Stir-bar sorptive extraction

Koster et al. [140] conducted on-fiber derivatization for SPME to increase the detectability and extractability of drugs in biological samples. Amphetamine was used as a model compound. The extraction was performed by direct immersion of a 100-pm polydimethylsiloxane-coated fiber into buffered human urine. On-fiber derivatization was performed with pentafluorobenzoyl chloride either after or simultaneously with extraction. 

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). 

The stir bar technique has been applied to headspace sorptive extraction (HSSE) [142-144], However, headspace techniques are discussed elsewhere, as they are more applicable to volatile organic compounds than to the semivolatile organic compounds that comprise the focus of this chapter. 

Another recently developed technique is headspace sorptive extraction (HSSE) with PDMS stir bars [552]. HSSE-GC was compared with SHS and HS-SPME. SBSE and HSSE extract organic analytes from aqueous or vapour samples. In SBSE, the stir bar is inserted into the aqueous sample and extraction takes place during stirring whereas in HSSE the glass rod is suspended within the headspace volume and sampling takes place during headspace equilibration. New trends are the development of selective sorbents. 

The conventional polymeric coating, PDMS, employed in SPME has a film thickness of 100 pm, which corresponds to a volume of about 0.5 pL for the whole fiber. In SPME, the thin PDMS film provides the highest enrichment when equilibrium between the film and sample is realized, the attainment of which depends largely on analyte hydrophobicity and distribution to the coating. With thin PDMS films, SPME does not generally afford quantitative exhaustive extraction, which renders SPME a less sensitive technique even for nonpolar compounds and an unsatisfactory sampling device that fails to extract polar analytes. Implementing SPME for total exhaustive extraction is conceivably plausible if the PDMS film thickness is increased dramatically. 

Since only PDMS coating is available as an extraction phase, SBSE has been used predominantly for low-polarity analytes, but the problems of extraction of polar compounds may be solved by in situ derivatiziation. It is clear that further developments in stir bar coatings and designs could extend the applicability of the method. The main drawback of this method is the duration of extraction, typically 30-150 min. For this reason SBSE may be impractical for routine high-throughput laboratories. 

Huang et al. described a simple, rapid method for the quantitative monitoring of five sulfonamide antibacterial residues in milk. The analytes were concentrated by SBSE based on poly(vinylimidazole-divinylbenzene) monolithic material as coating, and analyzed by HPLC with diode-array detection. The extraction procedure was very simple. Milk was first diluted with water and then directly subjected to sorptive extraction without a requirement for additional steps to eliminate fats and protein in the samples. Under the optimized experimental conditions, low detection limits (S/N = 3) (where S/N = signal-to-noise ratio) and quantification limits (S/N = 10) were achieved for the target compounds within the range of 1.30-7.90 and 4.29-26.3 p.g/1 from spiked milk, respectively. Good linearities were obtained for the sulfonamides with correlation coefficients (R ) above 0.996. Finally, the proposed method was successfully applied to the determination of sulfonamides in different milk samples. 

Luo et al. described a stirring rod (instead of stir bar) sorptive extraction (SRSE). A rod with monolithic polymer as coating was proposed to avoid the 

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To overcome the problems of relatively low sample capacity associated with SPME, a technique known as stir-bar sorptive extraction has been reported by Baltussen etal. A glass-coated magnetic stir bar was coated with 50-100 iL of PDMS. Sample extraction was performed by placing the stir bar in the sample with subsequent stirring for 30-120 min. After extraction, the stir bar was removed and analytes were thermally desorbed at 150-300 °C for 5 min for GC, or liquid desorbed for LC. Qualitative analysis of organochlorine residues in wine has been reported using a commercially available product known as Twister. ... 

Miniaturisation of scientific instruments, following on from size reduction of electronic devices, has recently been hyped up in analytical chemistry (Tables 10.19 and 10.20). Typical examples of miniaturisation in sample preparation techniques are micro liquid-liquid extraction (in-vial extraction), ambient static headspace and disc cartridge SPE, solid-phase microextraction (SPME) and stir bar sorptive extraction (SBSE). A main driving force for miniaturisation is the possibility to use MS detection. Also, standard laboratory instrumentation such as GC, HPLC [88] and MS is being miniaturised. Miniaturisation of the LC system is compulsory, because the pressure to decrease solvent usage continues. Quite obviously, compact detectors, such as ECD, LIF, UV (and preferably also MS), are welcome. 

PLE pressurized liquid extraction, SPE solid phase extraction, UE ultrasonic extraction, DSPE dispersive solid phase extraction, SBSE stir bar sorptive extraction, TD-GC-MS thermal desorption-gas chromatography-mass spectrometry, LAS linear alkylbenzene sulfonates, CDEAs coconut diethanol amides, NPEOs nonylphenol ethoxylates, DP degradation products, SPC sulphenyl carboxylates, PCDD dibenzo-p-dioxins (PCDD), PCDF dibenzofurans, PCBs biphenyls... 

