Colorimetric assay for urea

Claim 2

A PROCESS FOR DETERMINING THE UREA CONTENT OF FLUIDS COMPRISING: A. MIXING:

Claim 3

ORTHO-PHTHALALDEHYDE,

Claim 4

ORTHO-PHTHALALDEHYDE,

Claim 5

A FLUID SAMPLE,

Claim 6

A FLUID SAMPLE,

Claim 7

The process of claim 1 wherein the orthophthalaldehyde, fluid sample and N-(1-naphthyl) ethylenediamine dihydrochloride are mixed and then heated to approximately 37* C. prior to obtaining a colorimetric reading.

Claim 8

a fluid sample;

Claim 9

a fluid sample;

Claim 10

N-(1-naphthyl) ethylenediamine dihydrochloride; and b. obtaining a colorimetric reading after a period of time for the resulting mixture.

Claim 11

N-(1-naphthyl) ethylenediamine dihydrochloride; and b. obtaining a colorimetric reading after a period of time for the resulting mixture.

Claim 12

The process of claim 1 wherein the orthophthalaldehyde and fluid sample are mixed first and then heated to approximately 37* C. prior to the addition of N-(1-naphthyl) ethylenediamine dihydrochloride.

Claim 13

N-(1-NAPHTHYL) ETHYLENEDIAMINE DIHYDROCHLORIDE, AND B. OBTAINING A COLORIMETRIC READING AFTER A PERIOD OF TIME FOR THE RESULTING MIXTURE.

Claim 14

N-(1-NAPHTHYL) ETHYLENEDIAMINE DIHYDROCHLORIDE, AND B. OBTAINING A COLORIMETRIC READING AFTER A PERIOD OF TIME FOR THE RESULTING MIXTURE.

Claim 15

The process of claim 1 wherein said colorimetric reading is compared to a blank sample, said blank sample comprising a combination of ortho-phthalaldehyde and N-(1-naphthyl) ethylenediamine dihydrochloride.

Claim 16

The process of claim 1 wherein said period of time is less than about 30 minutes.

Claim 17

The process of claim 1 wherein said ortho-phthalaldehyde is present in a solution which is prepared by dissolving from about 100 mg. to about 700 mg. of ortho-phthalaldehyde and about 3/4 ml. of 30 percent polyoxyethylene(23) lauryl ether in about 1000 ml. of 0.1 N sulfuric acid.

Claim 18

The process of claim 1 wherein said N-(1-naphthyl) ethylenediamine dihydrochloride is present in a solution prepared by mixing the following in a ratio as set forth below: a. about 5 g. of boric acid; b. about 600 ml. of water; c. about 220 ml. of concentrated sulfuric acid; d. from about 100 mg. to about 700 mg. of N-(1-naphthyl) ethylenediamine dihydrochloride; e. about 3/4 ml. of 30 percent polyoxyethylene(23) lauryl ether; and f. adding water to make the final volume about 1 liter.

Claim 19

The process of claim 1 wherein said period of time is about 10 minutes.

Claim 20

The process of claim 1 wherein a plurality of colorimetric readings are obtained prior to the endpoint of the reaction whereby the endpoint of the reaction can be predicted.

Claim 21

The process of claim 1 wherein said fluid is blood serum.

Claim 22

A process for determining the urea content of fluids comprising: a. adding equal portions of ortho-phthalaldehyde to a sample container and a blank container; b. adding a fluid sample to said sample container; c. adding equal portions of N-(1-naphthyl) ethylenediamine dihydrochloride to said sample container and said blank container; d. heating said sample container and contents and said blank container and contents to approximately 37* C; e. permitting said reaction to occur at an elevated temperature for a predetermined period of time; f. obtaining a first colorimetric reading for said sample container and a second colorimetric reading for said blank container; and g. whereby the difference between the colorimetric reading for said sample container and said blank container indicates the level of urea in blood serum.

Claim 23

A process for determining the urea content of fluids comprising: a. adding equal portions of ortho-phthalaldehyde to a sample container and a blank container; b. adding a fluid sample to said sample container; c. adding equal portions of N-(1-naphthyl) ethylenediamine dihydrochloride to said sample container and said blank container; d. heating said sample container and contents and said blank container and contents to approximately 37* C; e. permitting said reaction to occur at an elevated temperature for a predetermined period of time; f. obtaining a first colorimetric reading for said sample container and a second colorimetric reading for said blank container; and g. whereby the difference between the colorimetric reading for said sample container and said blank container indicates the level of urea in blood serum.

Claim 24

The process of claim 11 wherein said period of time is less than about 30 minutes.

Claim 25

The process of claim 11 wherein said orthophthalaldehyde is present in a solution which is prepared by dissolving from about 100 mg. to about 700 mg. of orthophthalaldehyde and about 3/4 ml. of 30 percent polyoxyethylene(23) lauryl ether in about 1000 ml. of 0.1 N sulfuric acid.

Claim 26

The process of claim 11 wherein said N-(1-naphthyl) ethylenediamine dihydrochloride is present in a solution prepared by mixing the following in a ratio as set forth below: a. about 5 g. of boric acid; b. about 600 ml. of water; c. about 220 ml. of concentrated sulfuric acid; d. from about 100 mg. to about 700 mg. of N-(1-naphthyl) ethylenediamine dihydrochloride; e. about 3/4 ml. of 30 percent polyoxyethylene(23) lauryl ether; and f. adding water to make the final volume about 1 liter.

Claim 27

The process of claim 11 wherein said predetermined time is about 10 minutes.

Claim 28

The process of claim 11 wherein a plurality of colorimetric readings are obtained prior to the endpoint of the reaction whereby the endpoint of the reaction can be predicted.

Claim 29

The process of claim 11 wherein said fluid is blood serum.