Calibration fractionation range

Another important parameter for column selection is the proper choice of sorbent porosity. The pore size of the sorbent determines the fractionation range of the column. The best way of doing this is by looking at the calibration curves of the columns, which are normally documented by the column vendor (cf. Fig. 9.3 for PSS SDV column calibration curves and PSS SDV fractionation ranges) (7). 

The linear column (PSS SDV 5 /mm linear) has a wider molar mass fractionation range while keeping the analysis time roughly the same. Therefore the slope of the calibration curve is much steeper and the resolution will be poorer in this case. The second column with a single pore size (PSS SDV 5 /mm 1000 A) separates only below 50,000 Da, but does this very efficiently in the same time. 

Columns with a narrow pore-size distribution will be characterized by high resolution over a narrow fractionation range, i.e., they exhibit a calibration plot with a shallow slope. Columns with a wide pore-size distribution will be characterized by a wider fractionation range, but poor resolution across that range (i.e., a steep calibration plot). 

Because of the very high molar masses of enzymically polymerized lignin sulfonates, Sephacryl S-300 is used as the gel matrix. The fractionation range is 10 000 to 1 000 000 dalton. Even in this case proteins of known molar mass can be used as calibration standards (Figs. 7 and 8). 

Gao described the use of CPMAS NMR to quantitate binary mixtures of crystalline forms of dela-virdine mesylate, with calculated limits of detection (LODs) of 1-1.5% and observed LODs of 2-3%. Mass fractions ranging from 2%i to 50%i of the minor component were analyzed, and a linear correlation was found between the calculated and NMR-measured values. The methods used here, similar to those described above for neotame, benefit from the fact that no calibration curve or internal standard is needed however. 

Herbert et al. (1994) calibrated probes with a similar method, with the difference that the FCC catalyst particles used flow from a fluidized bed, through an orifice in the center of a porous metal grid, into a square tube (8x8 mm) where they fell 2.5 m into a collection pot. The mass flow rate was determined by particle collection and weighing over a known time period, and the volume fraction range calibrated was only O.Olto 0.1. 

Name Type Chemical nature Eluant (mobile phase) Maximum exclusion limit Calibration Number of fractionation ranges Bead size (pm) Notes... 

The principles causing retention behaviour, separation variables, molecular weight calibration and associated terminology such as interparticle and intraparticle volume, selective permeation, fractionation range and molecular hydrodynamic radius are as for open column size exclusion (Chapter 4). 

The theoretical relationships between the physical structure of a porous SEC packing (i.e. its particle shape, particle diameter, pore size distribution, cp) and the width of the fractionation range as well as the linearity of the SEC calibration curve... 

Chromatorapf c methods For gel filtration of polysaccharide fraction PI, a Sephacryl S-300 chromatographyc column (1,1 X 46,7 cm) was calibrated with standard dextrans (molecular mass range 266, 72, 40, and 17 KDa Sigma Chemicals), and the void volume determined with blue dextran. Polysaccharide sample (0.5 mL 2 mg/mL) was applied and eluted with 50 mM NaOH, fractions 1 mL being collected and carbohydrate absorbance (phenol-H2S04) being monitored. 

Chromatograms of the ethanol-soluble fraction were obtained in THF on Toyo Soda Oligomer columns over a range of sample masses, as shown in Figure 5 The exclusion limit of these columns is 50,000 and Mp" values above 10,000 are inaccurate because the calibration curve is very steep in this region. Consequently, chromatograms were also obtained on the "Main Column" GPC with the results shown in Figure 6. 

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