Molecular-weight exclusion limit

TABLE 20.2 Molecular Weight Exclusion Limits for TSK-PW Columns"... 

TSK-PW column Pore size (A) Molecular weight exclusion limit... 

A portion of the coal product (168 mg) was dissolved in pure tetrahydrofuran (2 mL) and chromatographed on Styragel GPC columns (Waters Associates). Columns with a molecular weight exclusion limit of 10,000 (2 X 61 cm) and 2,000 (2 X 61 cm) were connected in series. Tetrahydrofuran was used as the mobile phase (0.36 0.01 mL/min). About 30 fractions (3.7 to 3.8 mL) were collected in each experiment. The tetrahydrofuran was removed in vacuo, and a stream of filtered, dry nitrogen was used to remove the final traces of the solvent. The coal product obtained with labeled butyl iodide was partitioned into 17 fractions (total weight, 178 mg). Samples to be used for NMR spectroscopy were dried thoroughly at 25°C at about 5 torr for 40-45 hr to remove the remaining traces of tetrahydrofuran. 

Since the columns are defined in terms of their molecular-weight exclusion limits, it might be necessary to connect as many as eight columns in series to perform a separation. With non-aqueous mobile phases, polystyrenes with... 

Table 1. Reported molecular weight exclusion limits for linear and globular macromolecules on differing pore size SEC supports manufactured by SynChrom Inc. (SynChropak).

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