Polyethylene oxide , calibrant

FIGURE 4.2 Polyethylene oxide, dextran, and protein calibration curves for TSK-GEL SW Columns. Column TSK-GEL SW, two 7.S mm x 60 cm columns in series. Sample , proteins Q, polyethylene oxides O, dextrans. Elution dextrans and polyethylene oxides distilled water proteins 0.3 A1 NaCI in 0.1 M phosphate buffer, ph 7. Flow rate 1.0 ml/min. Detection UV at 220 nm and Rl. 

Figure 6.21 shows the calibration curves of the SB-800 HQ series using standard pullulan. Because a high molecular weight standard sample is not available, the calibration curves of 805 and 806 are partly estimates (dotted lines). The difference in the conformation between polyethylene oxide (PEO) and pullulan in the solvent causes a shift of the calibration curves of pullulan slightly higher than those of PEO. The OHpak SB-800HQ series is better suited for the analysis of hydrophilic samples than the Asahipak GS/GE series. 

Calibration curves for the Ultrahydrogel column family using using polyethylene oxide standards and water as the mobile phase are shown in Fig. 11.12. 

FIGURE 12.7 SEC calibration curves for PL aquagel-OH columns (300 X 7.5 mm), eluent water at 1.0 ml/min, polyethylene oxide/glycol calibrants. 

On addition of polyethylene oxide of M.W. 300,000 at a concentration of 0.025 g liter , it is seen that a single calibration curve is obtained, independent of NaCl concentration. (It should be noted, however, that at very low NaCl concentration, less than about 0.005 M, the curve still appears at lower elution voliames). This curve is not linear but does exhibit fairly good resolution. It is likely that the effect of polyethylene oxide... 

The effect of pH in the range studied is completely eliminated by addition of 300,000 MW polyethylene oxide with "collapse" of the data onto a single calibration curve. This competitive adsorption effect will be discussed more fully in section 4. 

In the presence of polyethylene oxide MW 300,000 at a concentration of 0.025 g liter , variations in pH and ionic strength have no effect on elution volumes and a single calibration curve is obtained as shown in Figure 4 and Table II. This behavior presumably also results from modification of the glass surface by the polyethylene oxide surfactant, but in this case charge effects appear to be completely suppressed and the effective pore diameter and volume reduced. Such an interpretation is also in accord with the fact that the elution voliomes are lower with polyethylene oxide than with Tergitol, since Tergitol is a much smaller molecule than the polyethylene oxide. 

Figure 4, Molecular weight calibration curves for nonionic polyacrylamide for a single column (4 ft X in. i.d.) containing 2000 A CPG-IO (120/200 mesh) packing for a number of mobile phases containing either polyethylene oxide (Mxv...

Figures 6, 7 and 9 show calibration curves using two multi-column combinations and illustrate the degree of "optimization obtained in this system. The mobile phases for Figures 6 and 7 contained 0.025 g polyethylene oxide and ion exclusion and adsorption effects should therefore be largely eliminated. Figure 6 shows that reasonably good resolution can be obtained with a combination of five columns but does exhibit some loss of peak separation at the low cuid high MW ends. In Figure 7 the effect of adding a sixth column of small pore size is illustrated and it is seen that resolution at the low MW end is thereby somewhat improved. This calibration curve is effectively linear with a change of slope at 500,000 MW. It should provide a useful aqueous GPC system for MW and MWD determination of nonionic polyacrylamides.

Mass spectrometry. (+)Fast atom bombardment (FAB) mass spectrometry was carried out with a JEOL JMS-SX/SX102A mass spectrometer. Dried samples were dissolved in methanol-water, mixed with (thio-) glycerol, and applied to a direct insertion probe. During the high resolution FAB-MS measurements, a resolving power of 10,000 (10% valley definition) was used. Cesium iodide, glycerol, or polyethylene oxide (MWav = 600) was used to calibrate the mass spectrometer. 

Aqueous SEC Experiments. Aqueous SEC separations were carried out at ambient temperature using two column sets of MicroPak TSK PW Type gel which were investigated for linearity of molecular weight calibration curve using polyethylene glycol (PEG) and polyethylene oxide (PEO) narrow MWD standards. Columns were matched in pore volume as closely as possible to promote linearity of the molecular weight calibration cuiA e. Column set A consisted... 

Table VII. Comparison of Calibration Reports Using A Series of Narrow MWD Polyethylene Oxide Standards for MicroPak TS C PW Column Sets...

Figure i A. Calibration curves using a series of narrow MWD polyethylene oxide standards for MicroPak TSK PW column sets. Linear least squares fit for log (MW) vs. elution volume. Column set A MicroPak TSK 3000PW + LOOOPW + 5000PW + 6000PW. 

