FLOW-ANALYSIS PRECONCENTRATION OF MG AND ZN USING EMULSIONS FOR FLAMEATOMIC-ABSORPTION SPECTROMETRY

A preconcentration method combining Water/Oil/Water (W/O/W) emulsions with flow injection manifolds has been developed for determinations of Mg and Zn. The system consists of a mixing coil filled with Span 80 a s a surfactant, palmitic acid or di(2-ethylhexyl) phosphate as an extr actant, kerosene as a solvent in the oil phase, and HCl in the inner a queous phase to form W/O emulsions, an extraction coil for the sample solution to form W/O/W emulsions, a phase separator to waste the outer aqueous phase, a dry bath to demulsify W/O emulsions with 2-ethylhexa nol, a phase separator to waste the oil phase, and an air pump to deli ver the concentrated sample solution to the flame atomic absorption sp ectrophotometer. This method proved to be excellent regarding the repr oducibility, the rapidity, and the small quantity of sample, compared with the W/O/W emulsions method without the flow injection manifolds. The signal of flame atomic absorption spectrometry (FAAS) after precon centration of Mg by this method was 2.4 times as large as that before preconcentration. Also, this method suppressed some interferences. The system was applied to FAAS determinations of Mg and Zn in duralumin a lloys and Zn in commercial reagents.