A new CE with contactless conductivity detection method for the determination of complex cationic compositions: Application to the analysis of pen inks

A CE with contactless conductivity detection methodology using a novel background electrolyte for the separation and determination of 17 metal cations (Cs + , Rb + , K + , Ca 2+ , Na + , Mg 2+ , Mn 2+ , Sr 2+ , Li + , Ba 2+ , Fe 2+ , Pb 2+ , Cd 2+ , Zn 2+ , Co 2+ , Cu 2+ and Ni 2+ ) and ammonium has been investigated. The buffer, based on lactic acid and β‐alanine, was experimentally compared with other two commonly used electrolytes, showing important improvements, such as shorter analysis times (<11 min), better electrophoretic resolutions and higher detectabilities for certain analytes, such as Fe 2+ and Pb 2+ . The inclusion of other additives such as 18‐Crown‐6 and α‐hydroxyisobutyric acid was studied in order to obtain the best separation of the analytes of interest. The optimised method was applied to the analysis of 11 water‐based pen inks and the determination of their metal composition. The methodology was demonstrated for the comparison and differentiation of pen inks.