Solid-phase microextraction procedures

G. A. Mills, V. Walker, Headspace solid phase microextraction procedures for gas chromato graphic analysis of biological fluids and materials, J. Chromatogr. A, 902, 267 287 (2000). 

Wennrich [167] optimised important accelerated solvent extraction parameters, such as extraction temperature and time, using a spiked wetland soil. The effect of small amounts of organic modifiers on the extraction yields was studied. An extraction temperature of 125 °C and ten-minute extractions performed three times proved optimal. Two accelerated solvent extraction-solid-phase microextraction procedures without and with an organic modifier (5% acetonitrile) were evaluated with respect to precision and detection limits. 

Frias, S., M.A. Rodriquez, J.E. Conde, and J.P. Perez-Trujillo (2003). Optimization of a solid-phase microextraction procedure for the determination of triazines in water with gas chromatography-mass spectrometry detection. J. Chromatogr. A, 1007 127-135. 

Abalos, M., Bayona, J. M., and Pawliszyn, J., Development of a headspace solid-phase microextraction procedure for the determination of free volatile fatty acids in waste waters, J. Chromatogr. A, 873, 107-115, 2000. 

Chai, M. K. and Tan, G. H. 2009. Validation of a headspace solid-phase microextraction procedure with gas chromatography-electron capture detection of pesticide residues in fruits and vegetables. Food Chem. 117 561-567. 

SW Lloyd, JM Lea, PV Zimba, CC Grimm. Rapid analysis of geosmin and 2-methylisoborneol in water using solid phase microextraction procedures. Water Res 32 2140-2146, 1998. 

The most widely employed techniques for the extraction of water samples for triazine compounds include liquid-liquid extraction (LLE), solid-phase extraction (SPE), and liquid-solid extraction (LSE). Although most reports involving SPE are off-line procedures, there is increasing interest and subsequently increasing numbers of reports regarding on-line SPE, the goal of which is to improve overall productivity and safety. To a lesser extent, solid-phase microextraction (SPME), supercritical fluid extraction (SEE), semi-permeable membrane device (SPMD), and molecularly imprinted polymer (MIP) techniques have been reported. 

Solid-phase microextraction (SPME) consists of dipping a fiber into an aqueous sample to adsorb the analytes followed by thermal desorption into the carrier stream for GC, or, if the analytes are thermally labile, they can be desorbed into the mobile phase for LC. Examples of commercially available fibers include 100-qm PDMS, 65-qm Carbowax-divinylbenzene (CW-DVB), 75-qm Carboxen-polydimethylsiloxane (CX-PDMS), and 85-qm polyacrylate, the last being more suitable for the determination of triazines. The LCDs can be as low as 0.1 qgL Since the quantity of analyte adsorbed on the fiber is based on equilibrium rather than extraction, procedural recovery cannot be assessed on the basis of percentage extraction. The robustness and sensitivity of the technique were demonstrated in an inter-laboratory validation study for several parent triazines and DEA and DIA. A 65-qm CW-DVB fiber was employed for analyte adsorption followed by desorption into the injection port (split/splitless) of a gas chromatograph. The sample was adjusted to neutral pH, and sodium chloride was added to obtain a concentration of 0.3 g During continuous... 

Experiments to identify disinfection by-products (DBFs) have been carried out using two different procedures. In the first, natural waters (e.g., river, lake) are reacted with the disinfectant, either in a pilot plant, an actual treatment plant, or in a controlled laboratory smdy. fii the second type of procedure, aquatic humic material is isolated and reacted with the disinfectant in purified water in a controlled laboratory study. This latter type of study is relevant because humic material is an important precursor of THMs and other DBFs. Aquatic humic material is present in nearly all natural waters, and isolated humic material reacts with disinfectants to produce most of the same DBFs found from natural waters. Because DBFs are typically formed at low levels (ng/L-pg/L), samples are usually concentrated to allow for DBF detection. Concentration methods that are commonly used include solid phase extraction (SFE), solid phase microextraction (SFME), liquid-liquid extraction, and XAD resin extraction (for larger quantities of water) [9]. 

In this work, we adapted a method for the analysis of beer aldehydes using solid-phase microextraction (SPMF) with on-fiber derivatization. This extraction technique does not require solvents, consists of a one-step sample preparation procedure, and provides high sensitivity and reproducibility. It enabled a detailed study of aldehyde level changes during packaged beer storage. 

A fourth example (P17) is from the Introduction section of the article that examines PCBs in full-fat milk. For background information, the authors outline the general four-step procedure used to determine PCBs in full-fat milk. Conventional methods used to accomplish two of these steps, extraction and cleanup, are also described. In a new paragraph, the authors introduce solid-phase microextraction (SPME), a technique that greatly simplifies this four-step process. But SPME is not recommended for complex matrixes hence, the authors motivate the topic of their current paper, headspace mode SPME (HSSPME). 

