ACQUISITION OF GAS CHROMATOGRAPH/MASS SPECTROMETER WITH FRONT-END GERSTEL LINE FOR AUTOMATED SAMPLE PREPARATION/INTRODUCTION AND INCREASED SENSITIVITY

<b>Project Methods</b><br> The analytical separation of organic compounds originating from a wide range of natural or synthetic sources by gas chromatography (GC) as well as their subsequent identification via coupled mass spectrometry (MS) are well established technologies. The front-end additions to GC available from Gerstel Inc. offer unique improvements in sample preparation/introduction that result in unprecedented increases in sensitivity in the analysis. This proposal now allows us toacquire a coupled gas chromatograph (Agilent Technologies 7890B series) / mass spectrometer (Agilent Technologies 5977B Inert Plus MSD Turbo EI) with a mounted front-end Gerstel product line. Three Gerstel modules form the core of the front-end additions: 1) the Multipurpose Sampler, an autosampler and sample preparation robot, 2) the Thermal Desorption Unit (TDU), that allows introduction of a wide range of different samples (liquids, solids, adsorbent-filled tubes, Gerstel Twister®, Gerstel Thin Film Solid Phase Microextraction) and subsequent thermal desorption, and is connected to 3) the Cooled Injection System CIS 4C, a high-performance cryo-trap that after thermal desorption of injected samples refocuses the analytes before transferring the entire sample by temperature vaporization to the GC which results in excellent recovery and separation of peaks, and extremely low detection limits. In addition to its extremely high sensitivity the design of the front-end Gerstel line offers a diverse and unique set of options for sample collection and preparation: 1) liquid samples can be loaded by syringe or from Micro-Vials via thermal extraction; 2) the Automated Dynamic Headspace Module can be used to extract and concentrate VOCs from liquid or solid samples by trapping the headspace above the sample on adsorbent-filled tubes that are subsequently inserted into the TDU; 3) the Automated Solid Phase Micro Extraction (SPME) module offers a standard technique for high throughput extraction and concentration of VOCs; 4) the Twister® Stir Bar Sorptive Extraction (SBSE) and the Thin Film-Solid Phase Micro Extraction (TF-SPME) technologies provide 1000-fold lower detection limits due to the increased surface area and adsorbent phase volume. Both devices can be used in headspace mode for VOC collections from the gas phase, or in immersion mode for compound collection from aqueous samples. The devices are then inserted into the TDU where bound compounds are released by heating for analysis by GC/MS. The subsequent cryo-trapping of released compounds enables analysis of entire samples thus further adding to the sensitivity of detection. A unique feature of Twister® Stir Bar and TF-SPME is the ability to perform VOC collections under field/environmental conditions thus overcoming the need to first sample material (i.e. plants, insects, water) for a later lab-based analysis. Besides the described front-end additions Gerstel also offers an Olfactory Detection Port (ODP) downstream of the GC that allows to split compounds that have been separated in a defined ratio for the subsequent parallel MS and human olfactory analysis.The Gerstel GC/MS system will facilitate the collection and identification of organic compounds from a wide variety of organisms and samples with extremely low detection limits, under different conditions (i.e. climate scenarios) and from different matrices (i.e. gaseous vs aqueous) and environments (i.e. lab vs field, air vs soil).