, group II 0.1, group III (including forests) 1, group IV (including industrial areas, mining land, transport areas) 20 mg/kg.
WHAT WE DO NOT GIVE HERE. The apparatus, the test portion mass and solvent volumes in methods A and B, the course of the clean-up, chromatographic conditions, calibration, calculation and precision data (clause 5 onwards) — we only know the principle and the reagents. We do not state durations and temperatures of steps that the available part of the standard does not give.
Method principle
Field-moist (or chemically dried) soil is extracted with acetone and petroleum ether: in method A twice with acetone, then with the addition of petroleum ether and two washings with water; in method B once with a mixture of acetone, petroleum ether, water and sodium chloride. The organic layer is dried with anhydrous sodium sulfate, cleaned up on deactivated silica gel if necessary, and concentrated.
The PAHs are separated by capillary gas chromatography and identified and quantified by mass spectrometry, with deuterated PAHs as internal standards. The result is expressed on a dry matter basis (dry matter according to ISO 11465).
Applications
- Assessment of contamination of the surface of the earth — comparison with the permissible PAH contents for groups of land (Journal of Laws 2016, item 1395)
- Soils of all types, field-moist or chemically dried — a wide range of PAH contamination
- Post-industrial areas, transport areas and other land of group IV — permissible benzo(a)pyrene content 20 mg/kg dry matter
- Residential and recreational areas (group I) — permissible benzo(a)pyrene content 0.1 mg/kg dry matter
Key parameters
| Parameter | Value |
|---|---|
| Compounds determined | 16 PAHs of the US EPA priority list (1982) |
| Lower limit of application | 0.01 mg/kg dry matter for each compound |
| Extractant | acetone + petroleum ether (40–60 °C): at least 50 ml + 50 ml; for a wet sample at least 100 ml of acetone |
| Extraction methods | A — two-step; B — one-step with water and sodium chloride |
| Clean-up (if necessary) | silica gel 60 deactivated with 10 % water |
| Detection | GC-MS, internal standards: naphthalene-d8, acenaphthene-d10, phenanthrene-d8, benz[a]anthracene-d12, benzo[e]pyrene-d12, perylene-d12 |
| Benzo(a)pyrene — permissible contents | groups I and II: 0.1; group III: 1; group IV: 20 mg/kg dry matter (Journal of Laws 2016, item 1395) |
Standard
- Standard number
- PN-ISO 18287:2008 (Polish version; adopts ISO 18287:2006 [IDT])
- Title (PL)
- Jakość gleby — Oznaczanie zawartości wielopierścieniowych węglowodorów aromatycznych (PAH) — Metoda chromatografii gazowej z detekcją za pomocą spektrometrii mas (GC-MS)
- Title (EN)
- Soil quality — Determination of polycyclic aromatic hydrocarbons (PAH) — Gas chromatographic method with mass spectrometric detection (GC-MS)
Step-by-step procedure
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Sampling and sample preparation
Sampling according to ISO 10381-1 (stockpiles — ISO 10381-8); pretreatment for the determination of organic contaminants according to ISO 14507 or freeze-drying according to ISO 16720. A field-moist or chemically dried sample is tested; dry matter is determined according to ISO 11465 (clauses 1–2).
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Adding internal standards
Deuterated PAHs from Table 1 as internal standards for the GC-MS determination (4.11, clause 3).
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Extraction
Method A: extraction twice with acetone, addition of petroleum ether, washing twice with water, drying the organic layer with sodium sulfate. Method B: extraction with a mixture of acetone, petroleum ether, water and sodium chloride in fixed proportions, drying an aliquot of the organic layer. At least 50 ml of acetone and 50 ml of petroleum ether; for a wet sample at least 100 ml of acetone (clause 3).
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Clean-up and concentration — if necessary
Adsorption chromatography on silica gel 60 deactivated with 10 % water and concentration of the extract (clause 3, 4.10).
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GC-MS determination
Capillary gas chromatography with mass spectrometric detection; calibration with PAH solutions in cyclohexane, quantification relative to the deuterated internal standards (clause 3, 4.12).
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Blank and result
A blank determination confirms that the reagents do not contain PAHs in detectable concentrations (clause 4). The result for each PAH in mg/kg dry matter.
