🌿 TPH in soil (C10–C40)
In short
Determination of total petroleum hydrocarbons (TPH) in the C10–C40 range in soil by gas chromatography with FID detection. The test is performed according to PN-EN ISO 16703:2011; Analyte range: Hydrocarbons C10–C40. The procedure comprises 7 steps (about 3 h 45 min–7 h 45 min in total); it is used for: Assessment of soil contamination with petroleum substances, Testing gas station and fuel depot sites, Monitoring leaks from underground storage tanks.
At a glance
- Standard: PN-EN ISO 16703:2011
- Category: Environmental
- Procedure steps: 7
- Total time of stages: 3 h 45 min–7 h 45 min
- Analyte range: Hydrocarbons C10–C40
- Detection limit: 10 mg/kg d.m.
- Measurement range: 10–50,000 mg/kg
Overview
Total petroleum hydrocarbons (TPH) in the C10–C40 range include petroleum fractions from naphtha to heavy oils and greases. It is a key indicator of soil contamination with petroleum substances, resulting from fuel tank leaks, pipeline failures, gas station operations, and petrochemical plant activities.
ISO 16703 defines the procedure for solvent extraction (acetone/hexane), florisil cleanup (removal of polar compounds), and GC-FID analysis. The result includes the sum of C10–C40 hydrocarbons, with optional division into fractions (C10–C12, C12–C16, C16–C21, C21–C35, C35–C40). Permissible TPH concentration in soil: 50 mg/kg (Group I) to 3000 mg/kg (Group IV) according to Polish regulation.
Method principle
The soil sample is extracted with acetone and hexane. The extract is cleaned on a florisil column to remove polar compounds (natural fats, humic substances) and analyzed by gas chromatograph with FID detector. The sum of peak areas between retention times of n-decane (C10) and n-tetracontane (C40) is converted to TPH concentration using a calibration curve prepared from a mixture of mineral oil and motor oil.
Applications
- Assessment of soil contamination with petroleum substances
- Testing gas station and fuel depot sites
- Monitoring leaks from underground storage tanks
- Control of soil remediation from petroleum contamination
- Soil testing for construction projects
- Assessment of industrial waste for hydrocarbon content
Key parameters
| Parameter | Value |
|---|---|
| Analyte range | Hydrocarbons C10–C40 |
| Detection limit | 10 mg/kg d.m. |
| Measurement range | 10–50,000 mg/kg |
| Limit (Group I) | 50 mg/kg d.m. |
| Precision (CV) | 10–25% |
Standard
- Standard number
- PN-EN ISO 16703:2011
- Title (PL)
- Jakość gleby — Oznaczanie zawartości węglowodorów w zakresie od C10 do C40 metodą chromatografii gazowej
- Title (EN)
- Soil quality — Determination of content of hydrocarbon in the range C10 to C40 by gas chromatography
Step-by-step procedure
-
Sample preparation
Homogenize soil sample. Weigh 10 g into conical flask. Add 10 mL acetone and 20 mL hexane.
-
Extraction
Shake on orbital shaker at 200 rpm for 2 h or extract in Soxhlet for 6 h.
-
Phase separation
Add anhydrous Na₂SO₄ (5 g) to remove water. Transfer hexane phase to volumetric flask.
-
Florisil cleanup
Pass extract through column with 2 g florisil. Elute with 15 mL hexane. Collect eluate.
-
Concentration
Evaporate to 1 mL under nitrogen stream.
-
GC-FID analysis
Program: 40°C (2 min) → 10°C/min → 350°C (10 min). Injection 1 µL splitless.
-
Calculations
Sum peak areas in C10–C40 window. Subtract blank. Convert to mg/kg dry mass.
Required equipment and apparatus
| Equipment | Example | Indicative price |
|---|---|---|
| Gas chromatograph GC-FID | Agilent 8890, Shimadzu GC-2030, Thermo TRACE 1310 | 150,000–300,000 PLN |
| Capillary column | DB-1 or HP-1, 15 m × 0.25 mm × 0.1 µm | 1,500–3,000 PLN |
| Extraction system (shaker/Soxhlet) | IKA KS 4000i control, BÜCHI E-816 | 10,000–50,000 PLN |
| SPE florisil columns | Supelco LC-Florisil 1 g/6 mL | 15–30 PLN/pc. |
| Rotary evaporator | Büchi R-300 | 15,000–35,000 PLN |
Reagents, media and consumables
| Reagent | CAS | Details |
|---|---|---|
| n-Hexane for pesticide analysis | 110-54-3 | Extraction and elution solvent |
| Acetone for pesticide analysis | 67-64-1 | Extraction solvent |
| Activated florisil | 1343-88-0 | For extraction cleanup, 60–100 mesh |
| TPH standard (mineral oil) | — | Mixture of mineral and motor oil, certified CRM |
| n-Decane (C10) and n-tetracontane (C40) | — | Standards to determine retention window |
Health and safety (OHS)
- n-Hexane — flammable, neurotoxic. Work in fume hood, no open flames.
- Acetone — flammable, irritating. Store away from ignition sources.
- Petroleum-contaminated soil samples — nitrile gloves mandatory
- Solvent waste — collect in organic waste containers
Frequently asked questions
Which standard describes this test?
The test is performed according to PN-EN ISO 16703:2011 — “Soil quality — Determination of content of hydrocarbon in the range C10 to C40 by gas chromatography”.
How does this method work?
The soil sample is extracted with acetone and hexane. The extract is cleaned on a florisil column to remove polar compounds (natural fats, humic substances) and analyzed by gas chromatograph with FID detector.
What is the measuring range and accuracy?
Analyte range: Hydrocarbons C10–C40; Detection limit: 10 mg/kg d.m.; Measurement range: 10–50,000 mg/kg; Limit (Group I): 50 mg/kg d.m.
How long does the test take?
The times given for the individual stages add up to approximately 3 h 45 min–7 h 45 min. The procedure comprises 7 steps.
What equipment is required?
Gas chromatograph GC-FID, Capillary column, Extraction system (shaker/Soxhlet), SPE florisil columns, Rotary evaporator. Indicative cost of the core instrument (Gas chromatograph GC-FID): 150,000–300,000 PLN.
Where is this test used?
Assessment of soil contamination with petroleum substances; Testing gas station and fuel depot sites; Monitoring leaks from underground storage tanks; Control of soil remediation from petroleum contamination; Soil testing for construction projects; Assessment of industrial waste for hydrocarbon content.
What safety precautions apply?
n-Hexane — flammable, neurotoxic. Work in fume hood, no open flames.; Acetone — flammable, irritating. Store away from ignition sources.; Petroleum-contaminated soil samples — nitrile gloves mandatory; Solvent waste — collect in organic waste containers.
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-EN ISO 16703.