| Budget Amount *help |
¥3,600,000 (Direct Cost: ¥3,600,000)
Fiscal Year 2005: ¥1,600,000 (Direct Cost: ¥1,600,000)
Fiscal Year 2004: ¥2,000,000 (Direct Cost: ¥2,000,000)
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| Research Abstract |
A combined pre- and on-column capillary electrophoretic (CE) method was developed for the simultaneous determination of In(III) and Ga(III) at trace levels. Prior to CE analysis, Mo(VI) was added to a mixture of In(III) and Ga(III), to form the so-called Anderson-type [GaMo_6O_<24>H_6]^<3-> complex. When the sample solution was introduced into the capillary filled with 0.05 M monochloroacetate buffer (pH 2.5) containing [PW_<11>O_<39>]^<7->, In(III) was immediately complexed with [PW_<11>O_<39>]^<7-> to form the ternary Keggin-type complex, [P(In^<III>W_<11>O_<40>]^<6->. Since the [GaMo_6O_<24>H_6]^<3-> and [P(In^<III>W_<11>)O_<40>]^<6-> complexes possessed different electrophoretic mobilities, Ga(III) and In(III) are determined simultaneously. Trace amounts of Sc(III) and Y(III) can react with [PW_<11>O_<39>]^<7-> to form the ternary Keggin-type complexes ; [P(Sc^<III>W_<11>)O_<40>]^<6-> and [P(Y^<III>W_<11>)O_<40>]^<6-> having high molar absorptivities. The complex-formation reaction
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was applied to the simultaneous CE determination of Sc(III) and Y(III). The formation process of the α- and β-Keggin-type [PW_<12>O_<40>]^<3-> complexes was investigated in an aqueous 50 mM W(VI)-5.0 mM P(V) system. The ^<31>P NMR study confirmed the formation of A-α-[PW_9O_<34>]^<9->, A-β-[PW_9O_<34>]^<9->, α-[[PW_<11>O_<39>]^<7->, and β_1-[PW_<11>O_<39>]^<7-> on acidification of an alkaline solution of WO_4^<2-> and HPO_4^<2-> to pH 7.5 or below. A mixture of α- and β-[PW_<12>O_<40>]^<3-> was obtained on further acidification of such solutions containing both α- and β-type lacunary complexes to pH 1 or below. Heating of the W(VI)-P(V) system caused A-α-[PW_9O_<34>]^<9->, A-β-[PW_9O_<34>]^<9->, and β_1-[PW_<11>O_<39>]^<7-> to disappear completely, leaving α-[PW_<11>O_<39>]^<7->, and acidification of the α-[PW_<11>O_<39>]^<7-> solution produced only α-[PW_<12>O_<40>]^<3->. For Keggin-type polyoxometalate complexes, the conversion processes of the first two one-electron waves into a two-electron wave were investigated in dipolar aprotic solvents containing H^+,Li^+, or Na^+ as a Lewis acid. The voltammetric properties of the Keggin anions were systematized with reference to their basicities. Less
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