Automated Extraction of Organochlorine Pesticides with In-Line Florisil Cleanup

Organochlorine pesticides are among the more notorious organic pollutants. Gaining wide spread attention into the latter part of the 20th century, and ultimately leading to their ban, OCPs remain with us as a legacy contaminant in the environment. In water samples, OCPs are monitored by the U.S. Environmental Protection Agency by various methods including methods EPA 508, EPA 608, and EPA 8081.

The use of solid phase extraction (SPE) can rapidly increase both extraction efficiency and reduce lab solvent usage. By implementing the FMS TurboTrace® ABN system with its dual cartridge functionality, an in-line florisil cartridge can be added to perform automated extract clean-up during the elution step.

Instrumentation

• FMS, Inc. TurboTrace® ABN SPE system

• FMS, Inc. SuperVap® 12 Concentrator

• 55 mL SuperVap Tubes vials

• Agilent 7890 GC with μECD detector

Consumables

• FMS Inc. 1 g C18 SPE cartridges

• FMS Inc. Florisil SPE cartridges

• Acetone, pesticide grade or equivalent

• n-hexane, pesticide grade or equivalent

• HPLC grade water

• 6 N HCL

• Anhydrous sodium sulfate, ACS grade or equivalent

SPE Procedure

1. Condition Florisil/Na₂SO₄ SPE cartridge with 20 mL 10% acetone in hexane
2. Condition C18 SPE cartridge with 10 mL acetone
3. Condition C18 SPE cartridges with 20 mL H₂O
4. Load samples across C18 SPE cartridges via vacuum
5. Dry C18 cartridge with N₂ for 10 min
6. Automatic solvent rinse of sample bottle with 10% acetone in hexane
7. Bottle rinse loaded across both cartridges and collected in SuperVap concentrator
8. Additional 10 mL elution solvent passed C18 cartridges
9. 10 mL elution solvent passed across Florisil cartridge and nitrogen purged to SuperVap

Total elution solvent: ~40 mL

SuperVap

1. Preheat temperature: 55 °C
2. Evap mode: 10 psi nitrogen with sensor

Figure 1: Chromatogram of an LFB extraction at .5 μg/L.

Results

Results of IPR study performed on Turbo Trace ABN system with in-line Florisil

Conclusions

Extraction of the water samples performed on the TurboTrace ABN system enabled a fully automated extraction process using its dual cartridge capabilities. Samples were loaded across the C18 cartridges, then eluted through the Florisil cartridges in succession. The addition of Na₂SO₄ to the clean-up cartridge enabled residual water removal from the extract without a separate, manual step. Analytical results yielded spiked recoveries of Organochlorine pesticides to all be between 70–130%, with low RSDs.

FMS, Inc.
580 Pleasant Street, Watertown, MA 02472
tel. (617) 393-2396, fax (617) 393-0194
Website: www.fms-inc.com