Tips & Tricks: GPC/SEC Increase Resolution and Separation Range
The precision and accuracy of the results depends, amongst other parameters, on the selection of the proper separation columns.
GPC/SEC is used to separate, identify and characterize macromolecules with respect to their molar mass averages and molar mass distribution (MMD). The precision and accuracy of the results depends, amongst other parameters, on the selection of the proper separation columns.
A proper column selection in GPC/SEC always includes finding a compromise between separation range, analytical quality, analysis time and solvent consumption. A wide separation range is required for highest versatility and applicability, a good resolution is required for the in-depth analysis, especially for a detailed MMD. Analysis time and solvent consumption are important especially for quality control in high temperature GPC and when expensive solvents are used.
The dependence of GPC/SEC column characteristics and experimental parameters on the resolution is quite complex. Column material particle size and packing quality, pore size and pore size distribution, solvent viscosity, temperature and flow-rate, as well as sample concentration and other factors influence the mass transfer and, therefore, the resolution.
A measure for the resolution can either be the plate count, N, or (recommended for GPC/SEC) the specific resolution, Rsp. For the specific resolution the peak standard deviation (which is proportional to the peak width) and the slope of the calibration curve are required.
Best of the Week: Food Analysis, Chemical Migration in Plastic Bottles, STEM Researcher of the Year
December 20th 2024Top articles published this week include the launch of our “From Lab to Table” content series, a Q&A interview about using liquid chromatography–high-resolution mass spectrometry (LC–HRMS) to assess chemical hazards in plastic bottles, and a piece recognizing Brett Paull for being named Tasmanian STEM Researcher of the Year.
Using LC-MS/MS to Measure Testosterone in Dried Blood Spots
December 19th 2024Testosterone measurements are typically performed using serum or plasma, but this presents several logistical challenges, especially for sample collection, storage, and transport. In a recently published article, Yehudah Gruenstein of the University of Miami explored key insights gained from dried blood spot assay validation for testosterone measurement.
Determination of Pharmaceuticals by Capillary HPLC-MS/MS (Dec 2024)
December 19th 2024This application note demonstrates the use of a compact portable capillary liquid chromatograph, the Axcend Focus LC, coupled to an Agilent Ultivo triple quadrupole mass spectrometer for quantitative analysis of pharmaceutical drugs in model aqueous samples.
