The quantification of potassium using a quartz crystal microbalance

Abstract

N,N'-dibenzyl-4,13-diaza-18-crown-6 (A) and bis[(benzo-15-crown-5)-4'-ylmethyl] pimelate (B) were tested as coatings for two piezoelectric crystals for potassium quantification. Both sensors showed stability, reversibility and sensitivity characteristics that allowed their use in quantitative analysis. However, compound A is much more sensitive to potassium than B. Compound A also shows a larger relative sensitivity for potassium with regard to sodium than B. A pharmaceutical sample of known composition was analysed both by an acoustic wave sensor with a crystal coated with compound A and by conductivity. No statistically significant difference in the median of the results was found (alpha = 0.05), although precision is superior for the conductivity methodology. Performance of the sensor in terms of frequency stability and selectivity was improved by the incorporation of PVC, a plasticizer and a lipophilic salt in the coating composition. Limits of detection found for potassium were 1.92 ppm, or 1.75 ppm for a crystal with a frequency decrease due to coating of 2.9 kHz or 3.9 kHz, respectively. Selectivity coefficients (fixed interference 80 ppm) for potassium over Na, Ca, Al, Zn, Mg, and Fe ranged from 0.103 to 0.332.

30 s Response Time of K+ Ion‐Selective Hydrogels Functionalized with 18‐Crown‐6 Ether Based on QCM Sensor

“…Figure f shows the K + ion‐recognition processes for the hydrogel films. This reaction was reversible in aqueous conditions . The combination of K + with the 18‐crown‐6 ether is a 1:1 ratio, where K + forms a coordinate bond with the oxygen atom on the 18‐crown‐6 ether.…”

Photonic Crystal-Based Sensing and Imaging of Potassium Ions

“…Monitoring of potassium ions is of large interest in point-of-care diagnostics on a daily basis, because it is a highly significant parameter for recognizing the occurrence of various kinds of infarction. Moreover, potassium ions govern numerous physiological processes [1], such as the control of blood pressure, nerve signal transmission and muscular strength [2,3]. They regulate the growth of cells [4], affect endothelial function [5] and maintain a concentration gradient (and, thus, the Donnan potential)…”

Aptasensor for label-free square-wave voltammetry detection of potassium ions based on gold nanoparticle amplification

“…[10][11][12][13][14][15] Potassium ions, which is the most abundant metal ion in cells, play essential roles in biological systems, such as nerve transmission, maintenance of muscular strength and extracellular osmolarity, enzyme activation, apoptosis of a cell, regulation of blood pressure, pH, and the concentration of other ions in living cells. [16][17][18][19][20][21] Normal serum K + levels are between 3.8 and 5.4 mmol L À1 , 22 the abnormal K + concentration is a symptom of several diseases, including kidney diseases, alcoholism, anorexia, bulimia, heart disease, diabetes, AIDS and cancer. 23 Therefore, it is very important to be able to assess this ion at trace level with high sensitivity.…”