Multi-Angle Light Scattering Detection (MALS) results in the measurement of absolute molecular weight which is independent from the column calibration. The amount of light scattered (measured by MALS) is proportional to the molar mass of the polymer (M), the concentration (c) of the polymer, and the square of specific refractive index increment (dn/dc). Special procedures must be taken if the sample absorbs or if the sample fluoresces with exicitation at the wavelength of the laser (663.1 nm).
The ViscoStar detector measure specific viscosity. When coupled with a concentration detector as the Optilab rEX, it can be used to derive the intrinsic viscosity. The intrinsic viscosity, in turn can be used to derive the hydrodynamic radius and shape information about molecule in solution. The air-cooled Peltier allows to control temperature from 4-60oC. Operation below ambient temperature requires the flow of dry gas into the temperature - controlled environment.
Equipment
Pump: Waters Alliance HPLC System, 2695 Separation Module.
Two GPC Columns: (1) MZ-Gel SD plus 10E6 Ang (300x8.00 mm), particle size 5 µm
(2) MZ-Gel SD plus 10E4 Ang (300x8.00 mm), particle size 5 µm
from MZ-Analysentechnik GmbH (http://www.mz-at.de).
Detectors:
Wyatt DAWN HELEOS-II (laser 663.1 nm).
Wyatt Optilab rEX (RI).
Waters 2996 Photodiode Array Detector (PDA).
Wyatt ViscoStar.
Solvent: chloroform with 0.25% of TEA
Flow rate = 1 ml/min.
Injection: 100 µL.
MRFN.org is supported by the MRSEC Program of the National Science Foundation. Image in the header is courtesy of CRISP MRSEC.
