Method and apparatus for determining liquid volume

• US 20070161114A1
• Filed: 01/06/2006
• Published: 07/12/2007
• Est. Priority Date: 01/06/2006
• Status: Active Grant

• Current Assignee: Artel Incorporated (Conagra Brands, Inc.)
• Original Assignee: Artel Incorporated (Conagra Brands, Inc.)
• Inventors: Ewing, Charles, McNally, Ceara, Curtis, Richard
• Granted Patent: US 7,772,008 B2
• Time in Patent Office: Days
• US Class Current: 436/164
• CPC Class Codes: G01F 22/00 Methods or apparatus for measuring volume of fluids or fluent solid material, not otherwise provided for
• CPC Class Codes: G01N 1/38 Diluting, dispersing or mixing samples
• CPC Class Codes: G01N 21/314 with comparison of measurements at specific and non-specific wavelengths dual wavelength spectrometry G01J3/427

Abstract

A method, apparatus and kit for precisely and accurately determining the volume of a liquid aliquot which can be used to calibrate a liquid delivery device. Two dye-containing solutions, a sample solution and a diluent solution, are prepared such that each solution contains a different dye, with the solutions having different absorbance values at a first wavelength and at a second wavelength. The absorbance value of a known volume of diluent solution is measured at both wavelengths. Either one aliquot of sample solution is added to the diluent solution and then absorbance measurements are made at both wavelengths, or multiple aliquots of sample solution are mixed serially into the diluent solution and then absorbance measurements are made at both wavelengths after each aliquot is added. The volume of any single aliquot is calculated by using a two-step formula which is based on the Beer-Lambert law.

Claims

1. A method for determining the volume of a liquid aliquot, comprising the steps of:

a. making a sample solution by adding a first dye to a solvent, the first dye having an extinction coefficient such that the sample solution has an absorbance value at a first wavelength which is different from an absorbance value at a second wavelength;

b. making a diluent solution by adding a second dye to a solvent, the second dye having an extinction coefficient such that the diluent solution has an absorbance value at the first wavelength which is different from an absorbance value at the second wavelength;

c. measuring the absorbance value of a known volume of the diluent solution at the first wavelength and at the second wavelength;

d. adding an aliquot of the sample solution to the known volume of diluent solution of step (c) to make a sample-diluent solution;

e. measuring the absorbance value of the sample-diluent solution of step (d) at the first wavelength and at the second wavelength; and

f. calculating the volume of the aliquot of the sample solution by using the absorbance values measured in step (c) and step (e).

2. The method of claim 1 wherein after step (e) is performed, steps (d) and (e) are repeated successively at least one more time before step (f) is performed at least one time.

3. The method of claim 1 wherein after step (f) is performed, steps (d)-(f) are repeated successively n times, where n is greater than or equal to 1.

4. The method of claim 1 wherein step (f) is performed by using computer-executable software stored on a computer-readable medium, the computer-executable software being capable of calculating volume of a liquid sample solution aliquot based upon absorbance values measured by using the method.

5. The method of claim 1 wherein step (f) includes the step of calculating total volume using the equation:

6. The method of claim 5 wherein step (f) further includes the step of calculating the aliquot volume using the equation:

7. The method of claim 1 wherein the temperature of the diluent solution of step (c) is measured before step (c) is performed, and the temperature of the sample-diluent solution is measured before step (e) is performed.

8. The method of claim 7 wherein the temperature of either or both of the diluent solution and the sample-diluent solution are used in the calculation in step (f).

