Liquid chromatography with charged aerosol detection (LC-CAD)
Liquid chromatography with charged aerosol detection (LC-CAD) analysis is a powerful technique used for polysorbate quantification and profiling.
After a separation step via high-performance liquid chromatography (HPLC), the column eluent is nebulized by a nitrogen flow, the mobile phase is evaporated together with other volatile components. In the case of CAD, the analyte particles are subsequently positively charged by a secondary nitrogen stream. The final detection of these dried particles, all nonvolatile, takes place by means of light scattering (photomultiplier) or level of electrical charge (electrometer) for CAD, respectively.
LC-CAD in combination with a product-specific sample preparation protocol to remove protein, is Coriolis’ workhorse for polysorbate quantification. Depending on the LC-protocol the main subclasses of polysorbate are resolved and degradation kinetics can be followed in a straightforward way.
For a more in-depth analysis of polysorbate degradation, Coriolis is performing liquid chromatography coupled mass spectrometry [LC-MS] analysis.
Besides surfactant characterization, CAD analysis finds application for excipient quantification in general.