Micro extraction

COMPUTER-AIDEDDESIGNANDMANUFACTURING(CAD/CAM)] (Vol7) Sokd-phase micro extraction... 

Solid phase micro extraction (SPME) is a techniques in which a silica fiber coated with a thin film of polymer is brought into contact with an aqueous matrix where the organics in solution partition onto the fiber. The fiber is subsequently placed into the injector of a GC where the heat causes the release of analyte onto the column. This has been applied to endosulfan (a- and (3-) and endosulfan sulfate in water with limits of detection of less than 0.3 pg/L reported (Magdic and Pawliszyn 1996). 

Figure 8.7 Apparatus for aicroaethods of solvent extraction. A, micro extraction apparatus B, Keele aicro-reactor C, Mixor phase separation device.

Applications Coupling of solid-phase micro-extraction and a micro-GC (separation times of 15 sec) is suitable for rapid field screening and potentially useful for process analysis. Odours at ppt level can be analysed by... 

E. E. Stashenko, J. R. Martinez, Sampling volatile compounds from natural products with headspace/solid phase micro extraction, J. Biochem. Biophys. Methods, 70, 235 242 (2007). 

F. De Angelis, A. Di Tullio, G. Mellerio, R. Quaresima, R. Volpe, Investigation by solid phase micro extraction and gas chromatography/mass spectrometry of organic films on stone monu ments, Rapid Commun. Mass Spectrom., 13, 895 900 (1999). 

M. van Bommel, B. van Elst, F. Broekens, Emission of organic acids from wooden construction materials in a small test chamber preliminary results of optimisation of the solid phase micro extraction technique, 4th Meeting of the Indoor Air Pollution Working Group, Copenhagen, 2001. 

S. Hamm, E. Lesellier, J. Bleton, A. Tchapla, Optimization of headspace solid phase micro extraction for gas chromatography/mass spectrometry analysis of widely different volatility and polarity terpenoids in olibanum, J. Chromatogr. A, 1018, 73 83 (2003). 

Complex matrixes typically cannot be analysed directly to obtain the selectivity and sensitivity required for most trace analysis applications. To circumvent this problem, solid-phase micro extraction techniques were used to preconcentrate analytes selectively prior to gas chromatography/ion trap mass spectrometry analysis. 

To determine organotin compounds in amounts down to 1 - 5 ng/1, McAvoy et al. [ 129] ethylated the seawater, isolated organotin solid-phase micro extraction and determined it by micro capillary GCMS. 

Solid-Phase Micro extraction (SPME) Sampling... 

The volatile substances were extracted from portions of 0. lg hair using solid-phase micro extraction (SPME). The method uses a fibre coated with an adsorbent that can extract organic compounds from the headspace above the sample. Extracted compounds are desorbed upon exposure of the SPME fibre in the heated injector port of a gas chromatograph (GC). 

In environmental analytical applications where analyte concentrations, e.g. surfactants or their metabolites, are quite low, extraction and concentration steps become essential. Solid phase extraction (SPE) with cartridges, disks or SPME fibres (solid phase micro extraction) because of its good variety of SP materials available has become the method of choice for the analysis of surfactants in water samples in combination with FIA as well as LC—MS analysis. SPE followed by sequential selective elution provides far-reaching pre-separations if eluents with different polarities and their mixtures are applied. The compounds under these conditions are separated in the MS spectrometer by their m/z ratios providing an overview of the ionisable compounds contained in a sample. Identification in the sense it has been mentioned before, however, requires the generation of fragments. 

The use of solid-phase micro-extraction (SPME) for the qualitative and quantitative determination of LAS in wastewater samples was investigated by Ceglarek et al. [7]. When examining the effect of salt addition on the extraction efficiency, NaCl, commonly used in SPME to improve extraction yields, turned out to be unsuitable because of the formation of [(NaCl) CiP clusters in the ESI-MS (prior to injection LAS was desorbed from the fibre by methanolAvater (50 50)), the formation of which were assumed to be responsible for the quantitative suppression of the LAS signals. These quenching effects were excluded when using ammonium acetate instead of NaCl. 

Pawliszyn J (1997) Sohd phase micro extraction. Theory and practice. Wiley-VCH, New York... 

The mass of sample taken for analysis is primarily dependent on four factors (1) the amount of material available, (2) the concentration of the analyte, (3) the heterogeneity of the sample, and (4) the method of analysis. Most conventional solvent extraction techniques currently start with more sample than is required, use more extraction solvent than is necessary, and ultimately only analyze 0.1% of the material prepared, e.g., 1 pi from 1 ml. Micro-extraction techniques [468] can be used in conjunction with on-line LC-GC or LC-MS to utilize the whole extract in the final determinations. This approach can significantly reduce the size of sample required and the volume of solvent used. Many workers have reported the use of solid phase microextraction (SPME) in different environmental matrices for various pollutants [288,342,345,469 - 477]. 

Yonamine M, TawU N, Moreau RL, Silva OA. 2003. Solid-phase micro-extraction-gas chromatography-mass spectrometry and headspace-gas chromatography of tetrahydrocannabinol, amphetamine, methamphetamine, cocaine and ethanol in saliva samples. J Chromatogr B Anal Technol Biomed Life Sci 789 73. 

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