Objective. To date, there is no simple or rapid procedure for testing PCBs in milk. Headspace solid-phase microextraction (HSSPME) is a promising approach, but only a few works have applied this technique to milk (1, 2). Here, we present a simple and rapid saponification-HSSPME procedure for extracting PCBs from milk. (119 words)... 

Recently, the procedures that are suitable to isolate the volatile fraction of a sample under mild conditions have been reviewed [1]. Three techniques—solvent extraction, distillation and solid-phase microextraction (SPME)—will be presented here. 

A. M. Carro, I. Neira, R. Rodil and R. A. Lorenzo, Speciation of mercury compounds by gas chromatography with atomic emission detection. Simultaneous optimisation of a headspace solid-phase microextraction and derivatisation procedure by use of chemometric techniques, Chro-matographia, 56(11/12), 2002, 733-738. 

Here is a student procedure to measure nicotine in urine. A 1.00-mL sample of biological fluid was placed in a 12-mL vial containing 0.7 g Na2CO , powder. After 5.00 pig of the internal standard 5-aminoquinoline were injected, the vial was capped with a Teflon-coated silicone rubber septum. The vial was heated to 80°C for 20 min and then a solid-phase microextraction needle was passed through the septum and left in the headspace for 5.00 min. The fiber was retracted and inserted into a gas chromatograph. Volatile substances were desorbed from the fiber at 250°C for 9.5 min in the injection port while the column was at 60°C. The column temperature was then raised to 260°C at 25°C/min and eluate was monitored by electron ionization mass spectrometry with selected ion monitoring at m/z 84 for nicotine and m/z 144 for internal standard. Calibration data from replicate... 

The time required for quantification of volatiles by both the Basic Protocol and the Alternate Protocol depends on the isolation/extrac-tion procedure chosen. A complete homogenization of the labeled standards with the sample usually requires not more than 30 min and GC-MS analysis is accomplished within 1 hr. In combination with a high-throughput method like solid-phase microextraction, the GC cycle times (-1 hr) become the limiting factor in the quantification of multiple samples by IDAs. 

MEPS has so far been applied mainly to the analysis of drugs in biological samples only one application for the extraction of PAHs in water has been published.26 One of the major advantages of the MEPS design is that the packed syringe can be used many times over, for example, more than 400 times for water samples. Moreover, the technique permits a fast handling time in the analysis of PAHs in water, the speed enhancement being 15 and 100 times compared to the literature procedures of solid-phase microextraction (SPME) and stir bar sorptive extraction (SBSE), respectively see Sections 4.2.3 and 4.2.4. 

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). 

A. Alcaraz, S.S. Hulsey, R.E. Whipple and B.D. Andresen, On-site sample work-up procedures to isolate chemical warfare related compounds using solid phase extraction and solid phase microextraction technology, NATO ASI Ser. Ser. 1, 13, 65-76 (1997). 

Aroma compounds from vanilla beans have been extracted using several extraction procedures, using alcohols and organic solvents (Galletto and Hoffman, 1978 Dignum et al., 2002), direct thermal desorption (Hartman et al., 1992 Adedeji et al., 1993) and solid-phase microextraction (SPME) (Sostaric etal., 2000), followed by identification of the compounds by gas chromatography-mass spectrometry (GC-MS). 

Solid-phase microextraction (SPME) — is a procedure originally developed for sample preconcentration in gas chromatography (GC). In this procedure a small-diameter fused silica optical fiber, coated with a liquid polymer phase such as poly(dimethylsiloxane), is immersed in an aqueous sample solution. The -> analytes partition into the polymer phase and are then thermally desorbed in the GC injector on the column. The same polymer coating is used as a stationary phase of capillary GC columns. The extraction is a non-exhaustive liquid-liquid extraction with the convenience that the organic phase is attached to the fiber. This fiber is contained in a syringe, which protects it and simplifies introduction of the fiber into a GC injector. Both uncoated and coated fibers with films of different GC stationary phases can be used. SPME can be successfully applied to the analysis of volatile chlorinated organic compounds, such as chlorinated organic solvents and substituted benzenes as well as nonvolatile chlorinated biphenyls. 

Extraction procedures of plant materials classical percolation, maceration, digestion, decoction, and so on, as well as supercritical fluid extraction, microwave-assisted extraction, pressurized solvent extraction, and solid-phase microextraction are described. Eor biological matrices, liquid-liquid, and solid phase extractions are mainly used for different samples such as blood, urine, microdialysates, and saliva, among others. 

Lopez, R., Lapena, A.C., Cacho, J., and Ferreira, V. (2007). Quantitative determination of wine highly volatile sulfur compounds by using automated headspace solid-phase microextraction and gas chromatography-pulsed flame photometric detection - Critical study and optimization of a new procedure. J. Chromatogr. A., 1143, 8-15. 

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