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Analysis of Polynuclear Aromatic Hydrocarbons Using US EPA Quick Turnaround Method (QTM) by CDS Empore™ Disk

  • Mar 18
  • 3 min read

A simple, validated method for extracting 16 PAHs from 100 mL water samples using the CDS Empore™ C18 47mm disk, with GC-FID quantification achieving average RSDs below 6.2%.

Authors: Guotao Lu


Why PAH Monitoring Matters


Polycyclic aromatic hydrocarbons (PAHs) are among the most hazardous organic pollutants found in the environment. This group of over 100 compounds — formed during the incomplete combustion of fuels like wood, coal, diesel, and oil — is also present in crude oil, plastics, lubricants, and many industrial products.


Seven PAH compounds have been classified by the US EPA as potentially carcinogenic, mutagenic, and teratogenic: benz[a]anthracene, benzo[a]pyrene, benzo[b]fluoranthene, benzo[k]fluoranthene, chrysene, dibenz[a,h]anthracene, and indeno[1,2,3-cd]pyrene. Reliable monitoring in environmental water samples — especially drinking water — is critical for public safety.


Challenge: Traditional liquid-liquid extraction methods for PAHs are time-consuming and require large solvent volumes. The EPA Quick Turnaround Method (QTM) using SPE disk technology offers a faster, cleaner alternative.

Extraction Method


The method uses a 47mm CDS Empore™ C18 disk with an all-glass filtration assembly. The complete protocol follows EPA QTM guidelines for PAH extraction from groundwater samples.


Disk Preparation


  1. Wash — Add 5 mL methylene chloride to the reservoir, pull a small amount through the disk, soak for 1 minute, then pull through and allow to dry.

  2. Condition — Add 5 mL methanol, pull a small amount through, soak for 1 minute, then pull through leaving 3–5 mm on the surface.

  3. Equilibrate — Add 10 mL reagent water, pull most through, leaving 3–5 mm on the surface.


Sample Extraction


  1. Add 0.5 mL methanol to the 100 mL water sample and mix well.

  2. Transfer to the reservoir and filter under vacuum.

  3. Rinse the sample bottle with 10 mL methylene chloride, wet the disk surface with ~0.5 mL acetone, then transfer the rinse through the disk. Soak for 1 minute, then pull through.

  4. Repeat the rinse with 5 mL methylene chloride; add 5 mL directly onto the disk, soak 1 minute, pull through.

  5. Dry the combined eluate with anhydrous sodium sulfate, rinse with two 5 mL aliquots of methylene chloride.

  6. Concentrate to 1.0 mL under gentle nitrogen stream (~30°C).

  7. Analyze by GC-FID.

Tip: If interfering compounds are present in your samples, additional clean-up protocols described in the EPA QTM method should be applied before GC-FID analysis.

Results & Advantages


The CDS Empore™ C18 47mm disk successfully extracted 16 PAH compounds from groundwater samples at two concentration levels (20 ppb and 200 ppb). Detailed recovery and reproducibility data are shown below.


  • At 20 ppb — Recovery rates of 48.2–94.0% with average RSD of 5.9%, demonstrating excellent reproducibility at low concentrations (n=3)

  • At 200 ppb — Recovery rates of 47.0–74.4% with average RSD of 6.2%, confirming consistent performance across a wide concentration range (n=6)

  • Consistently higher recoveries observed for heavier PAH compounds

  • All RSDs below 10% except surrogate compound bromofluorene (14.4%)


Compared to traditional SPE cartridges with loosely packed media, the Empore™ disk membrane offers several advantages for large-volume water sample analysis:

  • Higher extraction efficiency — Uniformly packed sorbent particles eliminate channeling effects

  • Faster flow rates — Thin membrane design enables rapid processing of 100 mL samples

  • Lower solvent consumption — Minimal elution volume reduces waste and evaporation time

  • Screening capability — Method is suitable as a rapid screening tool for environmental testing labs


Conclusion


This application note demonstrates that the CDS Empore™ C18 47mm disk provides a simple, effective extraction solution for PAH analysis in water samples following EPA QTM methodology. With RSDs below 6.2% and the ability to process 100 mL samples efficiently, this method is ideal for environmental testing laboratories seeking reliable, high-throughput PAH screening.




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