Solid Phase Microextraction fibre

Paschke, A. and Popp, P. 2003, Solid-phase microextraction fibre-water distribution constants of more hydrophobic organic compounds and dieir correlations widi octanol-water partition coefficients. J. Chromatogr. A 999 35-42. 

The fabrication of imprinted monolithic solid-phase microextraction fibres has been developed for the selective extraction and preconcentration of diacetylmorphine and its structural analogues, triazines, bisphenol A, anaesthetics, and antibiotics followed by GC or HPLC analysis [156,163,179,196,197]. In addition, the on-line coupling of the imprinted monolith as a preconcentration column with a conventional analytical column has been proposed for the enrichment and cleanup of environmental and food samples [163]. However, at present, the capacity of the imprinted fibres and thus the degree of recovery of analytes are very variable and obviously need some improvement. For example, the recoveries of triazines after SPME with an imprinted monolith prepared by in situ polymerisation of MAA as... 

The third alternative is the use of a Solid Phase Microextraction fibre (SPME) to collect the volatiles in the headspace. The technique is clean, very easy to use and provides a good concentration of many volatiles on the headspaces of wine. Because of this, it has been the technique of choice in some recent works (Marti et al. 2003 Fan and Qian 2005 Gurbuz et al. 2006 Tat et al. 2007). Nevertheless, the use of this technique is not exempt from problems either. On the one hand the technique does not provide an extract, and on the other hand it is quite difficult to optimize and validate and therefore to assess the reliability of the results. It should be concluded that, although the technique is appealing, more research is needed in order to establish its advantages and drawbacks. 

Spieteluna, A., Pilarczyka, M., Kloskowskia, A., Namiesnik, J. Polyethylene glycol-coated solid-phase microextraction fibres for the extraction of polar analytes—a review. Talanta 87, 1-7 (2011)... 

Adam, M. Juklova, M. Bajer, T. Eisner, A. Ventura, K (2005). Comparison of three different solid-phase microextraction fibres for analysis of essential oils in yacon... 

Zeng, J., Chen, J. and Wang, Y. (2008), Development of relatively selective, chemically and mechanically robust solid-phase microextraction fibres based on methacrylic acid-trimethylolpropane trimethacrylate co-polymers. Journal of Chromatography. A. 1208(1-2) pp. 34-41. 

Although solid-phase microextraction (SPME) has only been introduced comparatively recently (134), it has already generated much interest and popularity. SPME is based on the equilibrium between an aqueous sample and a stationary phase coated on a fibre that is mounted in a syringe-like protective holder. Eor extraction, the fibre... 

Principles and Characteristics Solid-phase microextraction (SPME) is a patented microscale adsorp-tion/desorption technique developed by Pawliszyn et al. [525-531], which represents a recent development in sample preparation and sample concentration. In SPME analytes partition from a sample into a polymeric stationary phase that is thin-coated on a fused-silica rod (typically 1 cm x 100 p,m). Several configurations of SPME have been proposed including fibre, tubing, stirrer/fan, etc. SPME was introduced as a solvent-free sample preparation technique for GC. 

Principles and Characteristics As mentioned already (Section 3.5.2) solid-phase microextraction involves the use of a micro-fibre which is exposed to the analyte(s) for a prespecified time. GC-MS is an ideal detector after SPME extraction/injection for both qualitative and quantitative analysis. For SPME-GC analysis, the fibre is forced into the chromatography capillary injector, where the entire extraction is desorbed. A high linear flow-rate of the carrier gas along the fibre is essential to ensure complete desorption of the analytes. Because no solvent is injected, and the analytes are rapidly desorbed on to the column, minimum detection limits are improved and resolution is maintained. Online coupling of conventional fibre-based SPME coupled with GC is now becoming routine. Automated SPME takes the sample directly from bottle to gas chromatograph. Split/splitless, on-column and PTV injection are compatible with SPME. SPME can also be used very effectively for sample introduction to fast GC systems, provided that a dedicated injector is used for this purpose [69,70],... 

Solid-phase microextraction has also been used for to determine volatile organic compounds in soil [26]. Target compounds were adsorbed directly from a head-space sample above a soil layer onto a fused-silica fibre. Vacuum distillation coupled with gas chromatography-mass spectrometry [27], head-... 

Sampling of these substances has been carried out following three approaches liquid absorbents [47], solid-phase microextraction (SPME) fibres [43] and filter substrates (mostly quartz fibre filters but also PTFE membranes [1, 42, 48, 49]). When filter substrates are used, atmospheric particles are collected over 24-h periods using high-volume (dichotomous or single-filter instruments [1, 48]), medium-volume or low-volume samplers (operated to ensure collection of sufficient aerosol mass [37, 50]). Samples were always stored at low temperamres (refrigerated or frozen) to ensure sample preservation. 

