Amperometric detection of heavy metal ions in ion pair chromatography at an array of water/nitrobenzene micro interfaces

A novel amperometric detector for heavy metal ions has been developed and successfully applied for ion pair chromatography. The detector is based on the electrochemical transfer of the metal ions across an array of water/nitrobenzene micro interfaces. The ion transfer is facilitated by the neutral ionophores methylenebis(diphenylphosphineoxide) and methylenebis(di- phenylphosphinesulfide). More than eight metals are separated in less than 15 min on an RP18 column using octyl sulfonate as ion pair reagent. For the heavy metals, the limits of decision are 19(Pb²⁺), 9(Zn²⁺), 9l (Co²⁺), 8(Cd²⁺) and 1.6(Mn²⁺) g/L. The applicability of the new method for water samples is demonstrated.