Contactless Conductivity Detection of 14 Inorganic Cations in Mineral and Phytotherapeutic Formulations after Capillary Electrophoretic Separation

This work describes the separation and determination of 14 inorganic cations (NH4+, K+, Ca2+, Na+, Mg2+, Mn2+, Tl3+, Cr3+, Pb2+, Cd2+, Zn2+, Cu2+, Co2+, and Ni2+) as nutrients and contaminants in mineral and phytotherapeutic samples. The separated species were detected by capacitively coupled contactless conductivity detection (C4D) using working electrolytes based on 30 mmol L−1 2‐N‐morpholinoethanesulfonic acid (MES)/histidine, 1.5 mmol L−1 18‐crown‐6 ether, and 1 mmol L−1 citric acid (pH 6.0) as complexing additives for co‐migrating cations. The methodology was evaluated and validated for the cations and it was found to be reliable for determining inorganic cations in samples of mineral fertilizers and medicinal plants used in the phytotherapy.