🏭 Volatile organic compounds in emissions
Determination of mass concentration of individual volatile organic compounds (VOC) in waste gases from stationary sources by sorption on activated carbon with solvent or thermal desorption and GC-FID/MS analysis.
Overview
Volatile organic compounds (VOC) emitted from stationary sources (chimneys, emitters) pose a serious environmental problem — they are precursors of tropospheric ozone and photochemical smog, and many of them exhibit carcinogenic effects (benzene, formaldehyde, vinyl chloride). VOC emission control is required by IED Directive 2010/75/EU, Ministry of Environment Regulation on emission standards and integrated permits.
Standard PN-EN 13649 describes the method of sampling gases emitted from stationary sources onto sorbent tubes filled with activated carbon or other sorbents, followed by solvent desorption (carbon disulfide CS₂) or thermal desorption, and chromatographic analysis GC-FID or GC-MS. Version CEN/TS 13649:2014 extended the standard with the option of thermal desorption on TD tubes, eliminating the need to use toxic CS₂.
The method is used by accredited measurement laboratories performing emission measurements commissioned by industrial plants (printing houses, paint shops, chemical, petrochemical, pharmaceutical industries). Results are expressed as mass concentration of individual compounds in mg/m³ at standard conditions, referred to dry gas and conventional O₂ content.
Proper sampling requires isokinetic or proportional sampling from the emitter duct using a heated probe and transport line to prevent condensation.
Method principle
Waste gas is sampled from the emitter duct using a heated probe and passed through sorbent tubes filled with activated carbon (SKC, Anasorb) or polymeric sorbents (Tenax TA, Chromosorb). VOCs adsorb on the sorbent surface. After sampling, fibers are desorbed: (1) by solvent method — washing with CS₂ and analysis of solution on GC-FID, or (2) by thermal method — heating TD tube in thermal desorber (e.g. 300°C) and transport of desorbed analytes with carrier gas (He/N₂) onto GC column with FID or MS detection. Identification based on retention times (FID) or mass spectra (MS), quantification using calibration curves.
Applications
- VOC emission measurements from industrial installations (IPPC integrated permits)
- Compliance control with emission standards (Journal of Laws 2019, item 1705)
- Emission measurements from printing houses, paint shops, chemical plants
- Monitoring of combustion and gas cleaning processes (RTO, adsorption)
- Environmental impact assessments (EIA reports)
- Emissions from petrochemical, refinery, pharmaceutical industries
- Testing effectiveness of cleaning devices (filters, adsorbers)
Key parameters
| Parameter | Value |
|---|---|
| Measurement range | 0.1–10 000 mg/m³ (depending on compound) |
| Detection limit | 0.01–0.1 mg/m³ (TD-GC-MS) |
| Sampling time | 30 min – 4 h (depending on concentration) |
| Sampling flow | 0.1–1.0 L/min (sorbent tubes) |
| Probe temperature | ≥120°C (prevent condensation) |
| Repeatability | ±10–15% (depending on compound and concentration) |
Standard
- Standard number
- PN-EN 13649:2002 (CEN/TS 13649:2014)
- Title (PL)
- Emisje ze źródeł stacjonarnych — Oznaczanie stężenia masowego indywidualnych gazowych związków organicznych — Metoda z sorpcją i desorpcją rozpuszczalnikową lub termiczną
- Title (EN)
- Stationary source emissions — Determination of the mass concentration of individual gaseous organic compounds — Sorptive sampling method followed by solvent extraction or thermal desorption
Step-by-step procedure
1. Field equipment preparation
Check pump and probe tightness. Prepare sorbent tubes (activated carbon or TD). Calibrate rotameter/gas meter.
2. Probe mounting in emitter
Insert heated probe into emitter duct through measurement ports. Connect heated line (≥120°C) to sorbent tubes.
3. Gas parameter measurement
Measure temperature, pressure, gas velocity in duct, humidity. Determine standard conditions (273 K, 101.3 kPa, dry gas).
4. Sample collection on sorbent tubes
Start pump — flow 0.1–1.0 L/min. Sample for 30 min – 4 h. Use 2 tubes in series (main + control).
5. Sample securing
Cap tubes with PTFE plugs. Place in sealed containers, transport coolers. Transport to laboratory within <24 h.
6. Solvent desorption (CS₂)
In laboratory break tube, transfer sorbent to vial. Add 1–2 mL CS₂. Shake 30 min. Centrifuge.
7. Alternative: thermal desorption (TD)
Place TD tube in thermal desorber. Program: 300°C/10 min, focus trap -10°C → 300°C, transfer to GC.
8. GC-FID or GC-MS analysis
Inject 1 µL (CS₂) or transfer from TD. Temperature program: 40°C/3 min → 10°C/min → 250°C. Identification and quantification.
9. Calibration and calculations
Determine concentrations from calibration curves. Convert to standard conditions (273 K, 101.3 kPa, dry gas, conventional O₂).
10. Quality control
Analysis of blank (clean tube), duplicate, control sample with standard. Recovery of control tube <5% of main tube.
Required equipment and apparatus
| Equipment | Example | Indicative price |
|---|---|---|
| Gas chromatograph with FID | Agilent 8890 GC-FID, Shimadzu GC-2030 Nexis | 100 000–250 000 PLN |
| Gas chromatograph with MS | Agilent 7890B/5977B GC-MS, Shimadzu GCMS-QP2020 NX | 250 000–500 000 PLN |
| Thermal desorber | Markes TD100-xr, PerkinElmer TurboMatrix | 80 000–200 000 PLN |
| Sampling pump with rotameter | Gilian GilAir-5, SKC AirChek Touch | 3 000–8 000 PLN |
| Heated emission probe | Titanium isokinetic probe, Paul Gothe, TCR Tecora | 15 000–40 000 PLN |
| Sorbent tubes with activated carbon | SKC 226-01, Anasorb CSC 150/75 mg | 15–30 PLN/pc. |
| TD tubes with Tenax TA | Markes C1-AXXX-5003, ∅6.4 mm × 89 mm | 80–150 PLN/pc. |
Reagents, media and consumables
| Reagent | CAS | Details |
|---|---|---|
| Carbon disulfide (CS₂) pure | 75-15-0 | Solvent for desorption from activated carbon, ultrapure ≥99.9%, 1 L |
| Activated carbon (sorbent) | 7440-44-0 | Granulated, 20/40 mesh, thermally activated, for sorbent tubes |
| Tenax TA (polymeric sorbent) | 24938-68-9 | 2,6-diphenyl-p-phenylene oxide, 60/80 mesh, for thermal desorption |
| VOC standards in CS₂ or methanol | — | Certified mixtures: BTEX, alcohols, esters, ketones, chlorinated — for GC calibration |
| Calibration gases (BTEX in N₂) | — | Cylinders with standard gas mixtures 1–100 ppm, accredited certificate |
| Helium or nitrogen UHP 5.0 | 7440-59-7 | GC carrier gas, purity ≥99.999%, 50 L cylinder |
Health and safety (OHS)
- CS₂ — extremely flammable (Tfl = -30°C), toxic, neurotoxic! Work only in fume hood with ventilation
- Waste gases may contain toxic compounds (benzene, chlorinated) — mask with ABE canister during sampling
- Work at height (chimney platforms) — harnesses, training, first aid kit
- Gas cylinders — protection against tipping, checked reducers, leak detector
- GC-FID — flammable gases (H₂, air) — hydrogen detector in laboratory, forced ventilation