Solid-Phase Extraction (SPE)

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Three Common SPE Problems

An excerpt from LCGC’s e-learning tutorial on common solid-phase extraction (SPE) problems at CHROMacademy.com

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A solid phase microextraction (SPME) method was developed using a new overcoated PDMS–DVB fiber for immersion extraction of pesticide residues from spaghetti sauce. The overcoating, which consisted of polydimethylsiloxane, offered protection to the SPME fiber, making it more resistant to physical and chemical damage. Also, it increased fiber selectivity for the smaller analyte molecules over macromolecules present in sample matrix. This then allowed it to be used in immersion extraction of a very complex matrix-spaghetti sauce. Performance of the overcoated fiber was compared to a nonovercoated fiber of the same chemistry for method accuracy, precision, and durability. The SPME method developed using the overcoated fiber was then compared to extraction of the same pesticides in spaghetti sauce using a conventional QuEChERS method for extraction and cleanup. SPME was comparable to the QuEChERs method for both accuracy and precision. However, its main advantage over QuEChERS was in sensitivity and method simplicity.

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Is your swimming pool clean and safe? Recreational water illness, most commonly in the form of digestive tract illness or skin, ear, or respiratory infections, is often caused by water contamination. The authors present a robust method, using solid-phase extraction and high-resolution mass spectrometry, for monitoring swimming pool water.

Researchers at Agriculture and Agri-Food Canada (St-Hyacinthe, Quebec, Canada) and McGill University (Ste-Anne-de-Bellevue, Quebec, Canada) used headspace solid-phase microextraction (SPME) in conjunction with gas chromatography?mass spectrometry (GC?MS) to measure flavor compounds in commercial cheddar cheese and enzyme-modified cheddar cheese.

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Over the last 10 years, several solvent-free microextraction techniques for gas chromatography (GC) and mass spectrometry (MS) have been developed. Two of these techniques, solid-phase microextraction (SPME) and stir-bar sorptive extraction (SBSE), are available commercially for the analysis of volatile compounds, such as flavors in foods and beverages, and toxic organic compounds in environmental applications. Other techniques, such as open tubular trapping, inside needle capillary adsorption trap (1), in-tube SPME, capillary microextraction, needle trap, and headspace solid-phase dynamic extraction (2), were also developed for different applications. The basic principle for all of these techniques is essentially the same. Volatile and semivolatile compounds are adsorbed on a sorbent coating, often packed on the interior surface of a capillary column or stainless steel needle. After the sample is concentrated on the coating, the compounds are desorbed thermally in the heated injection port of a gas..

This article aims to demonstrate the unique capability of resin-based mixed-mode solid-phase extraction (SPE) to achieve efficient extraction of basic drugs from plasma. Optimized pore size of the method minimizes retention of high molecular weight matrix components present in the biological fluid samples. The interferences are removed, ensuring extremely clean extracts for subsequent liquid chromatography?mass spectrometry-mass spectrometry (LC-MS-MS) analysis.