Polynuclear Aromatic Hydrocarbons in Water by Automated Solid Phase Extraction

Polynuclear aromatic hydrocarbons (PAHs) consist of fused aromatic rings and are produced as byproducts of fuel burning. As pollutants, they are of concern because some compounds have been identified as carcinogenic, mutagenic, and teratogenic. PAHs are lipophilic and therefore found in the environment primarily in soil, sediment, and oily substances. However, they also appear in surface and ground water indicating a source of pollution.

Instrumentation and Consumables

• FMS, Inc. TurboTrace SPE system (solid phase extraction)

• FMS, Inc. SuperVap Concentrator

• FMS, Inc. 1 g PAH C18 cartridge

• Waters Alliance 2695 HPLC, UV254

Method Summary

TurboTrace SPE

1. Condition cartridge with 15 mL dichloromethane

2. Condition cartridge with 15 mL methanol

3. Condition cartridge with 35 mL water

4. Load 1 L of water sample

5. Dry cartridge for 20 min

6. Rinse sample bottle with 35 mL dichloromethane

7. Elute sample from cartridge with bottle rinse

8. Elute sample with additional 25 mL dichloromethane

SuperVap Concentrator

1. Pre-heat temp: 60 °C

2. Pre-heat time: 20 min

3. Heat in Sensor mode: 60 °C

4. Nitrogen pressure: 9 PSI

Procedure

Three, 1 L samples were acidified to pH 2 with 6 N hydrochloric acid and spiked with 5 μL of Restek 31458 MA EPH aromatic hydrocarbon solution. Sample were then loaded onto the FMS TurboTrace SPE system using vacuum and passed across an FMS PAH C₁₈ cartridge. After sample loading, the cartridges were dried automatically using a stream of nitrogen until no residual water was present, and the cartridges were subsequently eluted using dichloromethane from both the automatic sample bottle rinse and from the elution solvent reservoir. The extracts were concentrated to 1.0 mL and 5 mL acetonitrile was added for solvent exchange. The sample was concentrated to a final volume of 1 mL for HPLC analysis.

Conclusion

The FMS TurboTrace SPE system produces consistent reliable, reproducible results for polynuclear aromatic hydrocarbons in water. The FMS PAH SPE cartridge achieves high recovery extraction in water. Results reported from the TurboTrace™ SPE and SuperVap™ Direct-to-Vial Concentration system (Table I) show high levels of precision and accuracy for the parallel extraction and concentration of PAHs using the FMS integrated Sample-to-Vial systems. With expanded modules, the TurboTraceTM SPE system enables the lab to simultaneously extract eight samples hands free. Compared to manual extraction processes, this automated technique frees up chemists to focus on increasing sample throughput. The addition of direct to GC vial concentration vessels eliminates the need to manually transfer extract from the concentration tubes to the vials and reduces operator error.

Table I: Results for three 1-L samples

FMS Inc.

580 Pleasant Street, Watertown, MA 02472

tel. (617) 393-2396, fax (617) 393-0194

Website: www.fmsenvironmental.com