Bettersize
BeSEC

Molecular Weight Analyser

Measure the absolute molecular weight
Dual-angle light scattering detector
Molecular weight range: 1 kDa to 2 GDa

Beckman Coulter LS 13 320 XR Laser Diffraction Particle Size Analyser 21 CFR Part 11

A dual-angle light scattering detector that can be used to measure the absolute molecular weight of proteins, synthetic polymers, and natural polymers, as well as molecular size in terms of radius of gyration (Rg).

Proteins: Determine molecular weight, oligomer state, and aggregates
Polymers & Polysaccharides: Analyze molecular weight distribution and size
No column calibration required since Mw is independent of elution volume
Low-angle detection enables accurate molecular weight
Compatible with any GPC or SEC system

Step into the future of chromatography with the BeSEC Series. Designed as a next-generation light scattering detector, the BeSEC transforms conventional SEC/GPC workflows into powerful platforms for absolute molecular weight analysis.

Unlike traditional methods that rely on retention time, the BeSEC delivers first-principles data, ensuring unmatched accuracy for researchers in biopharmaceuticals, advanced polymer science, and food chemistry— accelerating the path from discovery to market.

Key Features and Benefits

Key Features

Detection angles: 7° and 90°
Molecular weight range: 1 kDa to 2 GDa
Supports radius of gyration Rg > 12 nm
Homopolymer and protein modes
Acquires RI, UV, and start signals
Intuitive software with real-time analysis
18 μL flow cell reduces band broadening

Benefits

Proteins: Determine molecular weight, oligomer state, and aggregates
Ppolymers and polysaccharides: Analyze molecular weight distribution and size
No column calibration required since Mw is independent of elution volume
Low-angle detection enables accurate molecular weight
Compatible with any SEC or GPC system

Technical Specs

Technology	BeSEC LS1: 1 kDa to 20 MDa* BeSEC LS2: 1 kDa to 2 GDa*
Rg	BeSEC LS1: N/A BeSEC LS2: > 12 nm*
Detection Angle	BeSEC LS1: RALS (90°) BeSEC LS2: LALS (7°) and RALS (90°)
Laser Source Type	Diode Laser
Laser Power	10 mW
Laser Wavelength	640 nm
Sample Cell Volume	18 µL
Acquisition Rate	5 Hz
Dynamic Range	+/- 2500 mV
Connection to PC	USB
Measurement Modes	Homopolymer mode, protein mode
Output Results	BeSEC LS1: Mn, Mw, Mz, Mp, Pd, dn/dc, Concentration, Mw distribution BeSEC LS2: Mn, Mw, Mz, Mp, Pd, dn/dc, Concentration, Mw distribution, Rg
Analog Outputs	RI, UV and start signals
Solvent Compatibility	Aqueous and organic solvents
Wetted Parts	PTFE, PEEK, glass, stainless steel
Power Supply	AC 100-240 V, 50-60 Hz, 4.0 A
Dimensions	450 × 325 × 157 mm (= 17.7″ × 12.8″ × 6.2″)
Weight	11 kg (= 24.2 lbs)

Technology

Determining Absolute Molecular Weight

with the Light Scattering Detector

In size exclusion chromatography (SEC), separation depends only on the hydrodynamic size of the molecules. Larger molecules are unable to penetrate the pores of the stationary phase and elute earlier, while smaller molecules enter the pores and elute later. The separation mechanism is purely physical, and no chemical or adsorptive interactions occur between the solute and the stationary phase.

Breaking Free from Column Calibration

How the BeSEC Improves SEC/GPC Workflows

Traditional SEC/GPC systems without light scattering detection provide only relative molecular weight

These systems require calibration with a series of polymer standards to create a calibration curve of molecular weight versus retention volume.

Conventional methods that rely on retention volume introduce significant bias

Polymers with similar hydrodynamic size can elute at the same time yet differ greatly in molecular weight due to structural variations. Without light scattering detection, these differences remain hidden, making it impossible for traditional SEC or GPC to accurately distinguish between such samples.

Applications

Assess PET grade