Photometric apparatus and method for measuring hemoglobin

Claim 2

A cuvette for making a photometric measurement of a liquid sample comprising: a unitary body of a rigid, solid material having opposing upper and lower faces and opposing first and second side edges; a flow through slot disposed between the upper and lower faces and extending between the first and second side edges; the slot being of a predetermined size such that a liquid sample may be drawn into the slot by capillary action and wherein a liquid cleaning solution will flow through and clean the slot when the body is inserted into and moved through the solution; and the body being optically transparent to allow photometric measurements to be made of a liquid sample in the slot.

Claim 3

The cuvette of claim 1, wherein the slot has a height defined between the opposing upper and lower faces of from about 0.005 to about 0.025 inches.

Claim 4

The cuvette of claim 2, wherein the slot has a length extending between the opposing first and second side edges of from about 0.1 to about 0.3 inches.

Claim 5

The cuvette of claim 3, wherein the slot has a width parallel to the side edges of from about 0.1 to about 0.3 inches.

Claim 6

The cuvette of claim 2, wherein the slot holds a sample of from about 1 to about 20 microliters.

Claim 7

The cuvette of claim 1, wherein the slot is of a predetermined size adapted for making an absorbance measurement with a blood sample.

Claim 8

The cuvette of claim 6, wherein the height of the slot is from about 0.005 to about 0.015 inches.

Claim 9

The cuvette of claim 7, wherein the height of the slot is about 0.01".

Claim 10

The cuvette of claim 1, wherein the body is in the shape of a slide.

Claim 11

The cuvette of claim 1, wherein the body is made of molded plastic.

Claim 12

Apparatus for making a photometric measurement wherein light passes through a liquid sample contained in a cuvette and a photometric detector measures the intensity of light passing through the sample, the improvement comprising: a cuvette comprising a unitary body of a rigid, solid material having opposing upper and lower faces and opposing first and second side edges, a flow through slot disposed between the upper and lower faces and extending between the first and second side edges, the slot being of a predetermined size such that a liquid sample may be drawn into the slot by capillary action and a liquid cleaning solution will flow through and clean the slot when the body is inserted in and moved through the solution, the material being optically transparent to allow a photometric measurement to be made of a liquid sample in the slot; means for measuring the intensity of light passing through the sample in the slot at a first passband wavelength less than the maximum absorbance characteristic of the sample; wherein the predetermined size of the cuvette and the first passband are selected to allow both flow through cleaning of the slot and an absorbance measurement on an undiluted liquid sample.

Claim 13

Apparatus for making a photometric measurement wherein light passes through a liquid sample contained in a cuvette and a photometric detector measures the intensity of light passing through the sample, the improvement comprising: a cuvette comprising a unitary body of a rigid, solid material having opposing upper and lower faces and opposing first and second side edges, a flow through slot disposed between the upper and lower faces and extending between the first and second side edges, the slot being of a predetermined size such that a liquid sample may be drawn into the slot by capillary action and a liquid cleaning solution will flow through and clean the slot when the body is inserted in and moved through the solution, the material being optically transparent to allow a photometric measurement to be made of a liquid sample in the slot; means for measuring the intensity of light passing through the sample in the slot at a first passband wavelength less than the maximum absorbance characteristic of the sample; wherein the predetermined size of the cuvette and the first passband are selected to allow both flow through cleaning of the slot and an absorbance measurement on an undiluted liquid sample.

Claim 14

The apparatus of claim 11 adapted for making an absorbance measurement with a blood sample, wherein the first passband is at about 500 to about 520 nm, and the slot has a height defined between the opposing faces of from about 0.005 to about 0.015 inches.

Claim 15

The apparatus of claim 12, wherein the first passband is centered at about 510 nm and the height of the slot is about 0.01 inches.

Claim 16

The apparatus of claim 11, further comprising: means for measuring the intensity of light passing through the sample in the slot at a second passband wavelength at which substantially no absorbance occurs to enable an accurate absorbance measurement to be made by taking a ratio of the outputs from the first and second measuring means.

Claim 17

The apparatus of claim 14, wherein the first passband is at less than about 50% of the maximum absorbance characteristic and the second passband is at less than about 5% of the maximum absorbance characteristic.

Claim 18

The apparatus of claim 15, adapted for making a photometric absorbance measurement of hemoglobin wherein the first passband is at about 500 to about 520 nm and the second passband is at about 600 to about 900 nm.

Claim 19

The apparatus of claim 16, wherein the first passband is centered at about 510 nm and the second passband is centered at about 650 nm.

Claim 20

The apparatus of claim 17, wherein the slot has a height defined between the opposing faces of from about 0.005 to about 0.015 inches.

Claim 21

The apparatus of claim 14, further comprising: an electronic circuit and a display device, the electronic circuit having measuring means for determining the ratio of the outputs of the two measuring means, means for determining the log of the ratio, means for multiplying the log of the ratio by a constant to produce a result, and means for sending the result to the display device.

Claim 24

The method of claim 20, wherein the first passband is at about 500 to about 520 nm.

Claim 25

The method of claim 21, wherein the first passband is centered at about 510 nm.

Claim 26

The method of claim 21, wherein the second passband is at about 600 to about 900 nm.

Claim 27

The method of claim 21, wherein the intensity measurements are made with an undiluted blood sample of from about 0.005" to about 0.015" in thickness.