Fiber extraction procedures

Fiber extraction procedures will depend on the type and portion of plant the fibers are derived from (e.g., bast, leaves, wood) as well as the required fiber performance and economics. Fiber-bearing plants have very different anatomies (e.g., tree versus dicotyledonous plants) and often fibers are derived from agricultural residues or byproducts from industry [8]. Consequentiy, the processing needs can differ greatiy. 

Solid-phase microextraction (SPME) consists of dipping a fiber into an aqueous sample to adsorb the analytes followed by thermal desorption into the carrier stream for GC, or, if the analytes are thermally labile, they can be desorbed into the mobile phase for LC. Examples of commercially available fibers include 100-qm PDMS, 65-qm Carbowax-divinylbenzene (CW-DVB), 75-qm Carboxen-polydimethylsiloxane (CX-PDMS), and 85-qm polyacrylate, the last being more suitable for the determination of triazines. The LCDs can be as low as 0.1 qgL Since the quantity of analyte adsorbed on the fiber is based on equilibrium rather than extraction, procedural recovery cannot be assessed on the basis of percentage extraction. The robustness and sensitivity of the technique were demonstrated in an inter-laboratory validation study for several parent triazines and DEA and DIA. A 65-qm CW-DVB fiber was employed for analyte adsorption followed by desorption into the injection port (split/splitless) of a gas chromatograph. The sample was adjusted to neutral pH, and sodium chloride was added to obtain a concentration of 0.3 g During continuous... 

HSSPME Extraction Procedure. Manual SPME holders were used with a 100- am poly(dimethylsiloxane) (PDMS) and 65- am poly(dimethylsiloxane)-divinylbenzene (PDMS-DVB) fiber assembly (Supelco, Bellefonte, PA). The fibers were conditioned as recommended by the manufacturer. 

Differences are apparent in the second move as well. Both the poster and journal article signal the second move with subheadings, but in the poster, the procedures are presented in bulleted lists of sentences or phrases. Such lists, which could also be numbered, are common in posters. Essential details are presented, specifically those that are needed to understand the rest of the poster. In this case, we chose to highlight a few details about the saponification and extraction procedures. Note, however, that we did not include operating parameters for the GC-electron capture or GC/MS-MS instruments (other than the vendors and model numbers). In a poster, such parameters are optional they may be included, but they are not required. Also, in a poster (but not a journal article), the parameters can be listed in phrases rather than in complete sentences. An illustrative sketch, diagram, or photograph of the SPME holder, fiber, or extraction setup would also be appropriate to include at this point. Finally, if any numerical methods have been used, they should be mentioned in an additional bullet. 

The powdered roots of C. tinctorium were extracted with ethanol (% 96, v/v) using a soxhiet apparatus to remove low molecular weight compounds. Extraction procedures continue until no color could be observed in the ethanol. The residue was extracted with water at 50 °C, 2 hour for two times. Obtained extract was filtered through gauze and Whatman GF/A glass fiber filter and then concentrated at 40 °C in vacuum and dialysed at cut-off 3500 Da to give a 50 °C crude extract. The extracts was kept at-18 °C or lyophilized. 

One particular advantage of this extraction scheme is that large volumes of the sample can be processed on site with no sample manipulation. The sample is pumped through a 0.3 fim Balston microfiber filter tube (glass-fiber filter) directly onto the column array. This scheme fractionates the organic matter present in the water into hydrophobic and hydrophilic acid, base, and neutral fractions. Suspended sediment is also retained, and an extraction procedure for this material is presented. Organic matter from surface water... 

Nicotine contamination in tobacco fiber was assayed by the GLC equipped with an alkaline flame ionization detector. The extraction procedure and GLC conditions have been detailed in a recent paper 6). The sensitivity of detection is below 1 ppm. 

The nitration techniques used in the measurement of the DP of a-cellulose merit further discussion, particularly in relation to the effect of time of nitration on the cellulosic constituents of the fiber. Nitration of lignin results in products soluble either in the nitrating acids or in methanol, and, by a suitable extraction procedure, the lignin component of the fiber can be completely removed. 

