Separation and sensitive detection of lanthanides by capillary electrophoresis and contactless conductivity detection

A rapid and sensitive capillary zone electrophoresis method for the simultaneous separation and determination of lanthanide ions, combined with capacitively coupled contactless conductivity detection (C⁴D), is reported. The influence of experimental parameters on separation was investigated. The optimal separation conditions were obtained when 4.5mM 2-hydroxyisobutyric acid and 1mM acetic acid (HAc) at pH 4.5 were used as buffer solution. Under these conditions, complete separation of all 14 lanthanide ions was achieved in 6 min. With the use of the C⁴D detector, the sensitive detection of non-UV active lanthanide ions was achieved without the need of a UV active ligand or a visualization agent. The sensitivities were further enhanced with a sample stacking procedure. The limits of detection were to be found between 2.77 and 8.26 nmol/L and the limits of quantification were between 9.29 and 27.5 nmol/L for 14 lanthanide ions.