High Performance Size Exclusion Chromatography. VI. Evaluation of the Weight Coordinate

摘要

A series of high performance size exclusion chromatography (HPSEC) runs was made, using polystyrene standards, for the purpose of evaluating the applicability of the weight coordinate. Use of this coordinate was found to be considerably more precise than use of the time coordinate and was equivalent in precision to use of the time coordinate in conjunction with the application of an internal standard. The method consisted of continually measuring the weight of the mobile phase emerging from the columns with the Sartorius electronic balance and transmitting the voltage output of the balance to a Wang microcomputer for processing and display on a Selectric typewriter. Application of the weight coordinate obviated the use of the internal standard and permitted the shortening of run time by about one third. Experiments were performed with standards of four different molecular weights and were conducted at temperatures of 35, 45, and 55 C. The variation in temperature provided information about the temperature coefficient of HPSEC as a function of polystyrene molecular weight in the prevailing solvent. The retention weight and temperature coefficient for the internal standard, methylene chloride, was unusually large and it was hypothesized that this substance is absorbed by the polystyrene gel of the columns. (ERA citation 06:012602)