Inhibition of precipitation of carbonate apatite by trisodium citrate analysed in base of the formation of chemical complexes in growth solution

• Trisodium citrate (TC) increases induction time of carbonate apatite (CA) formation.
• TC decreases the efficiency of CA precipitation.
• The inhibitory effect of TC is explained in base of chemical speciation analysis.
• The inhibitory effect is mainly related with the fact that TC binds Ca2+ ions.
• TC binds Ca2+ ions in the range of pH from 6 to 9.5 for which CA is formed.

Effect of trisodium citrate on the precipitation of carbonate apatite is studied. The experimental series are performed in the solution of artificial urine. The investigations are related to infectious urinary stones formation as carbonate apatite is one of the main components of this kind of stones. To mimic a real infection in urinary tract the aqueous ammonia solution was added to the solution of artificial urine. The spectrophotometric results demonstrate that trisodium citrate increases induction time with respect to carbonate apatite formation and decreases the efficiency of carbonate apatite precipitation. The inhibitory effect of trisodium citrate on the precipitation of carbonate apatite is explained in base of chemical speciation analysis. Such an analysis demonstrates that the inhibitory effect is mainly related with the fact that trisodium citrate binds Ca2+ ions and causes the formation of CaCit− and Ca10(PO4)6CO3 complexes. Trisodium citrate binds Ca2+ ions in the range of pH from 6 to 9.5 for which carbonate apatite is favored to be formed.

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