On-Chip Integration of Neutral Ionophore-Based Ion Pair Extraction Reaction

Abstract

Integration of a neutral ionophore-based ion pair extraction reaction onto a glass microchip was performed. Since the liquid microspace provides a short molecular diffusion distance and a large specific interfacial area of the liquid−liquid interface, novel attractive analytical features arise such as extremely fast ion sensing and ultrasmall reagent solution volume. In contrast to the slow response time of a standard ion optode, in which the response time is basically governed by slow diffusion of ionic species in the viscous polymer membrane, that of the on-chip ion-sensing system is clearly faster due to the short molecular diffusion distance and low viscosity of organic solution. In this case, the organic solution containing a neutral ionophore and a lipophilic pH indicator dye and the aqueous solution containing sample ion were independently introduced into microchannel to form an organic−aqueous interface. Then determination of the ion was performed by thermal lens microscopy at the downstream of th...