Graphite Electrode Coated with a 7,16‐Dibenzyl‐1,4,10,13‐tetraoxa‐7,16‐diazacyclooctadecane‐Multiwalled Carbon Nanotube Composite as Sensor For Detection of Samarium

Abstract

A composite multiwalled carbon nanotube polyvinyl chloride electrode based on 7, 4,10, Recently, a new generation of potentiometric solid-contact ion selective electrodes [1] has achieved high selectivities and a very low limit of detection [2] which makes them comparable to other more costly analysis techniques. Solid-contact electrodes are regarded as the potentiometric sensors of the future since they can be miniaturized and fabricated using the well-known thick and thin-film technologies [3]. Very recently, different carbonbased nanostructured materials such as three-dimensionally ordered macroporous carbon [4] and fullerenes [5] have been used as solid contact transducers in ISE [6].Multiwalled carbon nanotubes (MWNT) have very interesting physicochemical properties, such as ordered structure with high aspect ratio, ultralight weight, high mechanical strength, high electrical conductivity, high thermal conductivity, metallic or semi-metallic behavior, and high surface area [7]. The facile electron transfer between the electroactive species and the electrodes offers great promise for fabrication of electrochemical sensors and biosensors.The 4f elements are widely distributed in low concentration through out the earths crust [8]. However, the vapors or dust of these elements are known to be very toxic when inhaled and tend to remain in lungs, liver, spleen and kidneys. Samarium, one of the 4f elements, is used as a gasoline cracking catalyst and in the iron and steel industries to remove sulfur, carbon and other electronegative elements from iron and steel [9]. The potentiometric ion selective electrodes have become an emerging area of portable devices for trace level analysis of samarium.Various compounds described for preparation of Sm ,5,6,7-tetratiocino[1,2-b:3,4-b]diimidazolyl-1,3,8,10-tetraethyl-2,9-dithione [21] have also been reported. Many of these sensors, however, suffer from some disadvantages like narrow range of response, interference from associated anions and cations, the need for several time consuming steps for ionophore preparation, short life time of electrode etc.In our earlier work we developed coated wire membrane electrodes for certain metal ions viz. It is reported that Sm 3 + forms a strong complex (log K = 8.23) with 18C6 [27]. This crown ether also forms complex with other alkali and alkaline earth metal ions,