Solid-phase microextraction principles

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],... 

Young and Her [159] used the principle of solid-phase microextraction combined with Fourier transform infrared sensing to determine chlorinated... 

Pawliszyn J (ed) (1999) Applications of solid phase microextraction, RSC Chromatography monographs. The Royal Society of Chemistry, Cambridge, UK Hakkarainen M, Albertsson A-C (2005) Biomacromolecules 6 775 Hakkarainen M, Burman L, Albertsson A-C (2006) In Khemani K, Scholz C (eds) ACS Symp Series No 939 Degradable Polymers and Materials Principles and Practice, Chapter 19, Amer Chemical Soc, Washington, USA, p 307 Hakkarainen M, Karlsson S, Albertsson A-C (1999) Polymer 41 2331 Albertsson A-C, Erlandsson B, Hakkarainen M, Karlsson S (1998) J Environ Polym Degrad 6 187... 

The extraction techniques described in this book fulfill many of Anastas and Warner s principles. For example, the use of supercritical carbon dioxide (SC-CO2) as the sole extraction solvent results in a nonpolluting process (prevention of waste and safer solvents and auxiliaries). Other beneficial properties of supercritical CO2 include fast diffusivity and nearly zero surface tension, which lead to extremely efficient extractions. In Chapters 2-4, applications of SC-CO2 as an extraction solvent are described. Ethanol and water are also environmentally friendly solvents that can be used as extraction media in many applications (see Chapters 5-7). Pressurized hot water ( 100-200 °C) in particular is a safe and nonpolluting solvent that has a similar dielectric constant to polar organic solvents, such as ethanol or acetone. Hence, pressurized hot water is a viable green alternative to many current extraction processes that use toxic organic solvents. Similarly, pressurized hot ethanol is an excellent solvent for the extraction of most medium polar to nonpolar organic molecules. Some of the techniques, such as membrane-assisted solvent extraction, described in Chapter 10, use organic solvents but in much smaller amounts compared to classical extraction techniques. Other techniques, for instance solid-phase microextraction and stir-bar sorptive extraction, described in Chapter 11, use no solvents. 

A chapter in a popular book on HPLC nicely presents SPE (57). Two texts have recently been published on the principles and practice of SPE (58). Recently, a special issue of LC-GC The Magazine of Separation Science was devoted to sample preparation and included articles that addressed not only conventional SPE but included automated SPE, martix solid-phase dispersion, membrane filtration, solid-phase microextraction, and polymeric RP-SPE sorbents (59). Cahners Business Information, that publishes R D Magazine has recently started a monthly newsletter titled Sample Preparation largely as a means to showcase products related to SPE and related techniques. 

See also Extraction Solvent Extraction Principles Solid-Phase Microextraction. 

See also Extraction Solvent Extraction Principles Solid-Phase Extraction Solid-Phase Microextraction. Flow Injection Analysis Principles Instrumentation. Ion Exchange Principles. Ion-Selective Electrodes Liquid Membrane Gas Sensing Probes Enzyme Electrodes. Membrane Techniques Dialysis and Reverse Osmosis Ultrafiltration Pervaporation. Solvents. 

Distillation. Essential Oils. Extraction Solvent Extraction Principles Solid-Phase Extraction Solid-Phase Microextraction. Gas Chromatography Detectors Mass Spectrometry Chiral Separations. Headspace Analysis Static Purge and Trap. Mass Spectrometry Principles Selected Ion Monitoring. Quality Assurance Quality Control. Sensors Overview. 

See also Atomic Absorption Spectrometry Principles and Instrumentation. Atomic Emission Spectrometry Inductively Coupled Plasma. Cosmetics and Toiletries. Derivatization of Analytes. Electrophoresis Is-otachophoresls. Environmental Analysis. Enzymes Overview. Extraction Supercritical Fluid Extraction Solid-Phase Extraction Solid-Phase Microextraction. Ion Exchange Ion Chromatography Applications. Liquid Chromatography Reversed Phase Liquid Chromatography-Mass Spectrometry. Nuclear Magnetic Resonance Spectroscopy - Applicable Elements Carbon-13 Phosphorus-31. Perfumes. 

See also Atomic Absorption Spectrometry Interferences and Background Correction. Atomic Emission Spectrometry Principles and Instrumentation Interferences and Background Correction Flame Photometry Inductively Coupled Plasma Microwave-Induced Plasma. Atomic Mass Spectrometry Inductively Coupled Plasma Laser Microprobe. Countercurrent Chromatography Solvent Extraction with a Helical Column. Derivatization of Analytes. Elemental Speciation Overview Practicalities and Instrumentation. Extraction Solvent Extraction Principles Solvent Extraction Multistage Countercurrent Distribution Microwave-Assisted Solvent Extraction Pressurized Fluid Extraction Solid-Phase Extraction Solid-Phase Microextraction. Gas Chromatography Ovenriew. Isotope Dilution Analysis. Liquid Chromatography Ovenriew. 

Improved sensor respraise to several organic species can be achieved by exploiting the high adsorption capability of carbon surfaces, in adsorptive stripping voltammetry (AdSV). This procedure, based on very similar principles of solid phase microextraction (SPME), implies that analytes are pre-concentrated at carbon nanostructured surfaces prior to voltammetric detection. It has been successfully... 

Principles and Characteristics Normally, analysis of solid materials prior to chromatographic separation and detection requires some form of extraction with organic solvents, either by heating (Soxhlet, Soxtec, etc), agitation (sonication or shake-flask extraction) of the organic solvent-solid mixture, or by more recently introduced techniques (MAE, SEE, ASE ). In particular the latter approaches are costly in terms of equipment. It has been shown that solid-phase microextraction (SPME) can also be utilised for direct analysis of solids [991]. 

Analysis of volatiles is frequently utilised in food industry to quality control food products and to determine shelf-life for various products. Some recent examples are the use of sensor arrays to differentiate milk products according to their aging times (12) and the use of solid phase microextraction-mass spectrometry-multivariate data system to predict the shelf-life of pasteurised milk (13). Volatiles emitted by plants have also been correlated to abiotic or biotic stress and the degree of damage caused by the stress (14). Similar principles should be applicable to polymeric materials i.e. the formation of certain volatiles or indicator products during degradation of the polymer is related to the changes in the polymer matrix (Fig. 1). 

The stir bar sorptive extraction (SBSE) is a relatively new preconcentration and solventless extraction method that was Irrst described in 1999 by Baltussen et al. [211], and further developed. SBSE is based on the same principles than the solid-phase microextraction (SPME) and relies in the partitioning of the analytes between a sample and a polymeric sorbent, followed by desorption of the analytes retained in the sorbent into an appropriate analytical system. 

Some of the newer procedures use the same basic principles as the older extraction methods but provide fast and easy-to-use options and generally consume less organic solvent. For the most part, they have higher initial purchase price than the traditional methods. Examples include supercritical fluid extraction, accelerated solvent extraction, and automated solid-phase extraction and microextraction. Modular systems are now readily available that automate these proce-... 

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