الفهرس 
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Abstract
This dissertation includes development and application of some analytical techniques namely potentiometry for determination of thiocyanate, cyanide, some metal (ions) and selenium ions. Novel sensors and modern chemical methods are described, characterized and used for some chemical analyses.
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Chapter one:
This chapter includes a general historical review on potentiometry, the basic principles, theory, historical background characteristics and classification of potentiometric sensors.
Chapter two:
In this section, preparation, characterizations of simple potentiometric poly (vinyl chloride) matrix membrane thiocyanate sensors are described. These are based on the use of Cu (II)-2-[5-bromo-2-pyridylazo)-5-diethylaminophenol] as an electoactive membrane material. The sensor displayed high selectivity in the presence of many anionic species, a wide dynamic response (7.0 x 10-6 to 1.0 x 10-2 mol L-1), a low detection limit (5.6 x 10-6 mol L-1), good sensitivity (-57.5 ± 0.5 mV decade-1), a rapid response (10 s), and the response is unaffected by pH changes from 3.2 - 8. Under the hydrodynamic mode of operation, the sensor exhibited a near-Nernstian slope of -55.9 ± 0.1 mV decade-1 over a concentration range of 1.0 x 10-5 - 1.0 x 10-2 mol L-1 SCN–. The sensors are used for the preparation of tubular detectors for use in a manual and flow injection manifold for continuous thiocyanate ion assay in urine and saliva. Quantization of cyanide in electroplating baths was also described after conversion of the cyanide ion into thiocyanate.
Chapter three:
In this chapter, the preparation, characterization of simple potentiometric picrate poly (vinyl chloride) matrix membrane sensors for fast determination of selenium is described. The sensing membranes are based on the use of a [(picrate)(nitron)] and [(picrate)2(Fe(bphen)3] in PVC based membrane sensors selective for picrate ion. these electrodes are very easy to prepare , Under the static mode of operation, the sensors displayed high selectivity and sensitivity, a wide range (3 x 10-5 to 1 x 10-2 and 4.6 x10-6 to 1.0x10-2 molL-1 ) , a low detection limit (7.4x10-6 and 3.0x10-6 mol L-1), very fast response time ,and the sensors exhibit near Nernstian slope of -57.2 ± 0.8 and-58.8 ± 0.5 mV decade-1 for [(picrate)(nitron)] and [(picrate)2(Fe(bphen)3], respectively, a rapid response (10 s), and the response is unaffected by pH changes over the range 4.0 – 10.5.
Determination of selenium (IV) is based on its catalytic effect on the reduction of picrate by sodium sulfide in alkaline media. The reaction rate was followed by picrate electrode. Advantages offered by this technique are the fast response, accuracy, precision, minimum interferences by many common ions