Measuring molecular weight distribution of polymer compound by size exclusion mode is one of the typical parts of HPLC and generally called gel permeation chromatography (GPC). Nowadays there is an increasing demand demand for high throughput analysis even in well-established GPC. Here we introduce a novel GPC analysis that affords both high throughput GPC results by overlapped injection using conventional size of columns and simultaneous determination of polymer additives.
Y. Watabe, K. Nakajima, H. Terada
A refractive index detector (RID) that gives a response to a sample weight is commonly employed for GPC to calculate average molecular weight and polydispersity. On the other hand, A UV detector is used for determination of polymer additives such as antioxidants. Consequently, serially connected those two detectors were used for this study. In GPC, there is hardly any eluates prior to exclusion limit. So if the sample elution band from previous injection is managed to be overlapped within this no elution interval in present analysis, short analysis cycle time can be obtained and it provides increased throughput in sequential analyses. When two or more polymer additives are contained, correct determination of those small additives is difficult because complete separation of additives is almost impossible even using GPC columns of small exclusion limit due to small difference of molecular weight among those polymer additives. To address this difficulty, a photodiode array detector (PDA) that affords spectrometric information as well as chromatographic results was employed to give increased separation of polymer additives by peak deconvolution function within a single GPC analysis.
Fig. 1 Chromatogram of Polystyrene and Three Additives (RID)>> Download the full Application Note as PDF
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