Development of Li+ Selective Microelectrode Using PPy [3,3'-Co(1,2-C2B9H11)2] as a Solid Contact

Abstract

Planar all solid-contact ion-selective microelectrodes (ASC-µISEs) with a conducting polymer (polypyrrole doped with cobaltabis(dicarbollide) anion [3,3'-Co(1,2-C2B9H11)2]) as a solid contact layer between the polymeric membrane sensitive to lithium (Li) and the gold (Au) substrate were prepared and investigated. The N,N-dicyclohexyl-N',N'-diisobutylyl-cis-cyclohexane-1,2- dicarboxamide (ETH 1810) was used as ionophore for Li recognition. The developed microelectrodes show a linear response for Li+ concentration between 6´10-5 M and 1´10-1 M with slope of 53±1 mV per decade and exhibits remarkably enhanced selectivity for Li over other cations. The calibration plots using artificial serum containing three different levels of sodium chloride (NaCl) (135, 145 and 155 mM) as a background electrolyte were shown a linear response with a slope of 50 mV per decade in the clinical range of interest (0.7-1.5´10-3 M Li+). The developed microelectrodes will be used to determine Li+ concentrations in serum samples of manic-depressive patients under Li treatment.

Keywords

• Lithium-selective
• All solid-contact ion-selective microelectrode
• PPy [3
• 3'-Co(1
• 2-C2B9H11)2]
• Potentiometry.