Solid-phase micro-extraction

3 Solid Phase Micro-extraction Solid phase micro-extraction (SPME) was developed in 1989 by Pawliszyn and coworkers ° ° as a simple and effective adsorption/adsorption and desorption technique that eliminates the need for solvents. Applications of SPME in the analysis of drugs have been reviewed, as well as the possibilities of interfacing SPME with HPLC. ° SPME 

In bio-analytical methods, both direct-immersion (DI-SPME) and head-space fiber (HS-SPME) have been applied with or without a derivatization step. Using the direct immersion approach, which means exposure of the fiber to the sample in solution, clenbuterol in urine and serum as well as citalopram, fluoxetine, and their main metabolites in urine, were determined without a derivatization step by HPLC analysis. 

The outstanding advantage of HS-SPME in bio-analytical methods is the prevention of direct contact of the fiber with the sample, and therefore the prevention of contamination of the surface of the fiber with organic polymers. However, the use of the fiber HS-SPME technique is limited to only analytes that have a suitably high vapor pressure. Eurthermore, the transfer of fibers to the GC as well as desorption should be performed immediately after extraction because the high vapor pressure poses a risk of analyte loss during storage of the loaded fiber. 

There are some principal disadvantages that limit the use of fiber SPME. These include fhe limited capacity of SPME fiber and a requiremenf for a very low initial temperature for GC temperature programs because of the necessity of cryofocusing of the analyte, thus prolonging GC analysis time. In addition, desorption takes more time than in the injection of LEE or SPE extracts, and carryover effects occur very easily. As SPME is by nature a dirty extraction, quantification is more prone to errors due to changes in the matrix even when internal standards are used. Finally, SPME fiber is quite fragile. Because of these restrictions and limitations, fiber SPME is not a universal sample preparation method, especially not in bio-analytical laboratories, and is unlikely to become so in the future. 

However, the development and investigation of new sorbent materials for use in extraction and SPME techniques is both a growing and promising field. The compilation 

---

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). 

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. 

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. 

Classical sample preparation methods such as distillation, soxhlet extraction are still used [839, 840], but specific techniques such as supercritical fluid extraction (SFE) [841], and increasingly in recent years, adsorption techniques such as solid phase micro-extraction (SPME) [841a] are also being used for isolation, separation, and identification of flavor and fragrance materials. 

Adahchour, M., Wiewel, J., Verdel, R., Vreuls, R.J.J., Brinkman, U.A.T. (2005) Improved determination of flavour compounds in butter by solid-phase (micro) extraction and comprehensive two-dimensional gas chromatography. J. Chromatogr. A 1086 99-106. 

Solid-phase micro-extraction (SPME), a technique commercialised by Supelco, borrows from column extraction and headspace analysis. In this procedure, a small fibre fixed to the end of a syringe plunger can either exit from or be retracted into... 

---