Composition method for determining the presence of leukocyte cells, esterase or protease in a test sample

A composition for determining the presence or concentration of leukocyte cells, esterase or protease in a test sample, said composition comprising:

• (a) a lactate ester having the structure ##STR25## wherein A is an alcohol blocking group, and wherein B-O- is a residue of a compound B-OH, and provides a detectable response when the lactate ester is hydrolyzed to generate the compound B-OH, wherein the detectable response is chromogenic, fluorescent, a reflectance change, a pH change, chemiluminescent, colorimetric, or spectrophotometric;
• (b) a buffer,
• (c) optionally, an accelerator compound capable of increasing the rate of hydrolysis of the lactate ester;
• and
• (d) optionally, a diazonium salt.

A composition which exhibits a sufficient color transition upon contacting a test sample to demonstrate a presence or concentration of leukocyte cells in the test sample, said composition comprising:

• (a) about 0.5 to about 1.5 mM of a chromogenic lactate ester having the structure ##STR33## wherein A is selected from the group consisting of p-toluenesulfonyl, n-propylsulfonyl, benzoyl, carbomethoxyethane sulfonyl, and thiophene sulfonyl;
• (b) a buffer capable of providing a pH of about 7 to about 10;
• (c) about 0.1% to about 2% (v/v) of an aliphatic alcohol having about 8 to about 15 carbon atoms;
• and
• (d) about 0.1 to about 1 mM of a diazonium salt coupling agent selected from the group consisting of 1-diazo-2-naphthol-4-sulfonate, 1-diazophenyl-3-carbonate, 4-diazo-3-hydroxy-1-naphthylsulfonate, 4-diazo-3-hydroxy-7-nitro-1-naphthylsulfonate, 4-diazo-3-hydroxy-1,7-naphthyldisulfonate, 2-methoxy-4-(N-morpholinyl)benzene diazonium chloride, 4-diazo-3-hydroxy-7-bromo-1-naphthylsulfonate, 4-diazo-3-hydroxy-7-cyano-1-naphthylsulfonate, and 4-diazo-3-hydroxy-7-1-naphthylsulfonate, and mixtures thereof.

A method of assaying a liquid test sample for the presence or concentration of leukocyte cells, esterase or protease comprising:

• (a) contacting the liquid test sample with a reagent composition, said reagent composition comprising:
• (i) a lactate ester having the structure ##STR34## wherein A is an alcohol blocking group, and wherein B-O- is a residue of a compound B-OH and provides a detectable response when the lactate ester is hydrolyzed to generate the compound B-OH, wherein the detectable response is chromogenic, fluorescent, a reflectance change, a pH change, chemiluminescent, colorimetric, or spectrophotometric;
• (ii) a buffer,
• (iii) optionally, an accelerator compound, which increases the rate of hydrolysis of lactate ester, and
• (iv) optionally, diazonium salt coupling agent;
• (b) examining the reagent composition for a detectable response;
• and
• (c) correlating the detectable response to the presence or concentration of leukocyte cells, esterase or protease in the liquid test sample.