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

ABSTRACT

A CE with contactless conductivity detection methodology using a novel background electrolyte for the separation and determination of 17 metal cations (Cs+ , Rb+ , K+ , Ca2+ , Na+ , Mg2+ , Mn2+ , Sr2+ , Li+ , Ba2+ , Fe2+ , Pb2+ , Cd2+ , Zn2+ , Co2+ , Cu2+ and Ni2+ ) and ammonium has been investigated. The buffer, based on lactic acid and ß-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 Fe2+ and Pb2+ . 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.