Ion mobility spectrometry (IMS [43]). Solid phase microextraction (SPME) using a 100 pm polydimethylsiloxane (PDMS) SPME fibre was used for head-space sampling and preconcentration of volatile markers of cocaine, MDMA and marijuana (methyl benzoate, piperonal and terpenes, respectively) in cargo containers. Analysis was then performed by IMS after thermal desorption of the drug markers from the fibre into the IMS analyser. 

Sporkert, F., Pragst, F., Huebner, S., Mills, G.G. (2002). Head-space solid-phase microextraction with 1-pyrenyldiazo-methane on-fibre derivatisation for analysis of fluoroacetic acid in biological samples. J. Chromatogr. B 772 45-51. 

A solid-phase microextraction process involves two steps, namely partitioning of the analytes between the coating and the sample, and desorption of the concentrated species into an analytical instrument. In the first step, the coated fibre is exposed and the target analytes are extracted from the sample matrix into the coating. In the second step, the fibre with the concentrated analytes is transferred to an instrument for desorption. A third, clean-up step can also be incorporated by using selective solvents, as in SPE. 

Miniaturized retention has been accomplished by using solid-phase microextraction (SPME) to collect PAHs from soil, air particulate matter and urban particulates [62,165], and pyrethrins from pyrethrum flower [165] in the fibre after quantitative extraction with superheated water [62,166]. 

Mateo-Vivaracho, L., Ferreira, V. and Cacho, J. (2006) Automated analysis of 2-methyl-3-furanethiol and 3-mercaptohexyl acetate at ng L 1 level by headspace solid phase microextraction with on-fibre derivatization and gas chromatography-negative chemical ionization mass spectrometric determination,/. Chromatogr. A, 1121(1), 1-9. 

Shirey, R.E., Optimization of extraction conditions and fibre selection for semivolatile analytes using solid-phase microextraction, J. Chromatogr. Sci., 38, 279-288 (2000)... 

Solid-phase microextraction (SPME) is the process whereby an analyte is adsorbed onto the surface of a coated-sihca fibre as a method of concentration. This is followed by desorption of the analytes into a suitable instrument for separation and quantitation. The theory of SPME is discussed in Box 8.1. 

Figure 8.13 Analysis of o-xylene and BTEX (in water) using solid-phase microextraction (a) direct SPME fibre mode (b) headspace SPME fibre mode (c) results obtained for o-xylene using mode (a) (d) results obtained for BTEX using mode (b) , no stirring IH, with stirring , with stirring, plus salt , benzene , toluene a, ethylbenzene , m-, p-xylene(s) x, o-xylene [4] (cf. DQ 8.11).

Solid-phase microextraction (SPME) A sample preparation technique that uses a fused silica fibre coated with a polymeric phase to sample either an aqueous solution or the headspace above a sample. Analytes are absorbed by the polymer coating and the SPME fibre is directly transferred to a GC injector or special HPLC injector for desorption and analysis. 

Another useful technique is solid phase microextraction. A fused silica fibre is attached to the base of a syringe with a fixed metal needle. The fibre is coated with a thin layer of stationary phase that is selective for the analytes of interest. The fibre is dipped into the liquid sample or into the headspace above the liquid for a period of time, allowing a fraction of the analyte to be extracted into the fibre. The fibre is then retracted into the syringe and the syringe injected into the injection port where the analyte is thermally desorbed from the fibre into the GC. 

Arthur, C. L, and Pawliszyn, J., 1990, Solid-phase microextraction with thermal desorption used fused silica optical fibres. Anal. Chem. 62 2145-2148. 

Rodriguez, I. et al., Qn-fibre silylation following solid-phase microextraction for the determination of acidic herbicides in water samples by gas chromatography. Anal. Chim. Acta, 537, 259, 2005. 

In SPME analytes can be adsorbed fl om a liquid sample, by immersion or headspace extraction, or from a solid sample, by headspace extraction using a polymer-coated fused silica fibre. Headspace solid-phase microextraction (HS-SPME) shortens the extraction time and facilitates analysis of solid samples, provided that the analytes are volatile. Pawliszyn et al. [992] have reported initial work on HS-SPME in 1993. These authors have evaluated theoretically and experimentally the equilibrium and kinetics of HS-SPME. 

MALDI-ToFMS has also been used in connection with solid-phase microextraction (SPME) by direct introduction of the SPME fibre and desorption of the analytes into the cavity of the ion trap [296] or by loading SPE membranes coated with matrix material [287]. Internal standardisation is required for quantitative measurement because of poor reproducibility. For this purpose preferably an isotopi-cally labelled compound should be chosen. 

Sharma N, Jain A, Verma KK (2011) Headspace solid-phase microextraction and on-fibre derivatization of primary aromatic amines for their determination by pyrolysis to aryl isothiocyanates and gas chromatography-mass spectrometry. Anal Methods 3(4) 970-976. doi 10.1039/C0AY00745E... 

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