development of carbon paste sensor for low level and selective determination of ondansetron in pharmaceutical and biological samples

Abstract: ondansetron (or zofran, or demitron), (rs)-9-methyl-3-[(2-methyl-1h-imidazol-1-yl) methyl] 2,3-dihydro-1h-carbazol-4(9h)-one, is a highly selective and potent 5-hydroxytryptamine type 3 (5-ht3) receptor antagonist. it is effective in the treatment of nausea and vomiting during cancer chemotherapy and radiotherapy, and has reported anxiolytic and neuroleptic properties. 5ht released by chemotherapy, radiotherapy and surgery also activates the 5ht3 receptors that are found in the ctz in the brain, causing further messages to be sent to the vomiting center. ondansetron works by blocking the 5ht3 receptors that are found in the brain and gut [1]. a few methods have been used for quantitative determination of ondansetron including hplc [2], voltammetry [3], spectrophotometry [4] and potentiometry [5]. the reported potentiometric sensor was the liquid membrane electrode, while, no carbon paste potentiometric sensor for this drug has been reported so far. in this study, performance characteristics of a new potentiometric carbon paste electrode (cpe) for the fast, easy and selective determination of ondansetron was described. the constructed potentiometric sensor was based on the use of the 2-hydroxypropyl-β-cyclodextrin as a good ionophore in the carbon paste matrix. the resulted modified cpe exhibited nernstian slope of 59.8 mv/decade over a wide concentration range of 1.5×10-9 – 1.3×10-6 m with low detection limit of 8.4×10-9 m. the potentiometric response of the electrode was studied in buffered solution. the proposed sensor manifested advantages of high stability, fast response, long life time and, most importantly, good selectivities for ondansetron relative to a wide variety of common foreign inorganic and biological species. the influence of temperature on the potential response of the sensor was tested at different temperature and the temperature coefficient of the sensor was calculated. the sensor was successfully applied as an indicator electrode in potentiometric determination of ondansetron in ondansetron tablet and blood serum samples.