SPME with Autosamplers

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SPME can be fully automated using a variety of autosampler systems for multiple sample analysis. Once the sample vials are positioned in the autosampler tray, the extraction process begins. With the Combipal system, individual vials are transferred from the sample tray to the heated extraction chamber. This step provides a homogeneous sample and stable temperature for a consistent extraction process. Because SPME extraction is dependent on establishing equilibrium between the sample and fiber surface, constant temperature is necessary. A close-up view of the heat chamber reveals the insertion of the vial into individual spaces and special tin metal caps on the vials used with Combipal. Six vials can be positioned for pre-heating and agitation prior to extraction. The metal caps permit the magnetic capped arm of the autosampler to move and place each vial in a designated location in the sample tray. After a predetermined amount of time, the temperature of the sample is stabilized. The SPME fiber is inserted through the septa seal on the sample vial and the extraction is started. The vial is agitated in the heated chamber by rotation of the vial around the SPME fiber. The metal SPME fibers are shown here, allowing increased flexibility and extended life of the fibers during the rigorous agitation step. After a preset extraction time, the SPME fiber is retracted into the protective needle and injected into the GC injection port. The fiber is exposed and the collected organics desorbed into the GC column for analysis. Metal fibers have demonstrated over 350 extractions with the Combipal autosampler system. Automated SPME provides rapid and reproducible results eliminating the human variable of manual sampling. During the GC analysis, the autosampler removes the sample vial and returns it to the sample starting position before initiating the next extraction.