Blood methemoglobin analysis

• US 6,194,218 B1
• Filed: 01/22/1999
• Issued: 02/27/2001
• Est. Priority Date: 01/22/1999
• Status: Expired due to Fees

• Current Assignee: The Fredric Rieders Family Renaissance Foundation
• Original Assignee: The Fredric Rieders Family Renaissance Foundation
• Inventors: Rieders, Fredric, Macherone, Anthony J.
• Primary Examiner(s): WALLENHORST, MAUREEN
• Application Number:
  US09/235,472
• Time in Patent Office: 767 Days
• Field of Search: 436/8, 436/15, 436/17, 436/18, 436/63, 436/66, 436/164, 436/166, 436/176, 252/408.1, 422/82.05, 422/82.09, 422/99, 422/102, 435/2
• US Class Current: 436/66
• CPC Class Codes: G01N 33/721 Haemoglobin
• CPC Class Codes: Y10T 436/10 Composition for standardization, calibration, simulation, stabilization, preparation or preservation; processes of use in preparation for chemical testing
• CPC Class Codes: Y10T 436/107497 Preparation composition [e.g., lysing or precipitation, etc.]
• CPC Class Codes: Y10T 436/108331 Preservative, buffer, anticoagulant or diluent
• CPC Class Codes: Y10T 436/2525 Stabilizing or preserving

Abstract

Blood samples are stabilized for methemoglobin determination with a buffer composition containing (a) carbon monoxide-containing water; (b) sodium tetraborate or potassium tetraborate; and (c) KCN or NaCN. The buffer composition preferably may also have an erythrocytolysis agent. The buffer fixes the valence state of heme iron at a concentration representative of the blood at the time of collection, and maintains that fixed state for an extended period of time preventing further methemoglobin formation. The buffer also prevents reduction of existing target analyte, i.e., methemoglobin (ferric hemoglobin, Fe³⁺ hemoglobin) to normal reduced hemoglobin (ferrous hemoglobin, Fe²⁺ hemoglobin).

Claims

1. A buffer composition for stabilizing blood samples for methemoglobin determination comprising:

(a) carbon monoxide-containing water;

(b) a tetraborate salt selected from the group consisting of sodium tetraborate, potassium tetraborate and combinations thereof; and

(c) a cyanide compound selected from the group consisting of KCN, NaCN and combinations thereof.

2. The composition according to claim 1 comprising, per deciliter of carbon monoxide-containing water, from about 2.5 to about 3.5 grams of the tetraborate salt and from about 1 to about 3 mg of the cyanide compound.

3. The composition according to claim 2 comprising, per deciliter of carbon monoxide-containing water, from about 2.9 to about 3.1 grams of the tetraborate salt and from about 1.8 to about 2.2 mg of the cyanide compound.

4. The composition according to claim 1 further comprising an erythrocytolysis agent.

5. The composition according to claim 4 comprising, per deciliter of carbon monoxide-containing water, from about 40 to about 100 microliters of the erythrocytolysis agent.

6. A combination comprising a resealable spectrophotometer cuvette suitable for conducting spectrophotometric analysis over the wavelength range 500 nm to 650 nm and a volume of the buffer composition of claim 4 contained in said cuvette.

7. A buffered blood preparation comprising a blood sample and an amount of a buffer composition according to claim 4 sufficient to substantially convert methemoglobin in the blood sample to cyanmethemoglobin.

8. The composition according to claim 1 wherein the cyanide compound is KCN and the tetraborate salt is sodium tetraborate.

9. The composition according to claim 8 containing an erythrocytolysis agent which is octylphenoxy polyethoxy ethanol.

10. The composition according to claim 9 wherein the carbon monoxide-containing water is saturated with carbon monoxide.

11. The composition according to claim 10 comprising, per deciliter of carbon monoxide-saturated water, from about 2.5 to about 3.5 grams sodium tetraborate, from about 1 to about 3 mg KCN, and from about 0.002 to about 0.023 ml octylphenoxy polyethoxy ethanol.

12. A combination comprising a resealable spectrophotometer cuvette suitable for conducting spectrophotometric analysis over the wavelength range 500 nm to 650 nm and a volume of the buffer composition of claim 11 contained in said cuvette.

13. A buffered blood preparation comprising a blood sample and an amount of a buffer composition according to claim 11 sufficient to substantially convert methemoglobin in the blood sample to cyanmethemoglobin.

14. A combination comprising a resealable spectrophotometer cuvette suitable for conducting spectrophotometric analysis over the wavelength range 500 nm to 650 nm and a volume of the buffer composition of claim 8 contained in said cuvette.

15. A buffered blood preparation comprising a blood sample and an amount of a buffer composition according to claim 8 sufficient to substantially convert methemoglobin in the blood sample to cyanmethemoglobin.

16. A combination comprising a resealable spectrophotometer cuvette suitable for conducting spectrophotometric analysis over the wavelength range 500 nm to 650 nm and a volume of the buffer composition of claim 1 contained in said cuvette.

17. A buffered blood preparation comprising a blood sample and an amount of a buffer composition according to claim 1 sufficient to substantially convert methemoglobin in the blood sample to cyanmethemoglobin.

18. A method for preparing a buffer composition for stabilizing blood samples for methemoglobin determination comprising dissolving in carbon monoxide-containing water:

(a) a tetraborate salt selected from the group consisting of sodium tetraborate, potassium tetraborate and combinations thereof; and

(b) a cyanide compound selected from the group consisting of KCN, NaCN and combinations thereof.

19. The method according to claim 18 comprising dissolving in the carbon monoxide-containing water, per deciliter of said water, from about 2.5 to about 3.5 grams of the tetraborate salt and from about 1 to about 3 mg of the cyanide compound.

20. The method according to claim 18 wherein the carbon monoxide-containing water is carbon monoxide-saturated water.

21. The method according to claim 18 further comprising dissolving an erythrocytolysis agent in the carbon monoxide-containing water.

22. The method according to claim 21 wherein the erythrocytolysis agent is octylphenoxy polyethoxy ethanol.

23. A method of stabilizing blood for determination of methemoglobin content comprising treating said blood with a carbon monoxide-saturated water solution providing cyanide ions in an amount sufficient to substantially convert any methemoglobin in the blood to cyanmethemoglobin, said solution further containing a tetraborate salt selected from the group consisting of sodium tetraborate, potassium tetraborate and combinations thereof.

24. The method of claim 23 wherein said cyanide ions are provided by a cyanide compound selected from the group consisting of KCN, NaCN and combinations thereof.

25. The method of claim 24 wherein the solution comprises, per deciliter of carbon monoxide-saturated water, from about 2.5 to about 3.5 grams of the tetraborate salt and from about 1 to about 3 mg of the cyanide compound.

26. The method of claim 25 wherein the solution further comprises an erythrocytolysis agent.

27. The method of claim 26 wherein the cyanide compound is KCN, the tetraborate salt is sodium tetraborate, and the erythrocytolysis agent is octylphenoxy polyethoxy ethanol.