Method for quantitatively determining unbound metal in formulations containing chelates
View Patent ↗Methods are provided for quantitatively determining the amount of unbound metal present in a sample suspected of containing a metal-ligand chelate.
1. A method for assaying an amount of unbound metal in a liquid sample containing a metal-ligand chelate, comprising:
contacting the sample with a liquid carrier;
eluting the sample and liquid carrier through an ion chromatography column to produce an eluent;
determining the amount of unbound metal in the eluent.
2. The method according to claim 1 , wherein the amount of unbound metal in the eluent is determined by a spectroscopic method.
3. The method of claim 1 , wherein the amount of unbound metal in the eluent is determined by a non-spectroscopic method.
4. The method of claim 1 , wherein the amount of unbound metal in the eluent is determined by atomic absorption spectroscopy, inductively coupled plasma techniques, ISE, titrations, conductivity, UV-Vis, fluorescence detection, PDA (photo diode array) or mass spectroscopy.
5. The method according to claim 1 , wherein the liquid carrier includes a buffer solution.
6. The method according to claim 1 , wherein the liquid carrier has a pH of from about 2 to about 10.
7. The method according to claim 1 , wherein the ion chromatography column includes a styrene divinyl benzene base material with sulfite residues.
8. A method for assaying an amount of unbound metal in a liquid sample suspected of containing a metal-ligand chelate, comprising:
contacting the sample with a liquid carrier;
eluting the sample and liquid carrier through an ion chromatography column to produce an eluent;
determining the amount of unbound metal in the eluent;
wherein the metal is selected from the group consisting of: boron, calcium, chromium, cobalt, copper, iron, magnesium, manganese, potassium, selenium, vanadium and zinc; and
wherein the ligand is selected from the group consisting of: alanine, arginine, asparagine, aspartic acid, cysteine, glutamic acid, glutamine, glycine, histidine, isoleucine, leucine, lysine, methionine, phenylalanine, proline, serine, threonine, tryptophan, tyrosine and valine.
9. The method according to claim 8 , wherein the amount of unbound metal in the eluent is determined by a spectroscopic method.
10. The method of claim 8 , wherein the amount of unbound metal in the eluent is determined by a non-spectroscopic method.
11. The method of claim 8 , wherein the amount of unbound metal in the eluent is determined by atomic absorption spectroscopy, inductively coupled plasma techniques, ISE, titrations, conductivity, UV-Vis, fluorescence detection, PDA (photo diode array) or mass spectroscopy.
12. The method according to claim 8 , wherein the liquid carrier includes a buffer solution.
13. The method according to claim 8 , wherein the liquid carrier has a pH of from about 2 to about 10.
14. The method according to claim 8 , wherein the metal is selected from boron and selenium.
15. The method according to claim 8 , wherein the metal is selected from calcium and magnesium.
16. The method according to claim 8 , wherein the metal is selected from chromium, cobalt, copper, iron, manganese, vanadium, and zinc.
17. The method according to claim 8 , wherein the metal is selected from potassium.