Reagent composition, dry element and method for determination of total bilirubin

Claim 2

A reagent composition comprising a diazonium salt or reagents capable of producing a diazonium salt when contacted with water, and 3,3-dimethylglutaric acid or a salt thereof present in an amount effective to buffer said composition at a pH of about 3.5 or less when contacted with a 2 μL sample of pooled human serum.

Claim 3

The reagent composition of claim 1 wherein said diazonium salt is represented by the structure: ##STR2## wherein X - is a stabilizing anion; Y is --CO-- or --SO 2 --; R 1 and R 2 are independently selected from hydrogen, alkyl, aralkyl, aryl carboxyalkyl and hydroxyalkyl; and R 3 and R 4 are independently selected from groups such that the sum of the Hammett sigma values for R 3 and R 4 does not exceed +0.4 or R 3 and R 4 , taken together, represent the carbon atoms necessary to complete a fused carbocyclic arylene moiety.

Claim 4

The reagent composition of claim 2 wherein X - is an anion of a Lewis acid coordinatively saturated by a hydrogen halide, Y is --SO 2 --, R 1 is hydrogen and R 2 is carboxymethyl.

Claim 5

The reagent composition of claim 3 wherein said diazonium salt is 4-(N-carboxymethylsulfamyl)benzenediazonium hexafluorophosphate.

Claim 6

An aqueous reagent solution comprising a diazonium salt buffered at a pH of 3.5 or less with at least about 0.01 M of 3,3-dimethylglutaric acid or a salt thereof.

Claim 7

An aqueous reagent solution comprising a diazonium salt buffered at a pH of 3.5 or less with at least about 0.01 M of 3,3-dimethylglutaric acid or a salt thereof.

Claim 8

The reagent solution of claim 5 wherein said acid or salt thereof is present at from about 0.05 M to about 0.5 M.

Claim 9

A dry analytical element for the determination of total bilirubin in an aqueous liquid, said element comprising a carrier matrix and a reagent composition comprising a diazonium salt or reagents capable of producing a diazonium salt when contacted with water, and 3,3-dimethylglutaric acid or a salt thereof present in an amount effective to buffer said composition at a pH of 3.5 or less when contacted with a 2 μL sample of pooled human serum.

Claim 10

A dry analytical element for the determination of total bilirubin in an aqueous liquid, said element comprising a carrier matrix and a reagent composition comprising a diazonium salt or reagents capable of producing a diazonium salt when contacted with water, and 3,3-dimethylglutaric acid or a salt thereof present in an amount effective to buffer said composition at a pH of 3.5 or less when contacted with a 2 μL sample of pooled human serum.

Claim 11

The element of claim 7 wherein said diazonium salt is represented by the structure: ##STR3## wherein X - is a stabilizing anion, Y is --CO-- or --SO 2 --; R 1 and R 2 are independently selected from hydrogen, alkyl, aralkyl, aryl, carboxyalkyl and hydroxyalkyl; and R 3 and R 4 are independently selected from groups such that the sum of the Hammett sigma values for R 3 and R 4 does not exceed +0.4 or R 3 and R 4 taken together, represent the carbon atoms necessary to complete a fused carbocyclic arylene moiety.

Claim 12

A dry analytical element for the determination of total bilirubin in an aqueous liquid, said element comprising: a support having thereon a porous spreading zone; said spreading zone containing a reagent composition comprising a diazonium salt or reagents capable of producing a diazonium salt when contacted with water, said salt represented by the structure: ##STR4## wherein X - is a stabilizing anion; Y is --CO-- or --SO 2 --; R 1 and R 2 are independently selected from hydrogen, alkyl, aralkyl, aryl, carboxyalkyl and hydroxyalkyl; and R 3 and R 4 are independently selected from groups such that the sum of the Hammett sigma values for R 3 and R 4 does not exceed +0.4 or R 3 and R 4 , taken together, represent the carbon atoms necessary to complete a fused carbocyclic arylene moiety, and

Claim 13

A dry analytical element for the determination of total bilirubin in an aqueous liquid, said element comprising: a support having thereon a porous spreading zone; said spreading zone containing a reagent composition comprising a diazonium salt or reagents capable of producing a diazonium salt when contacted with water, said salt represented by the structure: ##STR4## wherein X - is a stabilizing anion; Y is --CO-- or --SO 2 --; R 1 and R 2 are independently selected from hydrogen, alkyl, aralkyl, aryl, carboxyalkyl and hydroxyalkyl; and R 3 and R 4 are independently selected from groups such that the sum of the Hammett sigma values for R 3 and R 4 does not exceed +0.4 or R 3 and R 4 , taken together, represent the carbon atoms necessary to complete a fused carbocyclic arylene moiety, and

Claim 14

3-dimethylglutaric acid or a salt thereof present in an amount effective to buffer said composition at a pH of about 3.5 or less when contacted with a 2 μL sample of pooled human serum.

Claim 15

3-dimethylglutaric acid or a salt thereof present in an amount effective to buffer said composition at a pH of about 3.5 or less when contacted with a 2 μL sample of pooled human serum.