Polyethers. Polyethers such as polyethylene oxide (PEO) and polypropylene oxide (PPO) have been used for ESI-MS calibration [10,11,19]. The predominant ions for these calibrants are cation attachments, and sodium attachment is frequently observed, due to traces of sodium in solvents and glassware. The positive-ion ESI mass spectra of PEO and PPO are characterized by abundant [M + nNa]n+ and some [M + ] + species. Macrocyclic polyethers and crown ethers were also used as ESI-MS calibrants [11]. In general, nonderivatized polyethers show the following drawbacks when used as calibrations solutions (1) they are difficult to flush out of the ion source, (2) they generate complex mass spectra resulting from the presence of several different cation sources, and... 

To overcome the difficulties of ESI-MS, Simonsick and Prokai added sodium cations to the mobile phase to facilitate ionization [165,166]. To simplify the resulting ESI spectra, the number of components entering the ion source was reduced. Combining SEC with electrospray detection, the elution curves of polyethylene oxides) were calibrated. The chemical composition distribution of acrylic macromonomers was profiled across the molar mass distribution. The analysis of poly(ethylene oxides) by SEC-ESI-MS with respect to chemical composition and oligomer distribution was discussed by Simonsick [167]. In a similar approach aliphatic polyesters [168], phenolic resins [169], methyl methacrylate macromonomers [169] and polysulfides have been analyzed [170]. The detectable mass range for different species, however, was well below 5000 g/mol, indicating that the technique is not really suited for polymer analysis. 

Benzyl alcohol has been tested at 100°C on silica columns. To prevent potential solute interactions with silica stationary phase, it is recommended to prefer cross-linked PS columns with benzyl alcohol at 130°C and polytetrahydrofurans as calibration standards (polystyrene and polyethylene oxide standards interact with the stationary phase under the analytical conditions) [5]. 

SEC calibration using polyethylene oxide (PEO) and polysaccharide (PSAC) standards, eolumn PL aquagel-OH 50 300 x 7.5 mm, eluant water, flow rate 1 ml/minute, detector RI. 

Universal calibration plot for polyethylene glycol, polyethylene oxide, polysaccharide, and polyacrylamide in 0.10 M sodium nitrate at 35 C. 

Most VP-based copolymers are also characterized by K value. However, the literature on molecular weights of VP copolymers is very sparse. Wu and Senak reported in 1990 (6) the absolute molecular weights of cationic copolymers of quatemized vinyl pyrrolidone and dimethylaminoethyl methacrylate by size exclusion chromatography with low-angle laser light scattering (SEC/LALLS) and SEC with universal calibration (see Table 8). The molecular weights (relative to polyethylene oxide standards) of nonionic copolymers of vinyl pyrrolidone and vinyl acetate, a nonionic terpolymer of vinyl pyrrolidone, dimethylaminoethyl methacrylate, and vinyl caprolactam, and anionic copolymers of vinyl pyrrolidone and acrylic acid were also reported in 1991 (7) by Wu et al. (see Tables 6 and 7). 

Belenkii et al. reported in 1975 (8) the SEC of PVP with unspecified molecular weight using Pharmacia Sephadex G-75 and G-lOO columns and a 0.3% sodium chloride solution as the mobile phase. Deviations from universal calibration behavior were noticed from PVP, dextran, polyethylene oxide (PEG), and polyvinyl alcohol. With the development of the important semirigid polymer gel, Toyo Soda TSK-PW columns for water-soluble polymers, Hashimoto et al. reported in 1978 (9) the SEC of PVP K-30 and K-90 using TSK-PW 3000 and two 5000 columns an 0.08 M Tris-HCl buffer (pH =... 

Polar polymers require careful observation of their elution behaviour before the application of the hydrodynamic volume concept. Polyacrylonitrile (PAN) in a dimethylformamide (DMF)/lithium bromide (LiBr) solution at 60°C showed different elution behaviour to that of polyethylene oxide (PEO) and polyvinyl pyrrolidone, which means that for PAN the universal calibration method cannot be applied with PEO as standards [22]. On the other hand, copolymers of acrylonitrile and vinyl ether could be measured in a DMF/LiBr solution at 55°C [23]. Thus these SEC conditions were suitable for these copolymers using the universal calibration method. The Mark-Houwink equations were as follows ... 

By calibrating the column or column set with a set of standards, a calibration curve of retention versus the logarithm of molar mass is constructed so that molar mass averages may be calculated for unknown polymers. Figure 6.10 is an example chromatogram of a separation of a polyDADMAC coagulant polyelectrolyte. The molar mass distribution, see Figure 6.11, is relative to the calibration standards used, polyethylene oxide in this example. 

Fig. 1.5 Deviation of the molar mass values for hypetbranched poly (etheramide) determined by different SEC-interpretation methods square) SEC-RI detection tmd polyethylene oxide standard (cycle) SEC-RI detection and polystyrene standard (triangle) of-line SEC-viscosity detection and universal calibration (inverted triangle) SEC-MALLS (static light-scattering detection) [62]...

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