Polyethylene glycols , calibrant

The range of pore sizes in which TSK-GEL PW and TSK-GEL PWxi columns are available permits a wide spectrum of water-soluble substances to be analyzed. Calibration curves for polyethylene glycols chromatographed on... 

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. 

IR analysis can also be used quantitatively to determine the EO-PO ratio [12]. Using mixtures of polyethylene glycol and polypropyene glycol as calibration standards, the ratio of two absorbances, one due to the methyl group of the PO unit (e.g., the C-H stretch band at 2975 cm ) and one due to the methylene group (e.g., the C-H stretch band at 2870 cm ), are plotted against percent of PO content. The ratio of the same two absorbances taken from the IR spectrum of a poloxamer may then be used to determine its percent of PO content by interpolation. 

The side-by-side diffusion cell has also been calibrated for drug delivery mass transport studies using polymeric membranes [12], The mass transport coefficient, D/h, was evaluated with diffusion data for benzoic acid in aqueous solutions of polyethylene glycol 400 at 37°C. By varying the polyethylene glycol 400 content incrementally from 0 to 40%, the kinematic viscosity of the diffusion medium, saturation solubility for benzoic acid, and diffusivity of benzoic acid could be varied. The resulting mass transport coefficients, D/h, were correlated with the Sherwood number (Sh), Reynolds number (Re), and Schmidt number (Sc) according to the relationships... 

Figure 4.20 Calibration curves for size-exclusion liquid chromatography. Column, TSK GEL G3000SW, 120 cm x 7.5 mm i.d. eluent, 0.2 m sodium phosphate buffer pH 6.8 flow rate, 1.0 ml min-1. Standards 1, protein-, 2, dextran, and 3, polyethylene glycol.

MALDI is the method of choice for the analysis of synthetic polymers because it usually provides solely intact and singly charged [62] quasimolecular ions over an essentially unlimited mass range. [22,23] While polar polymers such as poly(methylmethacrylate) (PMMA), [83,120] polyethylene glycol (PEG), [120,121] and others [79,122,123] readily form [M+H] or [M+alkali] ions, nonpolar polymers like polystyrene (PS) [99,100,105,106] or non-functionalized polymers like polyethylene (PE) [102,103] can only be cationized by transition metal ions in their l-t oxidation state. [99,100] The formation of evenly spaced oligomer ion series can also be employed to establish an internal mass calibration of a spectrum. [122]... 

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... 

Although these peak areas were sufficient to quantify quinaldic acid on Carbowax columns, residual water present in the extracts of the ion-exchange resins interfered in previous experiments using water-sensitive polydimethylsiloxane stationary phases. The change to a polyethylene glycol stationary phase eliminated the water interferences, and good linear calibration curves for methyl quinaldate were then obtained. 

The critical diagram M vs retention time for a short RP-18 column of 60 mm length is shown in Fig. 7A. At acetonitrile concentrations > 47 vol.% in the solvent mixture, the retention time decreases as the molar mass of the PEO calibration sample increases retention corresponds to a size-exclusion mode. The reverse behaviour, i.e. the adsorption mode, is obtained at acetonitrile concentrations < 45 vol.%. The critical point of adsorption is operating at an eluent composition of acetonitrile-water 46 54 v/v, where separation is accomplished exclusively with respect to the functional endgroups- (see Fig. 7B). For the alkoxy-terminated PEOs, two distinctively different fractions are obtained, due to the formation of polyethylene glycol as an unwanted by-product. In the case... 

Calibration curves for proteins (elosed circles), polyethylene glycols (open circles), and dextrans (half-closed circles). Columns, TSKgel SW, 10 pm, 60 em x 7.5 mm, two in series. (A) G2000SW, (B) G3000SW, (C) G4000SW. Mobile phase, proteins 0.1 M phosphate, pH 7, + 0.3 M sodium chloride dextrans and polyethylene glycols distilled water flow rate, 1.0 ml/minute detection, 220 nm, UV. 

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

Figure 7.5 Molecular mass calibration curve of TSKgel GMPW (a 600 x 7.5 mm I.D. colunrn) for polyethylene glycol in distilled water [15].

Add aliquot masses between 50 and 500 mg of the mixture to between 10 and 50 ml of polyethylene glycol 00 (PEG 00) (multi-component calibration solution). 

UV-Vis is the most commonly used detection method in HPSEC characterization. However, DOM/HM moieties possess no maximum absorption at any wavelength in the UV-Vis spectrum. As a consequence, numerous wavelengths have been used for detection. In order to standardize SEC procedures for enhanced reproducibihty of results, Zhou et al. [44] conducted a study to determine optimum wavelengths. The results showed reasonable detection of DOM/HM between 230 and 280 ran. For very dilute samples like clean waters with low carbon contents, which require additional sensitivity, 230 ran was preferred however, 254 ran was recommended for water samples rich in HM-type moieties, as is often the case for freshwaters. The calibration of the SEC system causes its own error because there are no available standards with hydrod)mamic and chemical properties comparable to those of studied DOM/HM solutes. Several commercial compoimds have been apphed for the SEC calibration such as polyst3nene sulfonates (PSS), polyethylene glycols (PEGs), globular proteins, several miscellaneous compounds... 

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