W. E. Morf

Evaluation of the optimum composition of neutral-carrier membrane electrodes with incorporated cation-exchanger sites

Abstract Selectivities were measured for membrane electrodes containing a given amount of a neutral carrier (ETH 1692) and varying amounts of the additive potassium tetrakis( p -chlorophenyl)borate. The pronounced selectivity changes induced by the additive agreed with a theoretical model. Both theory and experiment confirmed that an optimum composition of the membrane exists. Ideally, sensors for monovalent cations should contain only small amounts of the additive, whereas sensors for divalent cations should contain a molar ratio of additive/carrier of about 0.7 (for 1:2 cation/carrier complexes). Also described are the new desk-computer programs used for the reduction, evaluation, and graphical presentation of ion-selective electrode data.

Carriers for chemical sensors: Design features of optical sensors (optodes) based on selective chromoionophores

Egstract-Macrocyclic and non-macrocyclic ion-selective carriers containing structural elements that heavily change their optical properties in the UV / VIS region upon ion complexation have been introduced earlier as chromoionophores and fluoroionophores, respectively. Here we present different membrane morphologies resulting in a successful design of corresponding sensor membranes with an optical transduction of chemical signals, i.e. for optical measurements of concentrations resp. activities. Workable examples of novel optodes based on chromoionophores are presented, and their response behavior is discussed in more detail.

Anion-selective liquid membrane electrodes based on lipophilic quaternary ammonium compounds

SummaryA series of 15 anion-selective membranes, based on quaternary ammonium compounds of different constitution and on a variety of plasticizers in different compositions of the solvent polymeric membranes, lead throughout to the selectivity sequence

Performance of amperometric sensors based on multiple microelectrode arrays

ClO_4 - > SCN - > I - > NO_3 - > Br - > Cl - > HCO_3 - \sim OAc - \sim SO_4 ^2 - \sim HPO_4 ^2 - .

Organic membranes for miniaturized electrochemical sensors: Fabrication of a combined pO2, pCO2 and pH sensor

. A detailed analysis demonstrates that the selectivity pattern of such systems may be drastically modified only ifa)a mobile, positively charged site with a sufficiently strong and specific interaction with anions is chosen and/orb)an electrically neutral anion-selective membrane component is used.ZusammenfassungEine Reihe von 15 anionenselektiven Membranen, beruhend auf unterschiedlichen quaternären Ammoniumionen und auf verschiedenen Weichmachern, führt auch bei voneinander abweichenden Membranzusammensetzungen durchwegs zur Selektivitätssequenz:

Universal coulometric nanotitrators with potentiometric detection

ClO_4 - > SCN - > I - > NO_3 - > Br - > Cl - > HCO_3 - \sim OAc - \sim SO_4 ^2 - \sim HPO_4 ^2 - .