A new CE with contactless conductivity detection method for the determination of complex cationic compositions:...

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 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 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.