Sample solventless

Extraction or dissolution almost invariably will cause low-MW material in a polymer to be present to some extent in the solution to be chromatographed. Solvent peaks interfere especially in trace analysis solvent impurities also may interfere. For identification or determination of residual solvents in polymers it is mandatory to use solventless methods of analysis so as not to confuse solvents in which the sample is dissolved for analysis with residual solvents in the sample. Gas chromatographic methods for the analysis of some low-boiling substances in the manufacture of polyester polymers have been reviewed [129]. The contents of residual solvents (CH2C12, CgHsCI) and monomers (bisphenol A, dichlorodiphenyl sulfone) in commercial polycarbonates and polysulfones were determined. Also residual monomers in PVAc latices were analysed by GC methods [130]. GC was also... 

An excellent review of modern sorptive sampling techniques that could be considered for the enrichment of volatiles from mammalian secretions appeared recently [10]. To be on the safe side, more than one sample preparation and sample enrichment method should be used to analyze mammalian secretions. If GC and GC-MS analyses are employed, the results obtained with split/split-less, on-column, SPME and solventless (solid) sample introduction methods [11,12] should be compared. 

A new, fast, sensitive, and solventless extraction technique was developed in order to analyze beer carbonyl compounds. The method was based on solid-phase microextraction with on-fiber derivatization. A derivatization agent, 0-(2,3,4,5,6-pentafluorobenzyl) hydroxylamine (PFBOA), was absorbed onto a divinyl benzene/poly(dimethylsiloxane) 65- xm fiber and exposed to the headspace of a vial with a beer sample. Carbonyl compounds selectively reacted with PFBOA, and the oximes formed were desorbed into a gas chromatograph injection port and quantified by mass spectrometry. This method provided very high reproducibility and linearity When it was used for the analysis of aged beers, nine aldehydes were detected 2-methylpropanal, 2-methylbutanal, 3-methylbutanal, pentanal, hexanal, furfural, methional, phenylacetaldehyde, and (E)-2-nonenal. (107 words)... 

Solid-phase microextraction (SPME), a new solvent-free sample preparation technique, was invented by C. Arthur and J. Pawliszyn in 1990. This method was mainly applied for the extraction of volatile and semivolatile organic pollutants in water samples. However, since 1995, SPME has been developed to various biological samples, such as whole blood, plasma, urine, hair, and breath, in order to extract drags and poisons in forensic field. The main advantages of SPME are high sensitivity, solventless, small sample volume, simplicity, and rapidity (Liu et al., 1998). 

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]. 

Several manufacturers of gas chromatographs now offer all glass splitters for use with glass capillary columns. Figure 6.13 is one design available. Splitters are generally used for solventless samples and also in petroleum and petro-chemistry a and for the analysis of essential oils. 

This technique is, of course, only applicable to organic compounds in soil that are sufficiently volatile at room temperature or slightly above that they exist in the headspace above the samples. For such samples, the technique is elegant in that it is solventless, i.e., there is no solvent interference, is amenable to automation, and can be directly coupled to a gas chromatograph and/or alternate techniques such as mass spectrometry to ensure equivocal identification of the organics. 

Wardencki, W., J. Curylo, and J. Namiesnik. 2007. Trends in solventless sample preparation techniques for environmental analysis. J. Biochem. Biophys. Methods 70 275-288. 

There is an urgent need to evaluate the analytical procedures in current use, not only with respect to the reagents, instrumental costs, and analytical parameters, but also in the context of their adverse effect on the environment. The continual development of new solventless sample preparation methods is a good example of activities in this field. Indeed, recent years have witnessed particularly rapid progress in the development of these techniques,36 37 which provide higher yields, better sample cleanup, cost effectiveness and chemist safety, and are also less harmful to the environment. 

SPME is a fast, universal, sensitive, solventless, and economical method of preparing samples for GC or HPLC analysis, enabling detection limits at a level of 5-50 ppt for volatile, semivolatile, and nonvolatile compounds to be achieved. The approximate sample preparation time is usually 2-15 min.49-50... 

Namiesnik, J. and W. Wardencki. 2000. Solventless sample preparation techniques in environmental analysis. J. High Resolut. Chromatogr. 23 297-303. 

