Rapid Determination of Alkali and Alkaline Earth Metal Ions by Capillary Electrophoresis-Ion Chromatography

Six cations of alkali and alkaline earth metals,i.e.,Li+,Na+,K+,Mg2+,Ca2+ and Ba2+,were separated and determined by the rapid capillary electrophoresis (CE) and ion chromatography (IC) within 3.5 min,using a set of self-assembled instruments.The CE-IC analysis was performed in a buffer solution of 25 mmol·L-1 2-(N-morpholino) ethanesulfonic acid (MES) and L-histidine (L-His) system of pH 6.0 in the presence of 20 μmol·L-1 CTAB,and under the working condition of ① separation voltage 10 kV,② excitation voltage 60 V and ③ excitation frequency 120 kHz.The capacitively coupled contactless conductivity detection was adopted in the determinations.Linear relationships between values of peak area and concentration of all the 6 metal ions were found in the range of 4.0-64.0 μmol·L-1.Detection limits (3S/N) were found to be 1.0 μmol·L-1 for K+,Ba2+,Ca2+,Na+ and Mg2+,and 2.0 μmol·L-1 for Li+.