Rapid On-Site Screening of Environmental VOCs in Soil using Solid Phase Microextractio and a person-Portable GC–MS

Volatile organic compounds (VOCs) in soil were rapidly extracted and concentrated using solid phase microextraction (SPME) followed by on-site analysis and identification with the TRIDION™ -9 portable gas chromatograph – toroidal ion trap mass spectrometer (GC-TMS). 37 VOCs were resolved and analyzed quickly in under 3 min.

The ability to screen soil samples in the field by identifying volatile environmental contaminants is a valuable tool. Results of the screening procedure may be used to guide other sample collection activities and will help identify which EPA extraction methods to use. In combination with the CUSTODION™ SPME syringe, the TRIDION-9 portable GC-TMS can positively identify unknown VOCs in the field and prescreen samples similar to EPA method 3815.

Experimental Conditions

A CUSTODION SPME syringe with a 65 µm polydimethylsiloxane/divinylbenzene (PDMS/DVB) fiber was used to extract analytes from a soil sample spiked with VOCs. Each ranging in concentration from ~15,000 µg/kg to ~2400 µg/kg. 5 g of soil sample were added to 5 mL of H₂O with 25% NaCl (w/v). Sample vial was shaken vigorously by hand for 10 s, after which the SPME fiber was exposed to the headspace for 50 s. This was repeated five times for a total sampling time of ~5 min.

Following sample extraction, the SPME syringe was inserted into the TRIDION-9 GC-TMS injection port where the target analytes were desorbed into a split-splitless injector (280 °C) coupled with a low thermal mass capillary GC column (MXT-5, 5 m × 0.1 mm, 0.4 µm df). After an initial 10 s hold at 40 °C, the GC temperature was increased at 2 °C/s to 280 °C for a total run time of ~2 min. The capillary GC is coupled to a TMS detector. The target analytes were identified with a target compound library and advanced custom deconvolution algorithm.

Results

Figure 1 shows the GC-TMS separation of VOCs spiked into a soil sample. 37 VOCs were detected and positively identified by the TRIDION-9.

Figure 1

Conclusions

The CUSTODION SPME syringe and TRIDION-9 GC-TMS are uniquely suited for field screening of soil samples to support rapid decision making in the field. The short cycle time between injections allows the user to quickly analyze samples on-site with high sensitivity and specificity.

Acknowledgements

Torion®, CUSTODION® and TRIDION™ are trademarks of Torion Technologies Inc. The CUSTODION SPME Syringes are manufactured and sold under license from SUPELCO under US Patent 5,691,206, and/or any divisions, continuations, or revisions thereof.

Torion Technologies Inc.

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tel. (801) 705-6600, email information@torion.com

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