Carcinoembryonic antigen determination

Claim 1

A method of determining the concentration of carcinoembryonic antigen in a sample of serum or plasma from a human which comprises: (a) adding sufficient buffer to a sample of serum or plasma to produce a pH of from about 6.0 to about 6.5; (b) adding hydrophilic silica having a BET surface area of from 100 to 400 m 2 /g and an average primary particle size of from 7-16 nanometer to said sample and incubating said sample to neutralize materials in said sample which would interfere with determination of CEA; (c) separating the silica from the sample; (d) adding an excess of an antibody to CEA to said sample and incubating for a predetermined time; (e) adding to said sample an amount of carcinoembryonic antigen labeled with a labeling substance capable of being quantitatively determined at least sufficient to react with the amount of antibody added in step (d) and incubating for a predetermined time; (f) adding to said sample an insolubilizing agent thus forming a solid phase containing antibody-bound CEA and a liquid phase containing unbound CEA; (g) separating said solid and liquid phases; (h) determining the amount of said labeling substance present in either said solid or said liquid phase; and (i) determining the amount of carcinoembryonic antigen present in said sample by comparison against a standard.

Claim 2

A method of determining the concentration of carcinoembryonic antigen in a sample of serum or plasma from a human which comprises: (a) adding sufficient buffer to a sample of serum or plasma to produce a pH of from about 6.0 to about 6.5; (b) adding hydrophilic silica having a BET surface area of from 100 to 400 m 2 /g and an average primary particle size of from 7-16 nanometer to said sample and incubating said sample to neutralize materials in said sample which would interfere with determination of CEA; (c) separating the silica from the sample; (d) adding an excess of an antibody to CEA to said sample and incubating for a predetermined time; (e) adding to said sample an amount of carcinoembryonic antigen labeled with a labeling substance capable of being quantitatively determined at least sufficient to react with the amount of antibody added in step (d) and incubating for a predetermined time; (f) adding to said sample an insolubilizing agent thus forming a solid phase containing antibody-bound CEA and a liquid phase containing unbound CEA; (g) separating said solid and liquid phases; (h) determining the amount of said labeling substance present in either said solid or said liquid phase; and (i) determining the amount of carcinoembryonic antigen present in said sample by comparison against a standard.