The dimensions of cells (length, diameter) are highly variable, dependent on species, maturity, location (position) within the plant, and extraction procedures. Meaningful comparisons can be made only in terms of orders of magnitude. Harris [58] collected the most comprehensive set of data from different sources. Table 8.2 is a composite of these, and other data, for fibers of interest and some for purposes of comparison. From these data, it is quite clear that, on average, the unit cells of ramie, flax, and hemp are longer and coarser than the cotton fiber jute, abaca, and hemp yield the longest fibers, and abaca, henequen, and sisal yield the coarsest fibers. 

Feng Y-D, Tan Z-Q, Liu J-R Development of a static and exhaustive extraction procedure for field passive preconcentration of chlorophenols in environmental waters with hollow fiber-supported liquid membrane. J Sep Sci 2011 34 965-970. 

Recently, LC techniques were introduced for the evaluation of dyestuffs. They have much higher sensitivity than TLC, the choice of conditions, mobile phase, and columns again depends on the chemical properties of the dyes, and an extraction procedure is also required. The results obtained by LC can be used for quantitative data processing and, by comparison of retention times, peak height or area ratios, and trace impurity detection by its higher sensitivity than TLC, more detailed discrimination of fiber samples is possible. Multi-wavelength detection using a PDA detector is also useful, as described above. 

There have been limited amount of research devoted to enzymatic treatment of agro-residual fibers [12,13,58]. When comparing different extraction procedures including water retting, alkalization and enzyme treatment, Yilmaz [13] foimd the strongest and finest corn husk fibers to be produced by a fiber production route of water retting followed by enzyme treatment. 

Pierce the septum of the vial with the SPME needle and press the plunger until the fiber is exposed in the gas phase above the sample (see Rgure 29.1). Secure the plunger in position by turning it clockwise. Perform the extraction procedure for 30 min under stirring condition. 

Since SPME extraction procedure is performed in the headspace mode, verify that the fiber is not dipped into the liquid phase. 

When the extraction procedure is complete, withdraw the fiber into the needle and withdraw the needle from the vial. 

In the dietary fiber extraction flows, there are two key steps. One is enzymolysis extraction and the other is NaOH extraction. So, the two procedures are explored in the following study in this paper. 

The filter-tip pipette, illustrated in Figure 8.9, has two common uses. The first is to remove a small amount of solid, such as dirt or filter paper fibers, from a small volume of liquid (1-2 mL). It can also be helpful when using a Pasteur pipette to transfer a highly volatile liquid, especially during an extraction procedure (see Technique 12, Section 12.5). 

Detection limits reach ca 1 nM when background or capacitive currents are filtered or compensated, in transient methods such as differential pulse polarography (DPP) or voltammetry. Numerous redox molecules, either metabolites or drugs, may be determined in biological samples either directly or after an extraction procedure[3,4]. Particularly miniaturized electrodes using carbon fibers or paste may be implanted and allow the continuous monitoring of some metabolites and drugs in neuronal tissues or arteries[5-8]. 

After extraction in ethanol, the oxygen atom content largely increases to reach about 25% (0/C = 0.30 to 0.38) (Tables 2 and 3), but remains small compared to those of the surface of cellulosic materials. One can therefore conclude that the extraction procedure is not able to remove all the waxes, and maybe other non-cellulosics (pectines or fatty acids) present initially on the surface of cotton fibres. It can be expected nevertheless that the thickness of such a contamination layer is greatly reduced after extraction. One can also mentioned that the cotton fiber C containing the highest initial wax content (0.92%) exhibits the lowest... 

SPME is a solvent-free extraction technique that utilizes short thin solid rod of fused silica coated with absorbent stationery phase. This extraction procedure involves the immersion of the fiber for a certain amount of time while it is being stirred in a water sample from which PAHs are to be extracted. During this period, analytes are sorbed onto the stationary phase of the fiber. Afterwards the fiber is subjected to desorption in the gas chromatography (GC) injector [43]. 

Solid-phase microextraction (SPME) is well documented with respect to its convenience and applicability to sampling volatiles and as an extraction technique to detect ignitable liquid residues when coupled with GCMS (185-188). Nonetheless, fire debris analysts have yet to widely adopt SPME as a viable alternative to the activated charcoal passive headspace technique. SPME is a simple, solventless extraction procedure in which a phase-coated fused-silica fiber is exposed to the headspace above the fire debris packaged in a closed container. A drawback to the procedure requires a rubber sleeve septum be placed at the opening of the container for maximum recovery of analytes. The technique has been applied successfully for the detection of flammable and combustible liquid residues on human skin (189). 

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