Stripping Voltammetric Determination of Choline Based on Micro-Fabricated Composite Membrane

Abstract

A novel stripping voltammetric method for the determination of non-redox ionic species is presented. Using choline ion (Ch + ) as an example, we demonstrate how a micro machined PVC-NPOE gel membrane can be used to accumulate Ch + ion under potentiostatic steady-state conditions. The amperometric stripping of the target ion can be carried out by any voltammetric method but we presently illustrate the principle using linear sweep voltammetry. The effect of accumulation time, accumulation potential and choline ion concentration has been examined. The present work also includes the quantitative study of an enzyme reaction generating choline, namely the reaction of calcium phosphocholine with alkaline phosphatase. With this experimental approach, µg ml -1 concentration level of alkaline phosphatase enzyme can be determined.

Electrochemistry of dopamine at the polarised liquid|liquid interface facilitated by an homo-oxo-calix[3]arene ionophore

“…The organic electrolyte salt was obtained by metathesis of potassium tetrakis(4-chlorophenyl) borate and bis(triphenyl-phosphoranylidene) ammonium chloride according to the protocol described in Refs. [26,27].…”

Simple Ion Transfer at Liquid|Liquid Interfaces

“…These interfaces can be used for understanding and developing practical electroanalytical processes and devices [9,32,36,563,564]. The electrochemical methods applied to liquid|liquid interfaces have proved a useful tool for the determination of ionic analytes not easily oxidized or reduced [36,45,119,121,136,141,149,153,254,273,336,496,562,[564][565][566][567][568][569][570][571][572][573][574][575][576][577][578][579][580].…”

Electrochemistry at liquid/liquid interfaces: methodology and potential applications

“…These two recent results have shown that this type of detector can replace conductometric detectors for the detection of non-redox ions which suffer from lack of selectivity compared to optical or direct amperometric detectors. Other applications of the ionodes include choline ion sensors [77] by a direct ion transfer reaction and enzyme sensors where stripping voltammetry is used to accumulate the ion of interest in the gel layer resulting in the enhancement of the detection limit [76]. …”