Speciation of AlIII in blood serum - The AlIII-citrate-phosphate ternary system

Andrea Lakatos, Ferenc Evanics, György Dombi, Roberta Bertani, Tamás Kiss

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Time-dependent speciation studies have been carried out on the ternary AlIII-citrate (A)-phosphate (B) system in order to clarify the solution state of AlIII in blood serum. The potentiometric results indicate that ternary complexes predominate both in freshly prepared mixtures and at equilibrium. The ternary species AlAB and AlABH-1 and the binary species AlAH-1 and AlBH-1 are present at physiological pH. As the solution ages the amount of the trinuclear species [Al3(AH-1)3(OH)]4- increases at the expense of the mononuclear binary and ternary complexes. 31P NMR spectra measured at neutral pH provide corroborating evidence of the formation of the ternary complexes AlAB and AlABH-1 and binary species AlBH-1 and Al2BH-3 found potentiometrically. Time-dependent 1H NMR measurements show that monodentate phosphate can slowly displace citrate from the otherwise very stable structure of the trinuclear species [Al3(AH-1)3(OH)]4-. At blood serum concentrations [c(AlIII) = 3 μM], AlIII is mostly bound to citrate either in binary species or in the ternary species formed with phosphate. However, with increasing AlIII concentrations binding to phosphate becomes more important.

Original languageEnglish
Pages (from-to)3079-3086
Number of pages8
JournalEuropean Journal of Inorganic Chemistry
Issue number12
Publication statusPublished - Jan 1 2001



  • Aluminium
  • Bioinorganic chemistry
  • Citric acid
  • Inorganic phosphate
  • NMR spectroscopy
  • Speciation of blood serum

ASJC Scopus subject areas

  • Inorganic Chemistry

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