Recent applications of the Charged Aerosol Detector for liquid chromatography in drug quality control

High performance liquid chromatography (HPLC) methods with UV/vis detection are the most widespread analytical procedures in modern pharmaceutical applications, but reach their limitations when it comes to non-chromophore molecules. Hence, instead of using tiresome derivatization procedures, many liquid chromatography methods make use of the so-called aerosol-based universal detectors, namely the evaporative light scattering detector (ELSD), the condensation nucleation light scattering detector (CNLSD) and the charged aerosol detector (CAD). Amongst these, the CAD, being the youngest (introduced in 2005) of these three options, is often described as the most easy-to-use detector and is stated to exhibit sufficient sensitivity and good linearity of signal in a dedicated range of concentration. Therefore, this review sets its focus on the recent applications of the CAD for active pharmaceutical ingredients, excipient analysis as well as botanical applications. Alongside the post-column solvent addition techniques, the new CAD's ability to adjust the evaporation temperature and the possibility to use an integrated power function for signal linearization are reviewed as previously unavailable, new parameters for optimization.