Colloids and Surfaces
A: Physicochemical and Engineering Aspects 170 (2000) 107 – 112
Controversy about -tricalcium phosphate
M. Tonkovic ´ *, M. Sikiric ´
1
, V. Babic ´-Ivanc ˇic ´
Department of Chemistry, Rudjer Bos ˇkoic ´ Institute, Bijenic ˇka 54, 10000 Zagreb, Croatia
Received 4 June 1999; accepted 28 January 2000
Abstract
The calcium phosphate which corresponds to the formula Ca
3
(PO)
4
· n H
2
O (2 n 3) was isolated from solutions
with Ca/P molar ratio 0.2 and pH 7. The compound was characterised by chemical and thermogravimetric analyses,
Fourier-transform infrared (FTIR) spectroscopy and X-ray diffraction. The FTIR spectra were compared with
spectra of -tricalcium phosphate (-TCP) in the atlases for analysis of urinary calculi and other literature data.
© 2000 Elsevier Science B.V. All rights reserved.
Keywords: Tricalcium phosphate hydrate; -Tricalcium phosphate; Urinary calculi; Fourier-transform infrared; X-ray diffraction
www.elsevier.nl/locate/colsurfa
1. Introduction
Accurate knowledge of the composition of hu-
man urinary calculi is essential to the study of
their formation and the choice of medical treat-
ments. The determination of urinary calculi com-
position is usually made by the infrared (IR)
spectroscopy or X-ray diffraction (XRD), which
are considered the most rapid and reliable analyt-
ical methods for this purpose.
Various calcium phosphates were identified as
either major or minor components of human uri-
nary calculi. Because of their physiological rele-
vance, the formation and transformation
behaviour of these compounds has been exten-
sively studied. It has been shown that the types of
calcium phosphate precipitate are influenced by
the various factors such as pH, temperature, ionic
concentration, Ca/P molar ratio, rate of stirring
and digestion time. Under conditions of high su-
persaturation the initial Ca/P molar ratio of the
solution has no significant effect on the type
Ca-phosphate formed, whereas under conditions
of low supersaturation the initial Ca/P molar ratio
of the solution exerts an influence. Among all
calcium phosphates, the carbonate apatite
Ca
10
(PO
4
)(CO
3
OH)
6
(OH)
2
and calcium hydrogen
phosphate dihydrate CaHPO
4
· 2H
2
O (DCPD,
brushite) are considered the frequent urinary cal-
culi substances; -tricalcium phosphate Ca
3
(PO
4
)
2
(-TCP, whitlockite) and amorphous calcium
phosphate Ca
3
(PO
4
)
2
as rare urinary calculi
substances and calcium hydrogen phosphate
CaHPO
4
(monetite), octa calcium phosphate
* Corresponding author. Tel.: +385-1-4561007; fax: +385-
1-4680245.
E-mail address: tonkovic@rudjer.irb.hr (M. Tonkovic ´)
1
Present address: Faculty of Agriculture, University of Za-
greb, Zagreb, Croatia.
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