Evaluation of contactless conductivity detection for the determination of UV absorbing and non-UV absorbing species in reversed-phase high-performance liquid chromatography

A capacitively coupled contactless conductivity detector (C4D) was used for the determination of three groups of ionizable species in reversed-phase HPLC with isocratic elution. These were non-steroidal anti-inflammatory drugs which are arylpropionic acid derivatives and represent anionic analytes, beta-blockers which are amines and therefore cationic, and zwitterionic amino acids. Optimization of the eluents led to detection limits in the order of 1 μM for all species. The precision in peak areas was typically between 0.2 and 2.1% and calibration curves were linear up to 500 μM. The determination of ibuprofen, acetylsalicylic acid and atenolol in real samples was also demonstrated by direct injection of dissolved pharmaceutical formulations into the HPLC-C4D system.