Rodil R, Moeder M (2008) Development of a method for the determination of UV filters in water samples using stir bar sorptive extraction and thermal desorption-gas chromatography-mass spectrometry. J Chromatogr A 1179(2) 81—88... 

Tan BL, Hawker DW, Muller JF, Tremblay LA, Chapman HF (2008) Stir bar sorptive extraction and trace analysis of selected endocrine disrupters in water, biosolids and sludge samples by thermal desorption with gas chromatography-mass spectrometry. Water Res 42 404 112... 

Bicchi, C., loti, C., Rubiolo, P. and Sandra, P. (2002) Headspace sorptive extraction (HSSE), stir bar sorptive extraction (SBSE) and solid phase microextraction (SPME) applied to the analysis of roasted Arabica coffee and coffee brew. J.Agric. Food Chem. 50, 449-459. 

Soini, H.A., Bruce, K.E., Wiesler, D., David, F., Sandra, P. and Novotny, M.V. (2005) Stir bar sorptive extraction a new quantitative and comprehensive sampling technique for determination of chemical signal profiles from biological media J. Chem. Ecol., 31, 377-392. 

Abstract A relatively small number of mammalian pheromones has been identified, in contrast to a plethora of known insect pheromones, but two remarkable Asian elephant/insect pheromonal linkages have been elucidated, namely, (Z)-7-dodecen-1-yl acetate and frontalin. In addition, behavioral bioassays have demonstrated the presence of a chemical signal in the urine of female African elephants around the time of ovulation. Our search for possible ovulatory pheromones in the headspace over female African elephant urine has revealed for the first time the presence of a number of known insect pheromones. This search has been facilitated by the use of a powerful new analytical technique, automated solid phase dynamic extraction (SPDE)/GC-MS, as well as by novel macros for enhanced and rapid comparison of multiple mass spectral data files from Agilent ChemStation . This chapter will focus on our methodologies and results, as well as on a comparison of SPDE and the more established techniques of solid phase microextraction (SPME) and stir bar sorptive extraction (SBSE). 

Stir bar sorptive extraction (SBSE) is a more recent development, and offers some advantages over SPME (Baltussen, Sandra, David and Cramers 1999 ... 

Baltussen, E., Sandra, P., David, F. and Cramers, C. (1999) Stir bar sorptive extraction (SBSE), a novel extraction technique for aqueous samples theory and principles. J. Microcolumn Sep. 11,737-747. 

Tienpont, B., David, F., Desmet, K. and Sandra, P. (2002) Stir bar sorptive extraction-Thermal desorption-capillary GC-MS applied to biological fluids. Anal. Bioanal. Chem. 373, 46-55. 

Besides classical headspace analysis, simultaneous distillation-extraction and solvent extraction, new sampling and enrichment developments include solvent-assisted flavour evaporation (SAFE) [3] and sorptive techniques like SPME solid-phase microextraction (SPME) [4,5] and stir-bar sorptive extraction (SBSE) [6], which are treated in a dedicated chapter in this book. This contribution will deal with advanced developments of GC techniques for improvement of separation and identification (classical multidimensional GC, or... 

Kreck, M., Scharrer, A., Bilke, S., Mosandl, A. (2002) Enantioselective analysis of monoter-pene compounds in essential oils by stir bar sorptive extraction (SBSE)-enantio-MDGC-MS. Flavour Fragrance ]. 17 32-40. 

Stir-Bar Sorptive Extraction-Enantioselective Multidimensional Gas Chromatography-Mass Spectrometry... 

A novel solventless simple technique for extraction of organic analytes from aqueous samples, stir-bar sorptive extraction (SBSE), was introduced by Baltus-sen et al. [41]. 

Fig. 17.10 Stir-bar sorptive extraction-enantio-MDGC-MS analysis of tea tree oil, main column separation [45]...

Bicchi C, Cordero C, lori C, Rubiolo P, Sandra P (2000) Headspace sorptive extraction (HSSE) in the headspace analysis of aromatic and medicinal plants. J High Resol Chromatogr 23 539 KreckM, Scharrer A, Bilke S, Mosandl A (2001) Stir bar sorptive extraction (SBSE)—enantio-MDGC-MS, a rapid method for the enantioselective analysis of chiral flavour compoimds in strawberries. Eur Food Res Technol 213 389... 

Stir-bar sorptive extraction (SBSE) is carried out using a commercially available glass stir bar (Twister, from Gerstel GmbH) coated with polydimethylsiloxane (PDMS). A special thermal desorption unit is necessary to introduce the extract into a GC. It can be applied to headspace extraction, but is intended for stirring liquid samples for extraction. The same coatings used for SPME can be used for SBSE, and thus similar selectivity should be observed. 

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