Method for preparing aqueous solution of high-concentration calcium phosphate stable in neutral pH range
Disclosed herein is a method for preparing an aqueous solution of high-concentration calcium phosphate, the method comprising the steps of: preparing an acidic aqueous solution using an acidic chelating agent; and dissolving a calcium phosphate-based compound in the acidic aqueous solution, and then adding a pH-adjusting agent to the acidic aqueous solution to adjust the pH of the acidic aqueous solution. The disclosed aqueous solution does not form a precipitate after neutralization so that it can be used in various calcium-containing products, including foods, drugs, or quasi-drugs.
1. A method for preparing an aqueous solution of high-concentration calcium phosphate, the method comprising the steps of:
preparing an acidic aqueous solution using an acidic chelating agent;
dissolving a calcium phosphate-based compound in the acidic aqueous solution to obtain an aqueous calcium phosphate solution; and
adding a pH-adjusting agent to the aqueous calcium phosphate solution increase the pH of the aqueous solution.
2. The method of claim 1 , wherein phosphoric acid (H 3 PO 4 ) is further added to the aqueous calcium phosphate solution.
3. The method of claim 1 , wherein the acidic chelating agent is any one selected from citric acid and EDTA (ethylene diamine tetra-acetic acid).
4. The method of claim 1 , wherein the calcium phosphate-based compound is at least one selected from the group of hydroxyapatite, carbonated apatite Ca 10 , tricalcium phosphate, and calcium hydrogen phosphate.
5. The method of claim 1 , wherein the pH-adjusting agent is at least one selected from sodium hydroxide and sodium hydrogen carbonate.
6. The method of claim 1 , wherein the acidic aqueous solution and the calcium phosphate-based compound are an aqueous citric acid solution and nano-sized carbonated apatite (n-CAP), respectively.
7. The method of claim 6 , wherein the citric acid and the n-CAP are used at concentrations of 0.3 wt % or less and 0.25 wt % or less, respectively, based on the total weight of the aqueous calcium phosphate solution.
8. The method of claim 6 , wherein the citric acid and the n-CAP are used at concentrations of 0.1 wt %, respectively, based on the total weight of the aqueous calcium phosphate solution.
9. The method of claim 1 , wherein the pH of the aqueous calcium phosphate solution is in the range from 5.5 to 6.1.
10. The method of claim 2 , wherein the phosphoric acid is added in an amount of 0.0012˜0.006 wt % based on the total weight of the aqueous calcium phosphate solution.
11. The method of claim 10 , wherein the phosphoric acid is added in an amount of 0.0024 wt % based on the total weight of the aqueous calcium phosphate solution.