Calibrating dispensing device performance for complex and/or non-aqueous liquids

• US 8,003,405 B2
• Filed: 12/16/2005
• Issued: 08/23/2011
• Est. Priority Date: 12/16/2005
• Status: Active Grant

• Current Assignee: Artel Incorporated (Conagra Brands, Inc.)
• Original Assignee: Artel Incorporated (Conagra Brands, Inc.)
• Inventors: Bradshaw, John Thomas, Rogers, Alex L., Albert, Keith J.
• Primary Examiner(s): Warden; Jill
• Assistant Examiner(s): CHAN, CEDRIC A
• Application Number:
  US11/305,301
• Publication Number:
  US 20070141709A1
• Time in Patent Office: 2,076 Days
• Field of Search: 422 55- 57, 422/68.1, 422 8205- 8208, 422/82.09, 422/82.11, 73/17.3, 731/49, 738/61, 738/610.4, 738/610.7, 356/627, 356/408, 356/409, 356/425, 436/164, 436/166, 436/174, 436/179
• US Class Current: 436/174
• CPC Class Codes: G01F 25/0092 for metering by volume
• CPC Class Codes: G01N 1/38 Diluting, dispersing or mixing samples
• CPC Class Codes: G01N 21/25 Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
• CPC Class Codes: G01N 35/1016 Control of the volume dispensed or introduced
• 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 436/25 including sample preparation
• CPC Class Codes: Y10T 436/25625 Dilution

Abstract

A method for determining the volume of a test liquid aliquot used to calibrate a liquid delivery device. The method is useful for determining the volume of an aliquot of a test liquid which is complex, non-aqueous or both. A mixture contains the test liquid and a stock solution including a first dye, the first dye having absorbance characteristics which are measurably distinguishable from the absorbance characteristics of a second dye. The mixture is mixed with a diluent including the second dye to form a sample solution used to measure absorbances of the first dye and the second dye. The test liquid and the stock solution are combined gravimetrically in a controlled ratio so that the flow characteristics of the test-stock mixture correspond to the flow characteristics of the test liquid and without affecting the ability to distinguish the absorbance characteristics between the first dye and the second dye.

Claims

1. A method to create a test-stock mixture to be used in the determination of a volume of the test-stock mixture to be dispensed from a liquid handling device to be calibrated, the test-stock mixture including a test liquid of interest, the method comprising the step of mixing the test liquid with a stock solution, which stock solution includes a first dye with a known absorbance characteristic to form the test-stock mixture, wherein a ratio of test liquid to stock solution is selected to establish for the test-stock mixture flow characteristics that correspond to flow characteristics of the test liquid before mixing with the stock solution while maintaining in the test-stock mixture a distinction between the known absorbance characteristic of the first dye in the stock solution and a known absorbance characteristic of a second dye.

2. The method of claim 1 wherein the step of mixing includes the step of mixing the test liquid and the stock solution in a weight ratio as a function of the density of the stock solution and the density of the test liquid.

3. The method of claim 1 further comprising the step of calculating a dilution ratio of the stock solution by the test liquid in the test-stock mixture.

4. The method of claim 3 further comprising the step of determining a z-correction factor for fluctuations in density values of the test liquid and the stock solution.

5. The method of claim 1 wherein the stock solution includes the second dye.

6. The method of claim 1 wherein the known absorbance characteristic of the first dye of the stock solution includes an absorbance per pathlength of the first dye, the method further comprising the step of determining a revised absorbance per pathlength of the first dye in the test-stock mixture.

7. The method of claim 1 wherein the known absorbance characteristic of the second dye includes an absorbance per pathlength of the second dye, the method further comprising the step of determining a revised absorbance per pathlength of the second dye in the test-stock mixture.

8. A method for determining the volume of a liquid aliquot to be dispensed from a handling device, comprising the steps of:

a. making a test-stock mixture by mixing a test liquid having a known weight and a known density value with a stock solution having a known weight and a known density value, the stock solution including a first dye with a known absorbance characteristic;

b. adding an aliquot of the test-stock mixture to a liquid holder;

c. adding a diluent to the test-stock mixture in the liquid holder to produce a sample solution, the diluent including only a second dye having a known absorbance characteristic different from the known absorbance characteristic of the first dye, wherein a ratio of the known weight of the test liquid to the known weight of the stock solution is selected to establish for the test-stock mixture flow characteristics that correspond to flow characteristics of the test liquid before mixing with the stock solution while maintaining in the test-stock mixture the difference in known absorbance characteristics between the first dye and the second dye;

d. measuring the absorbance values of the first dye and the second dye in the sample solution at a first wavelength and a second wavelength; and

e. determining the volume of the test-stock mixture aliquot by using the measured absorbance values of the sample solution and the absorbance per pathlength of either or both of the first dye and second dye.

9. The method of claim 8 wherein the liquid holder is a multi-well plate.

10. The method of claim 8 wherein step (e) is performed by using computer-executable software stored on a computer-readable medium, the computer-executable software being capable of calculating volume of the test-stock mixture aliquot based upon absorbance values measured by using the method.

11. The method of claim 8 wherein the liquid holder is in the shape of a truncated cone and wherein the step of determining includes the step of calculating the volume of the aliquot by the equation

12. The method of claim 8 wherein the liquid holder is in the shape of a truncated square-based pyramid and wherein the step of determining includes the step of calculating the volume of the aliquot by the equation