Dextran standards

FIGURE 5.1 Analysis of American Polymer Standards dextran standards, two columns AMGEL Linear 300 X 7.8 mm, eluant DMSO, flow rate I ml/min, temperature S0°C, detector (DRI). 

The selective separation range of P-6/S-200 was determined with Blue Dextran (Vexdi exclusion limit) and fructose (V,o total permeation limit). Molecular weight (degree of polymerization) calibration (Fig. 16.22) was established with dextran standards and low dp pullulans (dp 3, 6, 9, 12, 15, 18) formed by the controlled hydrolysis of high dp pullulan. 

At end, it is important to mention that calcium pectate gel beads were compared with calcium alginates gel beads for all entrapment uses [65, 66] in this work, the authors determined the pore size of the beads by size exclusion chromatography using dextran standards and other solutes. 

The blend of T-70 and T-40 dextran materials was utilized as a polydisperse calibration standard for the linear calibration method and the T-40 dextran standard was used as a sample for evaluation. Concentrations of 0.15% W/V were injected for each dextran material chromatographed. 

Dextran polymers were used to evaluate the utility of the linear, polydisperse calibration method for water-soluble polymer characterization. A blend of T-40 and T-70 dextran standards was used as a polydisperse calibration standard. Table VIII displays the report from the linear calibration method using this standard. Nine Iterations of the search algorithm were required for convergence to the true and Mn values of the standard. As can be seen in the report, the elution volume profile of the standard contained 72 area/time slices upon which calibration calculations were based. The slice width was set at 10 seconds/siIce. Figure 5 shows a plot of the calibration curve generated from the linear calibration method utilizing the dextran standard,... 

Table VIII. Calibration Report For Polydisperse Dextran Standard...

Figure 5 Calibration curve for polydisperse dextran standard using a linear method. Plot of log (MW) vs. elution volume. Horizontally, each - represents 0.U8 units.

Labeled dextrans for calibration purposes were prepared by dissolving (in 15 mL of 100 mM Na2CQ3) five dextran standards (100 mg each) of the following average molecular weight distributions 10,000 40,000 70,000 500,000 and 2,000,000. After stirring overnight, unreacted label was removed by exhaustive dialysis of the solution with water. The solution was freeze-dried, and the modified yellow dextrans were reclaimed. 

It had a degree of esterification of 73 and was labeled 73G. Characterization and preparation of samples were as reported previously (5) with minor modification. Samples to be neutralized with NaOH were dissolved in 0.01 M phosphate buffer (pH 6.1) containing 0.1 M EDTA, titrated to pH 7 with 0.1 M NaOH, dialysed against four changes of water over 48 hr., centrifuged for 1 hr. at 30,000 x g to remove insoluble matter and then lyophilized. Protonated samples were dissolved in deionized water (Continental Water Systems) followed by dialysis, centrifugation, and lyophillization weight cut off of 12,000. Dextran standards were from Pharmacia... 

All chemicals used were of analytical grade from Ajax Chemicals. IM HCl, NaOH, and NaCl solutions were used for pH and ionic strength adjustments. For some experiments, KCl or CaCl 2 were used as the electrolyte. This is indicated in the relevant results section. Dextran standard (MW 1000 Da), which was used for NF pore size comparison, was purchased from Fluka, Australia. 

Figure 3, Elution profile of water-soluble material from microwave oven treated (200°C for 2 min) milled spruce chips after SEC using Superdex 75 and 200 columns, Rl-detection (solid line) and absorbance at 280 nm (hatched line) is shown (AU Absorbance units). The applied sample volume was 100 pd. The arrows mark the elution volumes from fractions of AcGGM analyzed with MALDI-MS (Mp 8500, 3900 and 1700). Monomeric sugars eluted at 39-40 ml. The elution volumes using dextran standards of molecular weights 70 000,...

Summary of the size-determination of the purified AcGGM using SEC with dextran standard molecules (SEC-D) and AcGGM standard molecules (SEC-G) and using NMR spectroscopy. )These number-average DPs are equivalent to approx, calculated molecular weights of 3500 (Fraction 8) and 1900 (fraction 9). Data from reference 2 (SEC-D and NMR) and reference 3 (SEC-G). 

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