Voltammetric Lithium Ion-Selective Electrodes Based on Ion Transfer at the Oil/Water Interface Facilitated by Neutral Ionophores

Abstract

Voltammetric measurements were performed for the transfers of Li+ and Na+ at an oil/water interface facilitated by neutral ionophores including 14-crown-4 derivatives. For the organic solvent, nitrobenzene, o-nitrophenyloctylether (NPOE) and o-nitrophenylphenylether (NPPE) were examined. The interface between water and NPPE containing 20 mM dibenzyl-l4-crown-4 was found to serve best for the ion-selective-electrode (ISE) surface for the voltammetric determination of Lit A test of this voltammetric Li+-ISE using artificial serum showed that the interference from a large amount (ca. 140 mM) of Na+ in blood can be easily avoided by detecting the Na+ concentration simultaneously with the same electrode.

Pulse Amperometric Detection of Lithium in Artificial Serum Using a Flow Injection System with a Liquid/Liquid-Type Ion-Selective Electrode

“…The observable current flowing through the O/W interface due to the facilitated Li + transfer is proportional to the Li + concentration in the W-phase (i.e., the sample solution), provided that the ionophore is added in large excess. In the previous paper, we confirmed a certain applicability of this system to the serum Li + assay by voltammetric measurements with artificial serum under quiescent conditions (i.e., in batch measurements). Nevertheless, there still remained a serious problem with the interference from Na + .…”

“…Facilitated transfer of Li + across the O/W interface by neutral carriers such as crown ethers, − acyclic ligands, ,− and 1,10-phenanthroline has extensively been studied. In the preceding study, we prepared voltammetric Li + ISEs using several neutral ionophores and organic solvents and then showed that a combination of dibenzyl-14-crown-4 (DBz14C4) and o -nitrophenyl phenyl ether ( o -NPPE) led to the best Li + /Na + selectivity (∼240 ). Figure shows the principle of the voltammetric Li + ISE.…”

“…In this study, we have applied this Li + ISE to an amperometric detector of the FIA system in which a cation-exchange column is employed for separating Li + and Na + to some degree in advance.

1 Principle of the voltammetric Li + ISE based on the facilitated transfer of Li + at the o -NPPE/W interface by DBz14C4

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Fabrication and Optimization of Fiber-Based Lithium Sensor: A Step toward Wearable Sensors for Lithium Drug Monitoring in Interstitial Fluid

“…Many different analytical methods have been developed for the determination of Li + concentrations including spectrophotometry, 2,3 flame atomic emission spectroscopy (FAES), 4 flame atomic absorption spectroscopy (FAAS), 5−7 inductively coupled plasma atomic emission spectrometry, 8 inductively coupled plasma mass spectrometry, 9,10 spectrofluorometry, 11,12 electrophoresis, 6 and the use of optical chemical sensors. 13 Electrochemical methods have also been developed that include pulse amperometry, 14 voltammetry, 15,16 and potentiometry. 17,18 The most commonly used laboratory methods are FAES, FAAS, and potentiometry using ion-selective electrodes (ISE).…”

“…Many different analytical methods have been developed for the determination of Li + concentrations including spectrophotometry, , flame atomic emission spectroscopy (FAES), flame atomic absorption spectroscopy (FAAS), − inductively coupled plasma atomic emission spectrometry, inductively coupled plasma mass spectrometry, , spectrofluorometry, , electrophoresis, and the use of optical chemical sensors . Electrochemical methods have also been developed that include pulse amperometry, voltammetry, , and potentiometry. , The most commonly used laboratory methods are FAES, FAAS, and potentiometry using ion-selective electrodes (ISE). , Recently, point-of-care devices based on microchip capillary electrophoresis, − paper-based potentiometry, and a finger stick device have been developed specifically to provide decentralized lithium monitoring. All the above-mentioned methods still require invasive blood sampling.…”