One of the major advantages of SPME is that it is a solventless sample preparation procedure, so solvent disposal is eliminated [68,131], SPME is a relatively simple, straightforward procedure involving only sorption and desorption [132], SPME is compatible with chromatographic analytical systems, and the process is easily automated [131,133], SPME sampling devices are portable, thereby enabling their use in field monitoring. 

Solid-phase microextraction (SPME) is a fast and solventless modification of SPE techniques [20]. SPME involves the use of fiber (fused silica fiber or polymer-coated fused fiber) coated by an adsorbent. The method is applied for extraction of different kinds of both volatile and nonvolatile analytes from different kinds of media, which can be in liquid or gas phase. In the direct extraction mode, coated fiber is immersed in the sample for a defined time, until equilibrium between the sample matrix and the solid phase is reached. The analyte is transported by diffusion directly to the extracting phase. In the next stage, the compound of interest... 

Recently, SPME has provided many improvements as the cleanup step of complex samples, particularly for the analysis of volatile compounds by headspace techniques [8]. SPME is a solventless extraction and concentration technique which has advantages as a simple and economic technique that reduces health hazards and environmental issues. 

Solid-phase microextraction (SPME) is a technique that was first reported by Louch et al. in 1991 (35). This is a sample preparation technique that has been applied to trace analysis methods such as the analysis of flavor components, residual solvents, pesticides, leaching packaging components, or any other volatile organic compounds. It is limited to gas chromatography methods because the sample must be desorbed by thermal means. A fused silica fiber that was previously coated with a liquid polymer film is exposed to an aqueous sample. After adsorption of the analyte onto the coated fiber is allowed to come to equilibrium, the fiber is withdrawn from the sample and placed directly into the heated injection port of a gas chromatograph. The heat causes desorption of the analyte and other components from the fiber and the mixture is quantitatively or qualitatively analyzed by GC. This preparation technique allows for selective and solventless GC injections. Selectivity and time to equilibration can be altered by changing the characteristics of the film coat. 

SBSE has many similarities to SPME, as it is also a solventless sample preparation technique and it uses similar sorbents (based on PDMS). SBSE was first described by Baltussen and co-workers in 1999 (78). In SBSE, an aqueous sample is extracted by stirring for a certain time with a PDMS-coated stir-bar. The stir-bar is therea r removed from the sample and the absorbed compounds are then either thermally desorbed and analyzed by GC-MS, or desorbed by means of a liquid for interfacing to a LC system. Heat-desorption gives higher sensitivity while liquid desorption provides higher selectivity. 

The number of on-line methods using solvent/fiuid extraction developed for the analysis of solid food and agricultural samples is still small. The solventless... 

A dominant trend in sample preparation and extraction is miniaturization and for more than a decade now various solventless or solvent-reduced extraction methods based on a micro scale approach have been developed. 

SPME is a solventless sample preparation technique that can be applied to the analysis of BTEX in water, air, and soils. In SPME, analytes from aqueous or gas phases are concentrated by absorption into a solid phase. The sampling device consists of a short, thin rod of fused silica (typically 1 cm length and 0.11 mm diameter), coated with an absorbent polymer (SPME fiber), attached to a metal rod (fiber holder), and surrounded (in the standby position) by a protective sheath. This fiber holder is mounted in a modified gas chromatography (GC) syringe (see Figure 2.12 Chapter 2 of this book). 

Membrane extraction (ME) is a solventless extraction method that has gained popularity for the analysis of VOCs in water. In ME the sample is contacted with a membrane surface. Analytes will migrate according to the polymer affinity from the aqueous phase to the surface of the membrane and selectively permeate through it. 

Souza, D. A. and Langas, E. M., Solventless sample preparahon for peshcides analysis in environmental samples by SPME-HRGC/MS, J. Environ. Sci. Health B-Pesticides, Food contaminants, 38, 417-428, 2003. 

Shamsul Hairi, S., Yoshihiro, S., Yoshiaki, K., and Kiyokatsu, J., Solventless sample preparation procedure for organophosphorus pesticides analysis using solid-phase microextraction and online supercritical fluid extraction/high performance liquid chromatography technique. Anal. Chim. Acta, 433, 207-215, 2001. 

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