Rapid Sampling and Identification of Volatile and Semivolatile Organic Compounds by GC-TMS in Support of Decision Quality Data

As analytical chemist(s), the data collected from samples we test represent information. That information may be required to direct environmental clean-up operations, help insure worker safety, or guide decisions for an emergency response to a chemical incident. Therefore, taking the right sample is critical. Not taking the right sample could mean the difference between providing the right information for a time-sensitive response or providing the wrong data that could result in risk to health or increased cost.

The largest single error associated with a sample collection is where, when and how the sample is taken. Collecting the wrong sample, or taking it in the wrong location can lead to inaccurate information. Gathering and analyzing too few samples may provide incomplete information.

On-site analysis is the first step to providing decision quality data when and where it is needed. Most important, is to provide high quality data. Time is also an important factor, where rapid analysis is desirable in order to support increased sample throughput. Gas chromatography–mass spectrometry (GC–MS) provides highly selective identification of target chemicals by pre-programming the system to look for the specific retention time and mass spectrum of a chemical. GC–MS also is able to identify unknown chemicals by searching spectrum of a non-target chemical to reference libraries such as the NIST Mass Spectral Database.

Experimental Conditions

The TRIDION™ -9 Gas Chromatograph – Toroidal Ion Trap Mass Spectrometer (GC-TMS) incorporates High Speed High Resolution GC (HSHR-GC) utilizing a low thermal mass column 5 m × 0.1 mm × 0.4 µm MXT-5 GC column. Using a rapid temperature program 120 °C/min the HSHR-GC chromatographs volatile and semivolatile chemicals within a 3 min runtime. The total cycle time of ~5 min provides sample throughput of 12 samples per hour. This increased sampling capacity results in the ability to generate more information in a shorter time period. More samples equates to more information, which leads to the ability to make the right decision when and where it is required.

Rapid identification is provided in a two-step process. First the on-board target compound identification software identifies all target compounds of interest, and then the unknown identification algorithm extracts and identifies compounds using a subset of the NIST/AMDIS library.

Results

Figure 1 shows the GC-TMS chromatogram and target identification using the standard method for trichloroethylene at 44 ppb and perchloroethylene at 117 ppb for the purpose of rapid site investigation. A CUSTODION™ SPME syringe with a 65 µm polydimethylsiloxane/divinylbenzene (PDMS/DVB) fiber was used to extract analytes from a soil gas sample.

Figure 1: Trichloroethylene at 44 ppb and perchloroethylene at 117 ppb chromatographed in under 40 s.

Conclusions

The TRIDION™-9 hand portable GC-TMS utilizing HSHR-GC for rapid sample analysis covers a wide chemical range with total cycle times of ~5 min. The superior identification algorithms for both target and unknown identification provide a critical new tool for rapid sampling and identification. These advancements in capability result in more samples being analyzed in a shorter period of time so that time critical decisions can be made to mitigate a situation.

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.

796 East Utah Valley Dr., Suite 200, American Fork, UT 84003

Tel. (801) 705-6600

Website: www.torion.com