Temperature solid-phase microextraction

Fhllman, A. Rittfeldt, L., Detection of chemical warfare agents in water by high temperature solid phase microextraction-ion mobility spectrometry (HTSPME-IMS), Int. J. Ion Mobil. Spectrom. 2001, 4, 85-87. 

Solid-phase microextraction eliminates many of the drawbacks of other sample preparation techniques, such as headspace, purge and trap, LLE, SPE, or simultaneous distillation/extraction techniques, including excessive preparation time or extravagant use of high-purity organic solvents. SPME ranks amongst other solvent-free sample preparation methods, notably SBSE (Section 3.5.3) and PT (Section 4.2.2) which essentially operate at room temperature, and DHS (Section 4.2.2),... 

Here is a student procedure to measure nicotine in urine. A 1.00-mL sample of biological fluid was placed in a 12-mL vial containing 0.7 g Na2CO , powder. After 5.00 pig of the internal standard 5-aminoquinoline were injected, the vial was capped with a Teflon-coated silicone rubber septum. The vial was heated to 80°C for 20 min and then a solid-phase microextraction needle was passed through the septum and left in the headspace for 5.00 min. The fiber was retracted and inserted into a gas chromatograph. Volatile substances were desorbed from the fiber at 250°C for 9.5 min in the injection port while the column was at 60°C. The column temperature was then raised to 260°C at 25°C/min and eluate was monitored by electron ionization mass spectrometry with selected ion monitoring at m/z 84 for nicotine and m/z 144 for internal standard. Calibration data from replicate... 

Wennrich et al. [97] have described a method for the determination of nine chlorophenols in soil using accelerated solvent extraction with water as the solvent combined with solid-phase microextraction and gas chromatography - mass spectrometry. An extraction temperature of 125 °C and ten-minute extractions were optimal. 

Wennrich [167] optimised important accelerated solvent extraction parameters, such as extraction temperature and time, using a spiked wetland soil. The effect of small amounts of organic modifiers on the extraction yields was studied. An extraction temperature of 125 °C and ten-minute extractions performed three times proved optimal. Two accelerated solvent extraction-solid-phase microextraction procedures without and with an organic modifier (5% acetonitrile) were evaluated with respect to precision and detection limits. 

The following table provides data on the common salts used for salting out in chromatographic headspace analysis, as applied to direct injection methods and to solid phase microextraction.1 2 Data are provided for the most commonly available salts, although others are possible. Sodium citrate, for example, occurs as the dihydrate and the pentahydrate. The pentahydrate is not as stable as the dihydrate, however, and dries out on exposure to air, forming cakes. Potassium carbonate occurs as the dihydrate, trihydrate, and sesquihydrate however, data are provided only for the anhydrous material. The solubility is provided as the number of grams that can dissolve in 100 ml of water at the indicated temperature. The vapor enhancement cited is the degree of increase of the concentration of vapor over the solution of a 2% (mass/mass) ethanol solution in water at 60°C.3... 

Figure 1.19 Mass spectra of acetaldehyde PFB-oxime (a), diacetyl mono PFB-oxime (b), acetoin PFB-oxime derivative (c), and o-chlorobenzaldehyde PFB-oxime (d) recorded in the GC/MS analysis of standard solution performed in positive ion chemical ionization mode using methane as reagent gas (reagent gas flow 1 mL/min ion source temperature 200 °C). Flamini et al., (2005) Monitoring of the principal carbonyl compounds involved in malolactic fermentation of wine by synthesis of 0-(2,3,4,5,6-pentafluorobenzyl) hydroxylamine derivatives and solid-phase-microextraction positive-ion-chemical-ionization mass spectrometry analysis, Journal of Mass Spectrometry, 40, p. 1561. Copyright John Wiley Sons, Ltd. Reproduced with permission...

Figure 5.12 Temperature effect in the HS-SPME adsorption of the wine CFSV on DVB/CAR/PDMS fiber. (Reprinted from Rapid Communications in Mass Spectrometry 21, Fedrizzi et al., Concurrent quantification of light and heavy sulphur volatiles in wine by headspace solid-phase microextraction coupled with gas chro-matography/mass spectrometry, p. 711, Copyright 2007, with permission from John Wiley Sons, Ltd)...

Solid phase microextraction (SPME) was used to determine the presence of volatiles in cranberry seed extract. The optimized SF extract was diluted with 5mL of a mixture of dichloromethane and methanol (1 1). A carbowax/divinylbenzene (CW/DVB) fiber was exposed for 60 min to the headspace of the diluted cranberry seed extract. The assembly was kept at 30 C with stirring. The fiber was then desorbed for 5 min in the injection port of an HP 6890 Series GC interfrced with a HP 5973 Series MSD. The injector temperature was maintained at 220 C. The helium flow was kept at 2mL/min. The oven temperature was initially maintained at 40°C for 3 min and then ramped at 4°C/min to 100 C and finally heated to 220°C at 15°C/min. 