Claim 16

The element of claim 9 wherein X - is an anion of a Lewis acid coordinatively saturated by a hydrogen halide, Y is --SO 2 --, R 1 is hydrogen and R 2 is carboxymethyl.

Claim 17

The element of claim 10 wherein said diazonium salt is 4-(N-carboxymethylsulfamyl)benzenediazonium hexafluorophosphate.

Claim 18

A dry analytical element for the determination of total bilirubin in an aqueous liquid, said element comprising: a support having thereon, in order and in fluid contact, a hydrophilic layer containing 3,3-dimethylglutaric acid or a salt thereof present in an amount effective to buffer said hydrophilic layer at a pH of about 3.5 or less when contacted with a 2 μL sample of pooled human serum, and an isotropically porous spreading/reagent layer containing a diazonium salt or reagents capable of producing a diazonium salt when contacted with water, said salt represented by the structure: ##STR5## wherein X - is a stabilizing anion; Y is --CO-- or --SO 2 --; R 1 and R 2 are independently selected from hydrogen, alkyl, aralkyl, aryl, carboxyalkyl and hydroxyalkyl; and R 3 and R 4 are independently selected from groups such that the sum of the Hammett sigma values for R 3 and R 4 does not exceed +0.4 or R 3 and R 4 , taken together, represent the carbon atoms necessary to complete a fused carbocyclic arylene moiety.

Claim 19

A dry analytical element for the determination of total bilirubin in an aqueous liquid, said element comprising: a support having thereon, in order and in fluid contact, a hydrophilic layer containing 3,3-dimethylglutaric acid or a salt thereof present in an amount effective to buffer said hydrophilic layer at a pH of about 3.5 or less when contacted with a 2 μL sample of pooled human serum, and an isotropically porous spreading/reagent layer containing a diazonium salt or reagents capable of producing a diazonium salt when contacted with water, said salt represented by the structure: ##STR5## wherein X - is a stabilizing anion; Y is --CO-- or --SO 2 --; R 1 and R 2 are independently selected from hydrogen, alkyl, aralkyl, aryl, carboxyalkyl and hydroxyalkyl; and R 3 and R 4 are independently selected from groups such that the sum of the Hammett sigma values for R 3 and R 4 does not exceed +0.4 or R 3 and R 4 , taken together, represent the carbon atoms necessary to complete a fused carbocyclic arylene moiety.

Claim 20

The element of claim 12 wherein said hydrophilic layer comprises a mordant.

Claim 21

The element of claim 12 wherein said diazonium salt is selected from the group consisting of: 4-(N-carboxymethylsulfamyl)benzenediazonium hexafluorophosphate; 4-[N,N-bis(carboxymethyl)sulfamyl]benzenediazonium hexafluorophosphate; 4-[N,N-bis(2-hydroxyethyl)sulfamyl]benzenediazonium hexafluorophosphate; 4-(N-carboxymethylcarbamyl)benzenediazonium tetrafluoroborate; 4-(N-carboxypropylcarbamyl)benzenediazonium naphthylenedisulfonate; 4-(N-carboxymethylsulfamyl)benzenediazonium tetrafluoroborate; 4-(N-dodecylsulfamyl)benzenediazonium tetrafluoroborate; 3,5-dichloro-4-(N-carboxymethylsulfamyl)benzenediazonium hexafluorophosphate; 4-(N-carboxymethylsulfamyl)-1-diazonium naphthylene hexafluorophosphate; 7-[N-tris(hydroxymethyl)methylcarbamyl]-4-diazoniumindene hexafluorophosphate; and 4-[N,N-bis(carboxymethyl)sulfamyl]-1-diazonium-6-methoxy naphthylene chlorozincate.

Claim 22

The element of claim 12 wherein said acid or salt thereof is present in a coverage of from about 1 to about 7.5 g/m 2 .

Claim 23

The element of claim 12 wherein said acid or salt thereof is present in an amount effective to buffer said hydrophilic layer at a pH of from about 1 to about 3.5 when contacted with a 2 μL sample of pooled human serum.

Claim 26

The method of claim 17 wherein said diazonium salt is represented by the structure: ##STR6## wherein X - is a stabilizing anion; Y is --CO-- or --SO 2 --; R 1 and R 2 are independently selected from hydrogen, alkyl, aralkyl, aryl, carboxyalkyl and hydroxyalkyl; and R 3 and R 4 are independently selected from groups such that the sum of the Hammett sigma values for R 3 and R 4 does not exceed +0.4 or R 3 and R 4 , taken together, represent the carbon atoms necessary to complete a fused carbocyclic arylene moiety.

Claim 27

The method of claim 17 wherein said sample is contacted with a dry analytical element comprising a support having thereon, in order and in fluid contact, a hydrophilic layer containing said acid and a spreading/reagent layer containing said diazonium salt.

Claim 28

The method of claim 19 wherein said hydrophilic layer comprises a mordant.