Chromatography of heavy metal cations with formic acid containing mobile phases: Effect of added organic solvents and surfactants on the mobility of cations

Abstract

Chromatography of fifteen metal ions has been performed on silica gel high-performance thin-layer chromatographic plates with mobile phase systems containing formic acid. The effect of protic and aprotic organic modifiers (methanol, ethanol, acetone, acetonitrile, DMSO, and dioxane) and surfactants (SDS, CTAB or Triton X-100) concentrations below and above the critical micellar concentration (CMC) on the retention behaviour of the metal cations was examined. A novel mobile phase system comprising of 1.0 M HCOOH and 1.0 M HCOONa in volume ratio of 7:3 was identified as the best mobile phase for rapid separation and identification of mixtures of Ni²⁺, Cd²⁺ and Ag⁺. The lower limit of detection for Cu²⁺, Ni²⁺, Co²⁺ and Pb²⁺ on HPTLC was determined and semiquantitative determination of Ni²⁺, Pb²⁺, Tl⁺ and Fe³⁺ by spot-area measurement was attempted. The proposed method was successfully applied for identification and separation of nickel, cadmium, and silver from river and industrial wastewater as well as from hydroxide sludge samples.