Method for determining the volume of particles suspended in liquids

• US 6,359,683 B1
• Filed: 04/27/2000
• Issued: 03/19/2002
• Est. Priority Date: 04/27/2000
• Status: Expired due to Fees

• Current Assignee: Becton, Dickinson & Co
• Original Assignee: Becton, Dickinson & Co
• Inventors: Berndt, Klaus W.
• Primary Examiner(s): Font, Frank G.
• Assistant Examiner(s): Punnoose, Roy M.
• Application Number:
  US09/560,078
• Time in Patent Office: 691 Days
• Field of Search: 356/39, 356/335, 356/627
• US Class Current: 356/39
• CPC Class Codes: G01N 15/06 Investigating concentration of particle suspensions by weighing G01N5/00; investigating sedimentation of particle suspensions G01N15/04; investigating individual particles G01N15/10
• CPC Class Codes: G01N 2015/012 Red blood cells
• CPC Class Codes: G01N 2015/055 for hematocrite determination
• CPC Class Codes: G01N 2015/1493 Particle size
• CPC Class Codes: G01N 2021/6439 with indicators, stains, dyes, tags, labels, marks

Abstract

The present invention relates to the field of quantitative microspectroscopy, and in particular to a method for determining the volume of particles that are suspended in liquids.

Claims

1. A method for determining the volume of particles that are suspended in a liquid sample comprising:

a) depositing said liquid sample that contains suspended particles into an optical cuvette having an entrance window and an output window at a known distance (X₀) from each other;

b) adding and evenly distributing a light-absorbing dye into the liquid sample that does not leak into the suspended particles;

c) sending light of such a wavelength through the cuvette that said light is highly absorbed by the added dye, but only weakly absorbed by the suspended particles;

d) measuring the optical transmission through the cuvette in an area that contains no particles (I₁/I₀);

e) measuring the optical transmission through the cuvette in an area that contains particles (I₃/I₀′

); and

f) calculating the volume of the suspended particles based on these transmission values and the known distance of the cuvette windows.

2. The method of claim 1 wherein said light-absorbing dye is a fluorescent dye.

3. The method of claim 1 wherein said light-absorbing dye is TO-PRO-3 or TO-PRO-5.

4. The method of claim 1 wherein said cuvette is a thin cuvette which has a distance between the entrance window and the output window of about 1 micron to about 3000 microns.

5. The method of claim 1 wherein said cuvette is a thick cuvette having a distance between the entrance window and the output window of about 1 micron to about 50 cm.

6. The method of claim 1 wherein said volume is calculated by the equation:

$V={\mathrm{Ax}}_0<br><br>\left[1-\frac{\lg <br><br>\left(I_3/I_0^{\mathrm{\prime <br><br>}}\right)}{\lg <br><br>\left(I_1/I_0\right)}\right]$

wherein X₀, I₃/I₀′

, and I₁/I₀ are as defined in claim 1;

V is the volume of the particle;

A is the area of the particle as determined by an imaging photodetector; and

lg is logarithm.

7. The method of claim 1 wherein said liquid sample is blood.

8. The method of claim 7 wherein said cuvette is a thin cuvette which has a distance between the entrance window and the output window of about 1 micron to about 50 microns.

9. The method of claim 7 wherein said cuvette is a thick cuvette having a distance between the entrance window and the output window of about 1 micron to about 50 microns.

10. The method of claim 7 wherein the suspended particles are red blood cells.

11. The method of claim 7 wherein the suspended particles are white blood cells.

12. The method of claim 7 wherein the suspended particles are platelets.

13. A method for determining the volume of particles that are suspended in a liquid sample comprising:

a) depositing said liquid sample that contains suspended particles into an optical cuvette having an entrance window and an output window;

b) adding and evenly distributing a light-absorbing dye into the liquid sample that does not leak into the suspended particles;

c) sending light of such a wavelength through the cuvette that said light is highly absorbed by the added dye, but only weakly absorbed by the suspended particles;

d) measuring the light intensity (I₁) reemerging from the cuvette in an area that contains no particles and where the entrance window and the output window have a first distance from each other;

e) measuring the light intensity (I₃) reemerging from the cuvette in an area that contains a particle and where the entrance window and the output window have said first distance from each other;

f) measuring the light intensity (I₄) reemerging from the cuvette in an area that contains no particles and where the entrance window and the output window have a second distance from each other;

g) measuring the light intensity (I₅) reemerging from the cuvette in an area that contains no particles and where the entrance window and the output window have a distance from each other that is different from said second distance by a known amount (Δ

x);

h) calculating the volume of the suspended particles based on the intensity values (I₁, I₃, I₄, and I₅), said known amount of the difference in the distances (Δ

x) and the area (A) that is occupied by the particle as determined by an imaging photodetector.

14. The method of claim 13 wherein said light-absorbing dye is a fluorescent dye.

15. The method of claim 13 wherein said light-absorbing dye is TO-PRO-3 or TO-PRO-5.

16. The method of claim 13 wherein said cuvette is a thin cuvette which has a distance between the entrance window and the output window of about 1 micron to about 3000 microns.

17. The method of claim 13 wherein said cuvette is a thick cuvette having a distance between the entrance window and the output window of about 1 micron to about 50 cm.

18. The method of claim 13 wherein said volume is calculated by the equation:

$V=A<br><br>\text{\hspace{1em}<br><br>}<br><br>\frac{\lg <br><br>\left(I_1/I_3\right)}{\lg <br><br>\left(I_4/I_5\right)}<br><br>\text{\hspace{1em}<br><br>}<br><br>{\mathrm{\Delta <br><br>}}_x$

wherein I₁, I₃, I₄, I₅, A and Δ

x are as defined in claim 13;

V is the volume of the particle; and

lg is logarithm.

19. The method of claim 13 wherein said liquid sample is blood.

20. The method of claim 19 wherein said cuvette is a thin cuvette which has a distance between the entrance window and the output window of about 1 micron to about 50 microns.

21. The method of claim 19 wherein said cuvette is a thick cuvette having a distance between the entrance window and the output window of about 1 micron to about 50 microns.

22. The method of claim 19 wherein the suspended particles are red blood cells.

23. The method of claim 19 wherein the suspended particles are white blood cells.

24. The method of claim 19 wherein the suspended particles are platelets.