Spectrophotometric Determination of Cerium (III) with Arsenazo III: Application to Sea Water and Synthetic Alloys

Abstract

The detailed investigation of a sensitive and selective spectrophotometric method for the determination of trace amounts of cerium is described. The method is based on the reaction of cerium(III) with arsenazo ш in the presence of sodium dodecyl sulphate surfactant at pH 3.0 to form a blue-greenish coloured chelate absorbing maximum at 653 nm. Beer's law is obeyed over the range (5-70) µg /25 ml, with a molar absorptivity of (4.99×10 4) l.mol-1 .cm-1 and the coefficient of determination (r 2) is 0.9994, Sandell ' s sensitivity index is (28.08×10-4) µg.cm-2 , a relative error of (0.0-0.2%) and a relative standard deviation of (0.0 to +2.1)%, depending on the concentration levels in the calibration curve. The method has been applied successfully to determine cerium in sea water and some synthetic alloys. ‫ــــــــــــــــــــــــــــــــــــــــــــــــــــ‬ ‫ﺍﻟﺜﻼﺜ‬ ‫ﻟﻠﺴﻴﺭﻴﻭﻡ‬ ‫ﺍﻟﻁﻴﻔﻲ‬ ‫ﺍﻟﺘﻘﺩﻴﺭ‬ ‫ﺒ‬ ‫ﻲ‬ ‫ﺍﺭﺴﻴﻥ‬ ‫ﻜﺎﺸﻑ‬ ‫ﺁ‬ ‫ﺯﻭ‬-‫ﺍﻟﺒﺤﺭ‬ ‫ﻤﺎﺀ‬ ‫ﻋﻠﻰ‬ ‫ﺍﻟﺘﻁﺒﻴﻕ‬ ‫ﺍﻟﻤﺼﻨﻌﺔ‬ ‫ﻭﺍﻟﺴﺒﺎﺌﻙ‬ ‫ﺍﻟﻤﻠﺨﺹ‬ ‫ﺘﻁﻭﻴﺭ‬ ‫ﺘﻡ‬ ‫ﻟﻘﺩ‬ ‫ﺍﻟﺴﻴﺭﻴﻭﻡ‬ ‫ﺍﻴﻭﻥ‬ ‫ﻤﻥ‬ ‫ﺍﻟﺼﻐﺭ‬ ‫ﻓﻲ‬ ‫ﻤﺘﻨﺎﻫﻴﺔ‬ ‫ﻜﻤﻴﺎﺕ‬ ‫ﻟﺘﻘﺩﻴﺭ‬ ‫ﻭﺍﻨﺘﻘﺎﺌﻴﺔ‬ ‫ﺤﺴﺎﺴﺔ‬ ‫ﻁﻴﻔﻴﺔ‬ ‫ﻁﺭﻴﻘﺔ‬ ‫ﺒﻭﺠﻭﺩ‬ ‫ﺍﻟﺜﻼﺜﻲ‬ ‫ﺍﺯﻭ‬ ‫ﺍﻻﺭﺴﻴﻥ‬ ‫ﻜﺎﺸﻑ‬ ‫ﻤﻊ‬ ‫ﺍﻟﺜﻼﺜﻲ‬ ‫ﺍﻟﺩ‬ ‫ﺍﻟﺼﻭﺩﻴﻭﻡ‬ ‫ﻜﺒﺭﻴﺘﺎﺕ‬ ‫ﻭﺩ‬ ‫ﺤﺎﻤﻀﻴﺔ‬ ‫ﺩﺍﻟﺔ‬ ‫ﻋﻨﺩ‬ ‫ﻴﻜﺎﻟﻴﺔ‬ 3.0 ‫ﻟﺘﻜﻭﻴﻥ‬ ‫ﻤﻌﻘﺩ‬ ‫ﻤﺨﻠﺒﻲ‬ ‫ﻴﻌﻁﻲ‬ ‫ﺍﻟﺫﻱ‬ ‫ﺍﻟﻤﺎﺌﻲ‬ ‫ﺍﻟﻭﺴﻁ‬ ‫ﻓﻲ‬ ‫ﻤﺨﻀﺭ‬ ‫ﺍﺯﺭﻕ‬ ‫ﺃ‬ ‫ﺍﻟﻤﻭﺠﻲ‬ ‫ﺍﻟﻁﻭل‬ ‫ﻋﻨﺩ‬ ‫ﺍﻤﺘﺼﺎﺹ‬ ‫ﺸﺩﺓ‬ ‫ﻋﻠﻰ‬ 653 ‫ﻨﺎﻨﻭﻤﻴﺘﺭ‬. ‫ﺍﻟﺘﺭﻜﻴﺯ‬ ‫ﻤﺩﻯ‬ ‫ﻓﻲ‬ ‫ﺒﻴﺭ‬ ‫ﻗﺎﻨﻭﻥ‬ ‫ﺤﺩﻭﺩ‬ ‫ﻭﻜﺎﻨﺕ‬) 5-70 (‫ﺍﻟﻨﻬﺎﺌﻲ‬ ‫ﺍﻟﺘﻔﺎﻋل‬ ‫ﺤﺠﻡ‬ ‫ﻓﻲ‬ ‫ﻤﺎﻴﻜﺭﻭﻏﺭﺍﻡ‬ 25 ‫ﻤﻠﻠﺘﺭ‬ ‫ﻭﻜﺎﻨﺕ‬ ‫ﺍﻟﻤﻭﻻﺭﻴﺔ‬ ‫ﺍﻻﻤﺘﺼﺎﺼﻴﺔ‬ (10 4 ×4.99) ‫ﻟﺘﺭ‬. ‫ﻤﻭل‬-1. ‫ﺴﻡ‬-1 ‫ﻭﻗﻴﻤﺔ‬ ‫ﻤﻌﺎﻤل‬ ‫ﺍﻟﺘﻘﺩﻴﺭ‬ ‫ﺘﺴﺎﻭﻱ‬ 0.9994 ‫ﻭﺒﻠﻐﺕ‬ ‫ﻟﻠﺤﺴﺎﺴﻴﺔ‬ ‫ﺴﺎﻨﺩل‬ ‫ﺩﻻﻟﺔ‬) (10-4 ×28.08 ‫ﻤﺎﻴﻜﺭﻭ‬ ‫ﻏﺭﺍﻡ‬. ‫ﺴﻡ‬-2 ‫ﻨﺴﺒ‬ ‫ﻭﺒﺨﻁﺄ‬ ‫ﺒﻴ‬ ‫ﻲ‬ ‫ﻥ‬) 0-.2 0 %(‫ﻗﻴﺎﺴﻲ‬ ‫ﻭﺍﻨﺤﺭﺍﻑ‬ ‫ﺒﻴﻥ‬) 0-2.1 %(+ ‫ﺍﻟﻤﻌﺎﻴﺭﺓ‬ ‫ﻟﻤﻨﺤﻨﻲ‬ ‫ﺍﻟﺘﺭﻜﻴﺯ‬ ‫ﻤﺴﺘﻭﻴﺎﺕ‬ ‫ﻋﻠﻰ‬ ‫ﺒﺎﻻﻋﺘﻤﺎﺩ‬. ‫ﻭ‬ ‫ﺍﻟﺴﻴﺭﻴﻭﻡ‬ ‫ﻟﺘﻘﺩﻴﺭ‬ ‫ﺒﻨﺠﺎﺡ‬ ‫ﺍﻟﻁﺭﻴﻘﺔ‬ ‫ﻁﺒﻘﺕ‬ ‫ﻓﻲ‬ ‫ﺍﻟﺜﻼﺜﻲ‬ ‫ﺒﻌﺽ‬ ‫ﺍﻟﺒﺤﺭ‬ ‫ﻭﻤﺎﺀ‬ ‫ﺍﻟﻤﺼﻨﻌﺔ‬ ‫ﺍﻟﺴﺒﺎﺌﻙ‬. ‫ــــــــــــــــــــــــــــــــــــــــــــــــــــ‬