^<27>Al及び^<31>P核磁気共鳴法による水溶液中のアルミニウム-クエン酸-リン酸三元錯体の検出

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In order to confirm the formation of ternary aluminum-citrate-phosphate complexes, which have been predicted by a potentiometric study on the reaction between aluminum ion, citrate and phosphate in aqueous solution, ^<27>Al and ^<31>P NMR spectra for solutions containing aluminum ion (Al) citrate (L) and phosphate (P) {Al:L:P mole ratio=1:1:n (n=0〜5)} at pH 3.0 and 4.0 were measured. In a solution of pH 3.0 with Al: L=1:1 in the absence of P, a mononuclear Al-L complex in addition to [Al(H_2O)_6]^<3+> existed, while in a solution with Al:L:P=1:1:1 of the same pH, the formation of a ternary complex (P-Al-L) was confirmed by Al and ^<31>P NMR measurements. The broad ^<27>Al and ^<31>P NMR peaks assigned to the P-Al-L were observed around 0 ppm and -4.8 ppm, respectively. The intensity of both peaks increased with increasing the proportion of P. In a solution with the same composition of pH 4.0, the formation of a trinuclear complex, (Al_3-L_3), the major species in the solution with Al:L=1:1 in the absence of P, was prevented due to the predominant formation of the P-Al-L.
社団法人日本分析化学会の論文
2007-03-05