Solid Phase Micro Extraction (SPME) is an extraction process for both volatile and semi volatile compounds in preparation for GC or HPLC analysis. One of the major benefits of SPME is that by choosing the proper extracting phase coated on a SPME fiber, target analytes can be extracted leaving unwanted compounds behind in the matrix. This makes SPME very popular in applications where the resulting chromatograms are complex, with many different types of compounds (See SPME application notes at the bottom of the page). Maybe the analyst wants to see polar compounds that are typically related to a foods taste or smell. A polar extraction phase can be chosen to target these compounds, resulting is a simpler, easier chromatogram. Since the extraction uses no solvent, part per trillion (ppt) detection levels are possible and the analyst does not come in contact with potentially dangerous solvents during the analysis.
SPME is performed with a SPME fiber. The fiber is coated with a liquid phase polymer and/or a solid sorbent and is mounted within a needle. There are many different phases available and choosing the correct fiber that is optimal for your analysis is part of the method development process. Some systems, such as the Flex Autosampler, have automated fiber exchange systems (MFX) where multiple fibers can be run in a single sequence. The fiber can be extended out of the needle during extraction or desorption, but retracted inside the needle when the needle needs to pass through septa.
The steps involved in SPME are different depending upon whether you are targeting volatile or semi volatile compounds. For volatiles, the sample is typically placed in a 20ml headspace vial and the sample is heated until the analytes come to equilibrium (For more information about headspace, visit our What is Headspace? page). The SPME needle punctures the vial septa and the fiber is extended into the headspace of the vial. Typically the vial is slowly mixed during this extraction step. Extraction times vary depending upon the analyte, fiber phase etc. and must be optimized as part of the method development. Due to the affinity of the selected fiber for the target analytes, these are absorbed onto the fiber. Once extraction is complete, the fiber is pulled back into the needle; the needle is placed into the injection port. The heat from the injection port and the carrier gas from the GC sweep the compounds off the fiber and into the GC column. The fiber can stay in the injection port, or be moved to a SPME fiber conditioning station to clean it before going onto the next sample.
For semi volatile samples the fiber is exposed directly in the liquid of the sample during extraction. For GC analysis, the fiber can be placed in the injection port and compounds will be swept into the GC. For HPLC analysis, the fiber can be placed into a vial containing a small amount of solvent, extracting the compounds off the fiber.
If you are new to SPME, please reach out to us for recommendations on method parameters and we will be glad to help!
Trained analysts can often detect the flavors in liquors by smelling and tasting a sample. However, in order to establish the quality and essence of a liquor sample, further testing is required. Gas Chromatography coupled with Mass Spectrometry (GC/MS) is an effective tool for the determination of the flavor compounds in an alcohol. Utilizing different sampling techniques, the respective efficiency in the determination of flavor compounds in whiskey samples will be investigated using headspace and SPME.
This application note will compare dynamic headspace and Solid Phase Micro Extraction (SPME) sampling techniques for the detection of the volatile components in plain yogurt.
The ability to automate changing the SPME fibers in a sampling system is invaluable when the analytes of interest are diverse and require varied coatings for the sample extraction. The advantages of automated SPME fiber exchange will be examined in the application.
Tea flavors can vary from spicy to flowery to fruity and any combination thereof. Moreover, the flavor profile of tea can depend on where the tea leaves are grown, the brewing time and temperature, the processing of the tea leaves, and the type of leaf used. Using Head Space Solid Phase Micro Extraction (HS-SPME) sampling in conjunction with Gas Chromatography/Mass Spectrometry (GC/MS) for separation and analysis, assorted teas will be examined for their varied flavor components.
If a tea is steeped for too long or at too high of a temperature, it can become bitter. However, longer steeping times enhance the health benefits of tea by increasing the amount of flavonoids extracted from the tea. This application will look at the effects of time and temperature on the extraction of tea flavors and flavonoids using SPME.
Trichloroanisole (TCA) has an extremely low odor threshold. This compound is primarily responsible for “cork taint” in wines. TCA levels can often be detected by analytical instrumentation but not by consumers and many wines that contain TCA have won awards. TCA does not pose a health risk for anyone who detects a musty odor in their wine. However, the odor of TCA can be off putting and for that reason, wineries prefer to limit consumer exposure to this compound.
There are hundreds of compounds that can contribute to the overall aroma of wine. In order to determine the aroma compounds, analysts can use static headspace, dynamic headspace, Solid Phase Micro Extraction (SPME), liquid-liquid extraction, etc… This analysis will compare three different SPME fibers and their efficiency in discerning aroma compounds.
Every wine has a distinct aroma profile. The major components in the aroma profiles can be very similar; however it is the subtleties that can make all the difference. The seemingly small components in the aroma profile of a wine can often have a large impact on the overall flavor. There are an enormous variety of wine brands, flavors, etc…This application note will focus on three types of white wine and their respective aroma profiles using Headspace Solid Phase Micro Extraction sampling.
Learn MoreThere are two types of SPME sampling techniques. The first entails bringing a sample to equilibrium and exposing the SPME fiber to the headspace of the sample. The second involves placing the SPME fiber directly into the liquid phase of the sample and allowing the analytes to adhere to the fiber directly from the sample. This application note will examine both SPME sampling techniques using Whiskey samples.
Through use of different stationary phases, the SPME fiber can extract analytes of different polarities and volatilities by simply employing a stationary phase that best suits the needs of the application. Coupling SPME sampling with GC for separation and Mass Spectrometry (MS) for analysis provides an ideal method to discern flavor compounds. This paper will employ SPME in order to investigate the flavor composition of different beers providing an examination of what flavors beers have in common and what sets them apart.