Solid-phase microextraction sorbents

The choice of solid-phase microextraction sorbent phase was shown to be important especially for the amino metabolities of trinitrotoluene and RDX, which were extracted better on polar phases. Although equilibration times were quite lengthy, on the order of 30 min or greater, a sampling time of only 10 min was shown to be sufficient for achieving low part-per-billion (ppb) to part-per-trillion (ppt) detection limits for trinitrotoluene and the amino metabolities in real seawater samples. Solid-phase microextraction was ideal for rapid screening of explosives in seawater samples. 

EXTRACTION CAPABILITY OF SOLID PHASE MICROEXTRACTION SORBENTS... 

Extraction Capability of Solid Phase Microextraction Sorbents... 

SOLID-PHASE MICROEXTRACTION SORBENTS Thomas J. Bruno and Paris D. N. Svoronos... 

Solid Phase Sorbents. Solid Phase Extraction Formats. Automated Solid Phase Extraction. Solid Phase Microextraction. Applications of SPE and SPME. 

Packed sorbent beds may suffer from poor efficiency due to channelling solid phase microextraction difficult to calibrate and replicate, especially with gaseous samples. 

Water extraction is also occasionally combined with solid-phase microextraction. Thus Wennrich et al. [97] determined chlorophenols in soil by using accelerated water extraction to remove the chlorophenols from the soil followed by adsorption onto a solid sorbent for ten minutes at 125 °C. Low ppb detection limits were thus achieved. 

The following table provides a listing of the major types of sorbents used in sampling, concentrating, odor profiling, and air and water pollution research.16 These materials are useful in a wide variety of research and control applications. Many can be obtained commercially in different sizes, depending on the application involved. The purpose of this table is to aid in the choice of a sorbent for a given analysis. Information that is specific for solid phase microextraction (SPME) is provided elsewhere in this chapter. 

Sorbent/ solid phase Solid phase extraction (SPE) Solid phase microextraction (SPME) Stir bar sorptive extraction (SBSE) INCAT/OTT/in-tube-SPME SPDE Headspace-solid phase microextraction (HS-SPME) Headspace stir-bar sorptive extraction (HS-SBSE) Purge-and-sorbent trapping Spray-and-sorbent trapping... 

Stir bar sorptive extraction (SBSE), an approach theoretically similar to SPME, was recently introduced [141] for the trace enrichment of organic compounds from aqueous food, biological, and environmental samples. A stir bar is coated with a sorbent and immersed in the sample to extract the analyte from solution. To date, reported SBSE procedures were not usually operated as exhaustive extraction procedures however, SBSE has a greater capacity for quantitative extraction than SPME. The sample is typically stirred with the coated stir bar for a specified time, usually for less than 60 minutes, depending on the sample volume and the stirring speed, to approach equilibrium. SBSE improves on the low concentration capability of in-sample solid-phase microextraction (IS-SPME). 

Y. Luo and J. Pawliszyn, Solid phase microextraction (SPME) and membrane extraction with a sorbent interface (MESI) in organic analysis, in A. J. Handley, ed., Extraction Methods in Organic Analysis, Sheffield Academic Press, Sheffield, Yorkshire, England, 1999, pp. 75-99. 

Solid-Phase Microextraction Solid-phase microextraction (SPME) is a preconcentration technique based on the sorption of analytes present in a liquid phase or, more often, in a headspace gaseous phase, on a microbber coated with a chromatographic sorbent and incorporated in a microsyringe [15]. The analytes sorbed in the coating are transferred to a GC injector for thermal desorption. 

Sample analysis based on sorption onto SPE sorbents followed by elution with organic solvent is the basis of the majority of SPE methods. However, the use of fibers to sorb organic compounds directly from solution was developed by Pawliszyn and co-workers (Arthur and Pawliszyn, 1990), and devices are commercially available from Supelco (see Chapter 12 for a description of the method). The adsorbed compounds may be directly desorbed into the GC without a solvent peak by simply heating the fiber in the inlet of the gas chromatograph. Solid-phase microextraction (SPHE) has mainly been used... 

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