Flow analysis: potentiometric sensors

The flow of electrical current in a circuit with an electrolyte causes ionic transport between the electrodes, which affects the electrode reaction. The application of a small perturbation in a potentiometric sensor has been shown to improve the sensor performance in what is referred to as the current reversal method [24—26]. An analysis of the response to such a perturbation can also be used as a diagnostic tool to evaluate sensor performance during operation [27, 28]. Similarly, the application of a bias voltage to a potentiometric sensor can be used to affect the performance of the sensor, such as the relative responses to NO and NO2 gases [29—31]. The response to voltage or current perturbations can also be used as the sensor signal. 

S.S.M. Hassan, H.E.M. Sayom, S.S. Al-Mehrezi, A novel planar miniaturized potentiometric sensor for flow injection analysis of nitrates in wastewaters, fertilizers and pharmaceuticals. Anal. Chim. Acta 581 (2007) 13-18. 

Potentiometric detectors and formation of new t3 pes of sensors including detectors without internal solution (all-solid-state). The composition of ion-selective layers was considerably and aptly modified. New solutions and additives in the membrane electrodes were used and tested looking for analogy with biological membranes. Special applications of such electrodes in medicine were studied. Development of methods of the flow analysis, which was introduced to analytical chemistry in the last quarter of the twentieth century. A number of original results in the methodology of that method were obtained at the University of Warsaw, especially in the use in detection of electrochemical techniques. Number of interesting and new results were obtained in electrophoretic methods. 

Teixeira MFS, CavaUieiro ETG, Bergamini ME, Mmaes PC, Bocchi N (2004) Use of carbon paste electrode modified with spinel-type manganese oxide as potentiometric sensor for lithium ions in flow injection analysis. Electroanalysis 16 633-639... 

Flow-cell (or flow-through cell) — is a device through which fluid may be driven using an external force. Often of rectangular or tubular form for electrochemical applications, a cell may incorporate a variety of different - sensors, e.g., voltammetric [i] or potentiometric [ii], these devices can also be used in conjunction with spectroscopic analysis. Flow-through cells are also used extensively in synthetic and technical applications - Swiss-role cell. 

J. F. Coetzee and C. Gunaratna, Potentiometric Gas Sensor for the Determination of Free Chlorine in Static or Flow Injection Analysis Systems. Anal. Chem., 58 (1986) 650. 

The common spectrophotometric method for creatinine detection is based on the Jaffe reaction between creatinine and picric acid in alkaline solution to form a red-yellow complex. However, substances of endogenous and exogenous origin usually cause interference. In spite of these problems, the colorimetric method of Jaffe is still used today for the determination of creatinine in biological samples.A batchwise kinetic procedure and flow injection analysis have shown the possibility to determine creatinine in human urine samples by this reaction, free from any systematic error.Enzymatic methods have been reported to increase specificity/selectivity but still suffer from interferences. To avoid these problems, new analytical methods were developed. Several electtoanalytical techniques, based on potentiometric or amperometric detection, are available. Potentiometric methods using several sensors and biosensors were known for the... 

Hassan, S. S. M., S. A. Marei, I. H. Badr, and H. A. Arida. 2001. Flow injection analysis of sulfite ion with a potentiometric titanium phosphate-epoxy based membrane sensor. Talanta 54 773-782. 

Direct, sensitive, selective, and rapid biosensors have been developed based on OPH, organophosphoms acid hydrolase (OPAA), and parathion hydrolase (PH). Schoning and co-workers developed a silicon-based capacitive field-effect pH sensor, which can detect 2 pM of paraoxon. " The same group prepared ampero-metric and potentiometric biosensor chips by thin-film techniques and integrated them in a flow-injection analysis (ElA) system, which can detect different OP pesticides at the low pM concentration range.Recently, mesoporous carbon and carbon black-modified electrodes have been used to develop an amperometric biosensor based on OPH. With increased sensitivity, the biosensor can detect as low as 0.12 pM (36 ppb) paraoxon. ... 

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