title: Increasing the sensitivity of the spectrophotometric determinations of the oxygen content in YBCO superconducting samples using the I(3-)-starch compound.
abstract: The conditions for formation of the I(3)(-)-starch compound and measuring its absorbance have been found, and a spectrophotometric method has been developed for the determination of the oxygen content in YBa(2)Cu(3)O(y) superconducting bulk samples. The method involves the following stages: a decomposition of the sample in an acid medium in the presence of iodide ions under inert atmosphere; formation of a complex between Cu(II) and glycine; binding the I(3)(-)-complex with a starch and the absorbance measurement of the colored I(3)(-)-starch compound. The coefficient of the active oxygen is calculated by the ratio of the absorbances of two solutions and the method does not require both calibration and precise measuring sample mass. The accuracy of the results is confirmed applying the comparative spectrophotometric method that uses the yellow I(3)(-)-complex. The precision of the results evaluated by the relative standard deviation is 2%. The developed method is sensitive and allows a sample mass about 2mg to be used. The analysis is rapid and requires a simple and inexpensive apparatus. Thus the new method would be useful for an express analytical control of the oxygen content of YBCO-superconducting materials produced for the electronics.
authors.affiliation: Department of Analytical Chemistry, University of Chemical Technology and Metallurgy, Kl. Ohridski 8, 1756 Sofia, Bulgaria.
authors.forename: Tsvetanka K
authors.initials: TK
authors.lastname: Nedeltcheva
authors.forename: Stela Iv
authors.initials: SI
authors.lastname: Georgieva
authors.forename: Latinka K
authors.initials: LK
authors.lastname: Vladimirova
authors.forename: Angelina K
authors.initials: AK
authors.lastname: Stoyanova-Ivanova