ESA's CAD improves detection of API impurities

The firm's new Corona charged aerosol detector (CAD) apparatus enables the routine detection and measurement of low-nanogram levels of organic impurities.

Many of the impurities present in pharmaceutical preparations are difficult to measure with traditional technologies because they have poor UV signal or may lack any chromophore at all. This problem is especially acute with newer pharmaceutical preparations involving the formulation of proteins, peptides, or complex molecules in lipid or polymer-containing mixtures.

The firm explained that accurate quantification of impurities is critical to both the initial development of the drug product in question and subsequent industrial scale manufacture ESA added that the level of impurities, such as unreacted starting materials, by-products, intermediates, degradation products, reagents, ligands, and catalysts, must be tightly controlled and heavily regulated to ensure patient safety.

Advantages over traditional HPLC​

Data from trials of CAD indicate that the system's isocratic high performance liquid chromatography (HPLC) capabilities can reproducibly and accurately measure non-chromophore and chromophore-containing impurities down to the 0.005 per cent level, independent of chemical structure.

The study also demonstrated the high degree of precision that the system allows as well as its effective dynamic detection range, which is capable of identifying impurities in microgram to nanogram quantities.

ESA explained that the system has many advantages over other HPLC detection methods (UV, ELSD, CLND, and LC-MS) that historically have been used for impurity testing. These include low-nanogram sensitivity, a dynamic range exceeding four orders of magnitude, good precision response factors that are independent of structure, and no/low analyte level response 'drop-off'.

ESA said that its system is the ideal complement to ultraviolet (UV) detection, because it allows the identification and characterisation of non-volatile and many semi-volatile compounds, which is of particular benefit for the identification of organic impurities.

The firm also argued that the systems' robust, reliable design and plug-and-play functionality means that it can be incorporated into existing manufacturing setups and that minimal operator training is required.