Integration of a microextraction system on a glass chip: Ion-pair solvent extraction of Fe(II) with 4,7-diphenyl-1,10-phenanthrolinedisulfonic acid and tri-n-octylmethylammonium chloride

An ion-pair solvent extraction was performed in a microchannel fabricated i n a quartz glass chip. The aqueous solution of Fe-bathophenanthrolinedisulf onic acid complex and the chloroform solution of tri-n-octylmethyl-ammonium chloride were introduced into the microchannel, and a parallel two-phase l aminar now was formed. The ion-pair product extracted in chloroform was mon itored by the thermal lens microscope. The ion-pair product was gradually e xtracted from aqueous solution into chloroform when the flow was very slow or stopped, while nothing was extracted into chloroform when the flow was f ast. The time for extraction in the present 250 mu m microchannel, 45 s, ro ughly coincided with the molecular diffusion time, and the extraction time was at least 1 order shorter compared with the ordinary extraction time usi ng a separatory funnel and mechanical shaking. The micro-space in the micro channel was characterized by the large specific interface area and short di ffusion distance, and these characteristics may contribute to highly effici ent extraction without mechanical shaking. The success of this molecular tr ansport may lead to the integration of more complicated separation and chem ical operations on a microchip and more applications.