9. An apparatus for determining the volume of a liquid aliquot, comprising:

a. a spectrophotometer;

b. a central processing unit coupled to the spectrophotometer; and

c. software stored on a computer-readable medium and executable on the central processing unit, the computer-executable software being capable of calculating volume of a liquid sample solution based upon absorbance values measured by carrying out a method, the method comprising the steps of;

i. making a sample solution by adding a first dye to a solvent, the first dye having an extinction coefficient such that the sample solution has an absorbance value at a first wavelength which is different from an absorbance value at a second wavelength;

ii. making a diluent solution by adding a second dye to a solvent, the second dye having an extinction coefficient such that the diluent solution has an absorbance value at the first wavelength which is different from an absorbance value at the second wavelength;

iii. measuring with the spectrophotometer the absorbance value of a known volume of the diluent solution at the first wavelength and at the second wavelength;

iv. adding an aliquot of the sample solution to the known volume of diluent solution of step (iii) to make a sample-diluent solution; and

v. measuring with the spectrophotometer the absorbance value of the sample-diluent solution at the first wavelength and at the second wavelength.

10. The apparatus of claim 9 wherein the absorbance values of step (iii) are measured while the diluent solution is contained in a cuvette.

11. The apparatus of claim 9 wherein the absorbance values of step (iii) are measured while the diluent solution is contained in a well of a multi-well plate.

12. The apparatus of claim 9 wherein the absorbance values of step (iii) are measured by a probe, which is connected to a spectrophotometer, while the probe is immersed in the diluent solution.

13. The apparatus of claim 9 wherein the absorbance values of step (iii) are measured while the diluent solution passes through a flow cell.

14. The apparatus of claim 9 wherein the absorbance values of step (v) are measured while the sample-diluent solution is contained in a cuvette.

15. The apparatus of claim 9 wherein the absorbance values of step (v) are measured while the sample-diluent solution is contained in a well of a multi-well plate.

16. The apparatus of claim 9 wherein the absorbance values of step (v) are measured by a probe, which is connected to a spectrophotometer, while the probe is immersed in the sample-diluent solution.

17. The apparatus of claim 9 wherein the absorbance values of step (v) are measured while the sample-diluent solution passes through a flow cell.

18. A kit for determining the volume of a liquid aliquot, comprising:

a. a known volume of a diluent solution, the diluent solution including a second dye in a solvent, the second dye having an extinction coefficient such that the diluent solution has an absorbance value at a first wavelength which is different from an absorbance value at a second wavelength; and

b. instructions for carrying out a method for determining the volume of a liquid aliquot, comprising the steps of;

i. making a sample solution by adding a first dye to a solvent, the first dye having an extinction coefficient such that the sample solution has an absorbance value at the first wavelength which is different from an absorbance value at the second wavelength;

ii. measuring absorbance value of the known volume of the diluent solution at the first wavelength and at the second wavelength;

iii. adding an aliquot of the sample solution to the known volume of diluent solution of step (ii) to make a sample-diluent solution;

iv. measuring the absorbance value of the sample-diluent solution at the first wavelength and at the second wavelength; and

v. calculating the volume of the aliquot of the sample solution by using the measured absorbance values obtained in step (ii) and step (iv).

19. The kit of claim 18 wherein the instructions instruct that after step (iv) is performed, steps (iii) and (iv) are repeated successively at least one more time before step (v) is performed at least one time.

20. The kit of claim 18 wherein the instructions instruct that after step (v) is performed, steps (iii)-(v) are repeated successively n times, wherein n is greater than or equal to 1.

21. The kit of claim 18 wherein the kit further includes the first dye.

22. The kit of claim 18 wherein the kit further includes more than one dye which may be used as the first dye.

23. The kit of claim 18 wherein the kit further includes the sample solution of step (i).

24. The kit of claim 18 wherein the known volume of diluent solution of step (ii) is added to a liquid holder and the liquid holder is sealed.

25. The kit of claim 18 wherein the kit further includes computer-executable software stored on a computer-readable medium, the computer-executable software being capable of calculating volume of a liquid sample solution based upon absorbance values measured by carrying out the method.

26. The kit of claim 18 wherein the second dye is dissolved in the solvent.

27. The kit of claim 18 wherein the second dye is not dissolved in the solvent.