Required equipment and apparatus
| Equipment | Example | Indicative price |
|---|---|---|
| Gas chromatograph with mass spectrometer | capillary column; identification and quantification with deuterated internal standards (clause 3) | — |
| Glassware for extraction, phase separation and concentration | volumetric flasks for standard solutions; details of the apparatus — clause 5 of the standard | — |
| Shaking machine | among others for deactivating silica gel (2 h after adding water) (4.10) | — |
| Furnace and drying oven | heating silica gel for at least 3 h at 450 °C and drying it for at least 5 h at 130 °C (4.10) | — |
| Desiccator | with magnesium perchlorate or another drying agent — for storing silica gel (4.8, 4.10) | — |
Reagents, media and consumables
| Reagent | CAS | Details |
|---|---|---|
| Acetone for residue analysis | 67-64-1 | extractant — breaks down soil aggregates (4.2, clause 3) |
| Petroleum ether, boiling range 40–60 °C | — | extractant and solvent for concentration (4.3, clause 3) |
| Cyclohexane and isooctane for residue analysis | — | cyclohexane — for diluting calibration solutions (4.4–4.5, 4.12) |
| Sodium chloride and sodium sulfate, anhydrous | — | sodium chloride improves extraction of samples with a large amount of water; sodium sulfate dries the organic layer (4.6–4.7) |
| Silica gel 60 (63–200 µm) | — | heated ≥ 3 h at 450 °C, stored over a drying agent, before use ≥ 5 h at 130 °C and 10 % water; use within a week (4.9–4.10) |
| PAH standards and deuterated PAHs | — | the 16 PAHs and the internal standards of Table 1, preferably certified; verify the stability of internal standards regularly (4.11–4.12) |
Health and safety (OHS)
- Acetone, petroleum ether, cyclohexane and isooctane are flammable — work away from ignition sources, in a fume hood
- PAH standards — some of the compounds are considered carcinogenic; follow the safety data sheets of the standards
- Magnesium perchlorate (drying agent in the desiccator) is a strong oxidizer — do not combine it with organic substances
Frequently asked questions
Which standard describes this test?
The test is performed according to PN-ISO 18287:2008 (Polish version; adopts ISO 18287:2006 [IDT]) — “Soil quality — Determination of polycyclic aromatic hydrocarbons (PAH) — Gas chromatographic method with mass spectrometric detection (GC-MS)”.
How does this method work?
Field-moist (or chemically dried) soil is extracted with acetone and petroleum ether: in method A twice with acetone, then with the addition of petroleum ether and two washings with water; in method B once with a mixture of acetone, petroleum ether, water and sodium chloride. The organic layer is dried with anhydrous sodium sulfate, cleaned up on deactivated silica gel if necessary, and concentrated.
What is the measuring range and accuracy?
Compounds determined: 16 PAHs of the US EPA priority list (1982); Lower limit of application: 0.01 mg/kg dry matter for each compound; Extractant: acetone + petroleum ether (40–60 °C): at least 50 ml + 50 ml; for a wet sample at least 100 ml of acetone; Extraction methods: A — two-step; B — one-step with water and sodium chloride.
How long does the test take?
The procedure comprises 6 steps. The standard does not give a duration for every stage — the laboratory's own procedure decides.
What equipment is required?
Gas chromatograph with mass spectrometer, Glassware for extraction, phase separation and concentration, Shaking machine, Furnace and drying oven, Desiccator.
Where is this test used?
Assessment of contamination of the surface of the earth — comparison with the permissible PAH contents for groups of land (Journal of Laws 2016, item 1395); Soils of all types, field-moist or chemically dried — a wide range of PAH contamination; Post-industrial areas, transport areas and other land of group IV — permissible benzo(a)pyrene content 20 mg/kg dry matter; Residential and recreational areas (group I) — permissible benzo(a)pyrene content 0.1 mg/kg dry matter.
What safety precautions apply?
Acetone, petroleum ether, cyclohexane and isooctane are flammable — work away from ignition sources, in a fume hood; PAH standards — some of the compounds are considered carcinogenic; follow the safety data sheets of the standards; Magnesium perchlorate (drying agent in the desiccator) is a strong oxidizer — do not combine it with organic substances.
Which laboratory can perform this test?
The test is performed by laboratories accredited to ISO/IEC 17025. On LabCoda you can find them by the standard number PN-ISO 18287.