Ionic sensors

An ionic sensor for the ions involved in the above reactions can be used. The choice is usually dictated by the conditions of the sample. Thus, at low pH, the species of choice would be NHj) and at high pH it would be HCO. For the neutral pH range the best performance would be obtained from monitoring the changes of the pH itself. 

Oliveira et al. [32] L-Glutamate Commercial soups L-Glutamate decarboxylase/ in glass beads Potentiometric ionic sensor ... 

Ionic sensors based on molecularly imprinted polymers... 

It can be seen from the above discussion that the use of nanoionic materials for gas sensors is a natural extension to the findings already reported. Nanosized materials offer advantages in terms of improved sensor response due to the much higher surface areas available. However, the definition of a nano ionic sensor material can be very broad the nanoionic component of the sensor material might refer to the bulk majority phase, but alternatively it could refer to a dispersed catalytic or dopant phase, or even a combination of both. 

Janke, D. (1990) Recent development of solid ionic sensors to control iron and steel bath composition. Solid State Ionics, 40/41, 764-9. 

Murray, G.M. Uy, O. Ionic sensors based on molecularly imprinted polymers. Tech. Instrum. Anal. Chem. 2002, 23, 441-465. 

Sales et al. (2001) developed a potentiometric sensor for the determination of tartaric acid. Tartrate-sensitive electrodes were constructed, comprising poly(vinyl chloride) membranes. Various membrane compositions were evaluated and the one combining an ionic sensor (bis(triphenylphosphoranylidene)ammonium chloride), 4-ferf-octylphenol, and o-nitrophenyl octyl ether was selected. The analytical characteristics of this electrode were evaluated using a single-line flow injection manifold. The accuracy of the developed method was demonstrated for the determination of tartaric acid in red and white wine samples. 

In ionic sensors, such systems are called ionic bridge or internal reference. As the second electrode, an external reference is used for instance, a calomel electrode with a Uquid junction. 

The results reported in this work indicate that cyclodextrins chemically bonded to gel (PMHS) or incorporated in polymer matrix (PVC) appear as promising sensitive membrane for heavy ion sensors. The performances of ionic sensors are related to their aptitude to be used several times. The effect of the pH solution on the sensitivity of the sensors was also investigated for the P-CD/PMHS membrane towards Pb(Il) ions. The obtained results indicate a decrease of the membrane sensitivity going from neutral to acidified solutions. This indicate that the stabUily of the cyclodextrine complex depends on the acidity of the tested solution. 

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