GPC Analysis FAQ: Your Complete Guide to Gel Permeation Chromatography for Polymer Characterization

GPC analysis, or Gel Permeation Chromatography, is a chromatographic technique used to determine the molecular weight distribution of polymers. It separates polymer molecules based on their size in solution by passing them through a porous column matrix. Larger molecules elute first because they cannot penetrate the pores, while smaller ones take longer paths through the pores and elute later.
GPC analysis is crucial for polymer characterization, helping chemists understand properties like Mn (number average molecular weight), Mw (weight average molecular weight), and polydispersity index (PDI).
Explore our GPC Analysis Service for expert support in polymer profiling.

The cost of a GPC system varies based on its configuration, detectors, and brand. On average:
Basic GPC setup (single detector): $50,000–$80,000 USD
Advanced GPC with multi-detectors (e.g., RI, UV, MALS, viscometer): $100,000–$200,000+ USD
Custom modules or autosamplers can add $10,000–$50,000 more
Due to high capital costs and expertise needed, many companies prefer outsourcing to a specialized lab like ResolveMass Laboratories, which offers GPC analysis as a service with fast turnaround and validated protocols.

GPC test stands for Gel Permeation Chromatography test. It’s used to evaluate molecular weight distribution, polymer purity, and chain length variations in a polymer sample. The term is sometimes used interchangeably with SEC (Size Exclusion Chromatography), especially when discussing aqueous polymer systems.
At ResolveMass, GPC testing is used extensively in biopolymer, synthetic polymer, and drug delivery polymer research.

Though both are liquid chromatography techniques, GPC and HPLC differ in their separation mechanisms and applications:
Feature
GPC (Gel Permeation Chromatography)
HPLC (High-Performance Liquid Chromatography)
Basis of Separation
Molecular size (hydrodynamic volume)
Polarity, charge, hydrophobicity, or affinity
Analyte Type
Polymers, proteins, large molecules
Small molecules, drugs, metabolites, peptides
Columns Used
Porous polymer or silica-based columns
C18, ion-exchange, normal-phase columns
Detection Focus
Molecular weight distribution
Retention time, quantification, purity
GPC is a subset of HPLC focused specifically on size-based separations, whereas HPLC encompasses a broader array of separation strategies.

Gel Permeation Chromatography (GPC) works by separating molecules based on their size in solution. The sample is injected into a column packed with a porous material (usually silica or polymer). The larger molecules are unable to enter the pores, so they pass through the column more quickly. In contrast, smaller molecules can enter the pores and take longer to elute, separating based on their hydrodynamic volume. The elution profile generated by GPC helps identify molecular weight distribution in polymers, which is essential for understanding their properties.
Learn more about our GPC Analysis Services.

GPC, or Gel Permeation Chromatography, is a powerful analytical technique used to determine the molecular weight distribution and polydispersity index (PDI) of polymers. It is a form of size exclusion chromatography (SEC) and plays a pivotal role in polymer characterization, providing crucial information about the molecular size and structure, which influences the polymer’s mechanical, chemical, and thermal properties.

The principle of GPC relies on the separation of molecules based on size rather than their chemical properties. The larger molecules travel through the column faster, as they cannot enter the small pores of the stationary phase. Smaller molecules, on the other hand, are able to enter the pores and take a longer, more convoluted path, resulting in slower elution. By analyzing the time it takes for different-sized molecules to elute, GPC provides valuable data on the molecular weight distribution of the sample.

Gel Permeation Chromatography (GPC) is a technique used to measure the molecular weight and size distribution of polymers. During GPC, a polymer sample is passed through a column packed with porous material. As the sample flows through, the larger molecules are excluded from the pores and elute first, while smaller molecules are retained longer, entering the pores and diffusing in and out, causing delayed elution. This separation allows for the calculation of molecular weight averages and the polydispersity index (PDI), which are essential for polymer characterization.

GPC provides critical insights into the molecular weight distribution of a polymer sample. Specifically, it helps determine:
Number average molecular weight (Mn)
Weight average molecular weight (Mw)
Polydispersity Index (PDI), which measures the spread of molecular weights within the sample
These parameters are crucial for understanding the polymer’s physical properties, such as viscosity, strength, and thermal stability.

GPC is used primarily for polymer characterization, allowing scientists to determine the size distribution, molecular weight, and polydispersity of polymer samples. These data are crucial for predicting the material’s properties and performance in various applications, from industrial polymers to biomedical devices. Additionally, GPC can also be used for:
Quality control in polymer manufacturing
Polymer degradation studies
Characterizing copolymers and their distribution

To analyze GPC data, the following steps are typically followed:
Sample Preparation: Dissolve the polymer sample in a suitable solvent to ensure uniformity.
Column Calibration: Calibrate the GPC system using known standards (polystyrene or other polymer standards) for accurate molecular weight determination.
Data Collection: Inject the sample into the GPC column, where the separation occurs based on molecular size.
Detection and Calculation: The elution time is recorded, and detectors (like refractive index or light scattering) are used to measure the concentration of molecules eluting from the column.
Analysis: Use software to analyze the chromatogram, determine the molecular weight averages (Mn, Mw), and calculate the polydispersity index (PDI).

A common example of GPC use is in polymer synthesis. For example, a chemist might use GPC to determine the molecular weight distribution of polyethylene produced in a polymerization reaction. The resulting GPC analysis can reveal whether the polymer’s molecular weight is within the desired range for specific applications, such as plastics, films, or coatings.

GPC accuracy depends on several factors:
Column calibration: The accuracy of GPC is influenced by the use of appropriate calibration standards, such as polystyrene standards, which may vary from sample to sample.

If you want explore detail information on GPC calibration standard, you can read this article: Understanding GPC Calibration Standards: A Guide to Accurate Molecular Weight Analysis

Detector type: Refractive index (RI) detectors offer good sensitivity for most polymers, but more advanced detectors like multi-angle light scattering (MALS) or viscometers can improve accuracy in determining molecular weight and structure.
Sample preparation: Proper sample preparation (e.g., ensuring uniform dissolution in solvent) ensures better accuracy.
While GPC is generally highly accurate for molecular weight analysis, minor calibration errors or improper sample preparation may affect results.