Aerosol-Based Detection Techniques in the Quality Control of Drug Substances

Stefan Almeling, Head of Division Analytical Chemistry, Laboratory Department, European Directorate for the Quality of Medicines & Healthcare (EDQM), Strasbourg, France

Liquid Chromatography with UV/Vis detection is the most frequently used separation technique in pharmaceutical analysis. However, UV/Vis detection has some important drawbacks when it comes to the analysis of substances lacking a suitable chromophor. Unfortunately this is the case for a number of pharmaceutical substances respectively their impurities. Moreover, in pharmaceutical development it is of crucial importance, not to miss occurring impurities simply due to the selection of an inappropriate detection wavelength.

In the past years a number of evaporation based detectors have been developed with the aim to offer appropriate tools for the analysis of such substances. However, for different reasons, the use of these detectors is in many cases still limited to specific applications and unfortunately – despite their suitability for purpose - often not considered in pharmaceutical analysis.

This presentation aims at providing an overview of the most common aerosol-based detectors (i.e. evaporative light scattering detector (ELDS), corona charged aerosol detector (CAD), nano quantity analyte detector (NQAD) and mass detector (MSD)). Based on a case study the performance of these detectors will be compared with one another. Moreover, several examples from different field of pharmaceutical analysis - ranging from impurities control over counter-ion screening up to the estimation of UV-response factors - will be presented where LC/CAD represents a viable alternative to other detection methods.