SEC-RI Analysis Laboratory: Advanced Characterization of Macromolecules
Size exclusion chromatography (SEC) is the benchmark technique for separating macromolecules.
Within its analytical platform, FILAB, a SEC RI laboratory, uses coupling with a refractive index detector (RI) to characterize the structure of your polymers and organic compounds, validate their compliance, or diagnose the origin of a failure.
Your need: rely on a SEC RI testing laboratory to secure your product or material developments or failures
SEC RI Analysis
GPC/SEC-RI analysis (refractometry) is used to characterize any polymer or complex blend whose structural compliance needs to be verified, to detect physical degradation (aging, shear), or to identify impurities and poorly distributed additives affecting the material’s properties.
Principle of SEC RI analysis
The SEC-RI separates macromolecules according to their hydrodynamic volume to establish an accurate map of their molar mass distribution (Mn, Mw, Ip). This universal coupling makes it possible to characterize the homogeneity of your polymers and additives, thereby ensuring the compliance and performance of your industrial materials.
Did you know? We generally refer to GPC for synthetic polymers (plastics, resins, elastomers), which are often soluble in organic solvents. The term SEC is used for biomolecules (proteins, polysaccharides) analyzed in aqueous media.
Broad compatibility: SEC-RI for macromolecular materials
SEC-RI analysis is versatile: it applies to synthetic polymers (PE, PP, PVC, PS…), biopolymers (proteins, polysaccharides), resins, as well as complex blends of additives and oligomers.
If your product has a macromolecular structure, SEC-RI is probably the right technique.
Nos solutions : l'analyse par couplage GPC-RI/LS (RALS/LALS)
The FILAB laboratory provides you with its expertise in GPC (SEC) analysis by coupling RI and LS in order to characterize your polymer materials and determine their molar mass. In this context, FILAB offers the following services:
Our services using GPC-RI/LS coupling (RALS/LALS)
To go beyond simple comparison with standards, FILAB offers coupling SEC-RI with light scattering (Light Scattering – LS), including RALS (Right Angle Light Scattering) and LALS (Low Angle Light Scattering) technologies:
Average molecular mass control and molar mass distribution of polymer materials
Absolute molar mass control
Conventional molar mass determination (PS equivalent)
Conformation analysis: study of chain structure (linear vs branched) and calculation of the radius of gyration.
Method development and validation: development of specific protocols for your innovative molecules.
Failure analysis on polymers: fracture, deformation, surface...
Polysaccharide characterization
Absolute molar mass: determination of the true molar mass of your polymers without resorting to relative calibration (Polystyrene or PMMA standards).
Determination of dn/dc: precise measurement of the refractive index increment, an essential parameter for absolute mass calculations in light scattering.
SEC RI Technical Advantages
Using a Refractive Index (RI) detector offers major advantages for routine control and expert analysis:
- Universal detection: the RI detector is considered "universal" because it measures the difference in refractive index between the pure solvent and the eluted solution. It therefore detects nearly all polymers, even those without chromophores (unlike UV).
- Stability and reliability: this is a robust method, perfectly suited to quantitative analysis and production monitoring.
- Sensitivity : enables precise detection even at low sample concentrations in solution.
Analytical Objectives of a SEC RI Analysis
The goal of a SEC RI analysis is to obtain a complete fingerprint of the molecular distribution of a sample. Unlike other bulk mass measurement methods, it makes it possible to:
- Determine the number-average molar mass (Mn) and the weight-average molar mass (Mw).
- Calculate the polydispersity index (Ip), a crucial indicator of polymer homogeneity.
- Identify the presence of high- or low-molecular-weight fractions (oligomers) that may affect the material’s final properties.
- Ensure the conformity of raw materials before production.
Applications of the SEC RI Technique
Synthetic Polymers: Polyethylene (PE), Polypropylene (PP), PVC, Polystyrene, etc.
Medical Devices: characterization of resorbable polymers and degradation monitoring.
Biopolymers and Polysaccharides: study of starch, cellulose, hyaluronic acid, or chitosan.
Cosmetics and Pharmaceuticals: verification of compliance for excipients and macromolecular active ingredients.
Why choose FILAB, a SEC RI analysis laboratory?
Choosing FILAB for your SEC RI expertise means benefiting from tailored support and recognized technical excellence:
- A state-of-the-art analytical platform : our equipment enables us to work with a wide range of solvents (aqueous or organic such as THF, DMF, hexafluoroisopropanol...) to adapt to the solubility of your products.
- An expert team : our engineers and PhD chemists in polymer chemistry help you interpret the results and solve your R&D or failure analysis issues.
- Responsiveness and quality : FILAB is an ISO 17025-accredited laboratory (scope available on www.cofrac.fr), ensuring the reliability and impartiality of every SEC RI analysis.
Our SEC / GPC technical variants
Analysis by size exclusion chromatography includes several technical variants depending on the molecules studied and the measurement conditions.
Our FAQ
The GPC (Gel Permeation Chromatography) is a type of SEC (Size Exclusion Chromatography). The term "RI" simply refers to the refractive index detector used at the column outlet to quantify the separated molecules.
The RI detector alone provides a "relative" molar mass (compared with standards). Coupling with light scattering (SEC-LS) makes it possible to obtain the absolute molar mass and information on the molecule's structure (branching), without relying on a calibration range.
Solubilization is the key step. The FILAB laboratory has a wide range of solvents: organic (THF, DMF, Hexafluoroisopropanol/HFIP, Chloroform...) or aqueous (pH-controlled buffers).
We adapt the choice of solvent to the chemical nature of your sample.
As a general rule, an amount of 50 to 100 mg is sufficient to carry out a complete analysis. However, for very dilute or valuable samples, our experts can adapt the protocol.
Yes, FILAB is an ISO 17025 accredited laboratory by COFRAC (scope available at www.cofrac.fr).
This accreditation guarantees the rigor of our processes, the traceability of measurements, and the technical expertise of our teams for your SEC RI analysis.
You can fill out the form or contact us by phone. To help us respond quickly, please tell us the nature of your sample, its presumed solubility, and the purpose of your study (routine control, R&D, or expert assessment following a defect). Our engineers will get back to you promptly.
Turnaround times vary depending on the nature of the analysis and the complexity of the expert assessment project.
FILAB is committed, however, to providing fast turnaround times tailored to your constraints and industrial urgencies.
