Gel Permeation Chromatography - Infrared Spectroscopy (GPC-IR)

Gel permeation chromatography (GPC) is a commonly used technique for analyzing the molecular weight distribution of polymers. Infrared spectroscopy (IR) is a well-established technique for analyzing the composition of materials by measuring vibrational absorption bands. Polymers often exhibit relatively simple absorption spectra, which makes them easy to identify by comparison with library data, and are therefore well suited for analysis with IR. The coupling of IR detection to GPC is particularly advantageous because IR detection can be used both as a concentration detector for molecular weight calculations and as a spectroscopic tool for compositional analysis, greatly enhancing the information available from a single GPC experiment. GPC-IR has the advantage to correlate the co-monomer content to a specific molecular weight.

Principle of GPC-IR

• GPC is a powerful analytical technique used to separate dissolved molecules according to size, based on their elution from a column filled with porous gels. Specifically, the samples are separated into their component parts by dissolving them in a mobile phase (solvent) and passing it through a porous column packing.
• The mobile phase from the GPC effluent is converted into aerosol and removed using a pneumatic nozzle. The sample is collected on a Ge disk below the nozzle. After the sample is collected, the disk is transferred to the IR spectrometer where the infrared spectrum of the sample is collected. The spectral data can then be used to generate chromatograms for a comprehensive analysis of the material.

Features of GPC-IR

Alfa Chemistry is a leader in research, engineering, software and services for polyolefin characterization. Our GPC-IR system has the following features:

• Focused on the comprehensive detection of polyolefin.
• Automatic sample preparation.
• Sample care - The dissolution time for each vial can be set individually.
• Comprehensive calculation software.
• Modular design - easy to access to each component.
• Reliability.

Applications of GPC-IR

GPC-IR is the system specifically designed for polyolefin characterization, incorporating many features requested by experienced high-temperature GPC users. Recommended specially for analyzing polyolefin polymers such as high-density polyethylene (HDPE), polypropylene (PP), low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), EP copolymers, EVA, and EBA, etc.

Notes

In GPC-IR detection, it is necessary to choose an eluent that has no obvious absorption in the region of interest, because solvent absorption will also contribute to the spectrum, and the solvent absorption must be subtracted to obtain the spectrum of the sample. Therefore, the quality of the data depends on the solvent, and careful selection is crucial to obtain optimal GPC separation and IR spectroscopic performance^[1].

At Alfa Chemistry, our professional analysts can provide you with improved quality services to support your business. Our GPC-IR platforms ensure consistently accurate and detailed delivery. Alfa Chemistry looks forward to working with you.

Reference

1. Greg D. Saunders, Steve J. O’Donohue, Paul J. DesLauriers. Coupling Fourier Transform Infrared Spectroscopy to Gel Permeation Chromatography via a Liquid Flow Cell. July 1, 2005.

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