Apatite Formation: Why It May Not Work as Planned, and How to Conclusively Identify Apatite Compounds

Table 1

Chemical composition of blood plasma (inorganic species) from Krebs [25], at pH 7.4 and 37°C, and speciation data (calculated using the Visual Minteq 3.0 software).

Main ion types	Average global concentration (mM)	Main species (and % of total concentration*)	Corresponding activities** (mM)
Sodium	137.4	Na^+ (97%)	100.900
Chloride	103	Cl^− (96%)	75.427
Carbonate	27	HCO3^− (90%)	18.509
		H2CO3(aq) (5%)	1.486
Potassium	4.4	K^+ (97%)	3.246
Calcium	2.5	Ca^2+ (79%)	0.655
		CaHCO3^+ (9%)	0.177
		CaCl^+ (7%)	0.132
Phosphate (inorganic)	1	HPO4^2− (45%)	0.151
		NaHPO4^− (30%)	0.226
		H2PO4^− (12%)	0.090
		CaHPO4(aq) (5%)	0.054
Magnesium	0.8	Mg^2+ (78%)	0.207
		MgCl^+ (11%)	0.066
		MgHCO3^+ (7%)	0.042
Sulfate (inorganic)	0.5	SO4^2− (75%)	0.125
		NaSO4^− (19%)	0.071

*For species in amount ≥5%.
**Using Davies’ equation for calculation of activity coefficients (total ionic strength ~0.14 M).