Approximately 0.5 g of grounded rosemary was weighed into a 20-mL glass vial as a single san le for hot water extraction at 100 °C. Approximately 8 mL of distilled water was added into the rosemary vial. The loaded vial was put on a hot plate to perform the hot water extractioa The vial was loosely sealed with a rubber cap. The water extraction time was IS min. After the hot water extraction at 100 °C, the glass vial was removed from the hot plate and cooled down to room temperature. Clear aqueous solution was obtained by filtration using small filter paper. This water sanple was then ready for solid-phase microextraction. 

Gas chromatography is not commonly used for the determination of arsenic compounds. The reason for this is that not all arsenic compounds are easily volatilized. A rapid method for the determination of arsine, methylarsine, dimethylar-sine, and trimethylarsine in air based on gas chromatography-mass spectrometry (GC-MS) was recently published (65). In another smdy, DMA and MA present in urine were derivatized with thioglycol methylate and extracted with a 100 qm solid-phase microextraction fiber in 40 minutes. Thereafter, the two arsenic compounds were determined with GC-MS (66). The combination of purge and trap gas chromatography with atomic fluorescence spectrometry was used for the determination of arsenous acid, arsenic acid, MA, and DMA in a mushroom sample (67). Low-temperature gas chromatography coupled to ICP-MS was used to determine the volatile arsenic compounds in intraoral air (68). This method is also applicable to the determination of volatile arsenic compounds in landtill gases. 

The low concentration levels of the compounds in environmental samples impose specific requirements in terms of sample injection for GC analysis. In addition to the common injection techniques of capillary GC (split, splitless, on-column, and programmed temperature vaporized (PTV) injection), some other sample introduction methods coupled to GC such as solid-phase microextraction (SPME), headspace, etc., have favored the versatility of GC and reduced the time required for sample preparation. These techniques have an advantage over the conventional injection methods, which is that a preconcentration step prior to GC... 

Accelerated solvent extraction (ASE), focused microwave soxhiet extraction (FMSE), immuno affinity cleanup (im-Cu), liquid-liquid extraction (LLE), low-temperature lipid precipitation (LTLP), matrix solid-phase dispersion (MSPD), microwave-assisted extraction (MAE), nanofiltration (NF), pressurized fluid extraction (PEE), single drop microextraction (SOME), solid-phase extraction (SPE), solid-phase microextraction (SPME), steam distillation (SD), stir bar sorptive extraction (SBSE), surpercritical fluid extraction (SFE), subcritical fluid extraction (ScFE), supported liquid membrane extraction (SLME), ultra-sonication (US), size exclusion chromatography (SEC), liquid chromatography-fraction collection (LC)... 

In headspace analysis, the plastic is placed in a vial (at a raised temperature) and the volatiles formed are stripped by a flow of carrier gas. The stripped volatiles are trapped in a suitable sorbent (e.g., using a solid-phase microextraction device) and subsequently thermally desorbed into a gas chromatograph. Process gas chromatographs are used in industrial analysis of volatiles in plastics. An example of this technique is the determination of residual vinyl chloride monomer in plastics in the range of 5-50 g per kg. With direct injection of a polymer solution, there is a danger of side-effects (a loss of reactive monomers due to polymerization in the injection port or an increase in its content due to depolymerization at a high injection temperature). 

While open tubular (OT) columns are the most popular type, both open tubular and packed columns are treated throughout, and their advantages, disadvantages, and applications are contrasted. In addition, special chapters are devoted to each type of column. Chapter 2 introduces the basic instrumentation and Chapter 7 elaborates on detectors. Other chapters cover stationary phases (Chapter 4), qualitative and quantitative analysis (Chapter 8), programmed temperature (Chapter 9), and troubleshooting (Chapter 11). Chapter 10 briefly covers the important special topics of GC-MS, derivatization, chiral analysis, headspace sampling, and solid phase microextraction (SPME) for GC analysis. 

Solid-phase microextraction (SPME) was introduced in the early 1990s by Arthur and Pawliszyn. SPME is a simple solvent-free sample preparation method for GC and LC. The extraction is based on the partitioning of the analyte between the organic phase on the fused silica fiber and the matrix. Many factors such as pH, temperature, salt concentration, and stirring affect the equilibrium constant and the equihbration time. Fiber lifetime is a significant issue. SPME fiber is quite sensitive to complex matrix such as... 

The solid-phase microextraction fiber was introduced into the port of a gas chromatograph held at 280 C for 4 min to desorb derivatized analytes from the fiber onto a chromatography column held at 80°C. Analytes have negligible vapor pressure at 80 C, so they remain at the start of the column until the column temperature is raised. 

Rubiolo, P., F. Belliardo, C. Cordero, E. Liberto, B. Sgorbini, and C. Bicchi. 2006. Headspace solid phase microextraction fast GC in combination with principal component analysis as a tool to classify different chemotypes of chamomile ower-heads (Matricaria recutita L.). Phvtochem. Anal.. 17 217. Proot, M. and P. Sandra, 1986. Resolution of triglycerides in capillary SFC as a function of column temperature. J. HiehRes. Chromatoer. Chromatoer. Commun.. 9 618. 

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