Experiences with interlaboratory GPC experiments

Abstract

Based on some round robin experiments organized in the last years by a DIN working group and by the IUPAC working party IV.2.2, the paper discusses measures for getting a better interlaboratory reproducibility of GPC results. The most important points are: ‐ selecting columns according to their separation selectivity and range ‐ avoiding artifacts in the distribution curves, caused by gaps in the pore volume distribution ‐ avoiding adsorption and memory effects ‐ calibration: using calibration standards of high quality selecting suitable calibration points checking the influence of the injected concentration ‐ selecting a common detector ‐ data treatment, especially finding the correct baseline ‐ preparing a detailed data report according to a uniform schedule.

The Impact of Band Broadening on Molar‐Mass Determination of Narrow‐Distribution Polymer by Size‐Exclusion Chromatography

“…Subsequently, the obtained chromatogram is broadened according to Equation (1) and (2). Finally, the chromatogram is retranslated into an MMD by applying the respective calibration for the EMG parameters used in the broadening process.…”

“…Deviations from expected values are frequently ascribed to sidereactions and/or non-ideal polymerization conditions. Several effects such as the correct selection of the baseline [1] and the correct calibration process [2,3] have been proven to be important parameters in SEC and could decisively increase the performance of an analysis if chosen wisely. However, it should be stressed that band broadening (BB), which is a rather complex and indeed non-avoidable instrumental feature of SEC, prevents the precise measurement of molar masses and leads to measured characteristic values that deviate from ideal ones.…”

Viscosimetric detection in size‐exclusion chromatography (SEC/GPC): The Goldwasser method and beyond

“…1. M n is however the least reproducible and least accurate molecular weight quantity that can be determined using SEC ( [26] (http://old.iupac.org/projects/posters01/berek01.pdf), [27]). Accuracy of 15% is the best that can be expected and the deviation observed in Fig.…”

“…This method is applicable to isorefractive polymers or copolymers. Alternative methods to determine M n are also of high interest since M n appears to be the quantity determined in SEC with the lowest accuracy ( [26] (http://old.iupac.org/projects/ posters01/berek01.pdf), [27]). The Goldwasser method has however attracted little attention.…”

Investigation of Chain Dynamics in Poly(n‐alkyl methacrylate)s by Solid‐State NMR: Comparison with Poly(n‐alkyl acrylate)s

“…It is observed that the difference between the apparent and true molar masses is insignificant for PEMA (lower than 2%); it is lower than the experimental error coming from the SEC analysis itself, evaluated at roughly 5 to 10% for M w and 15 to 20% for M n . [29] It should be noted that a difference in tacticity could lead to an additional 20% error in the case of PEMA. [30] In our study, however, the PMMA standards and the investigated PEMA samples had similar syndiotactic contents.…”