Composition and device for detecting leukocytes in urine

A composition comprising:

• (a) a compound of the formula
• 18
• or a salt or solvated salt thereof, wherein
• A is an N-blocked amino acid residue or N-blocked peptide chain;
• and
• R1 and R2 are each independently hydrogen, unsubstituted or substituted aryl, unsubstituted or substituted heteroaryl, unsubstituted or substituted alkyl, unsubstituted or substituted alkenyl, unsubstituted or substituted alkoxy, amino, unsubstituted or substituted acyl, halo, nitro, cyano, —SO3H, or hydroxy, wherein R1 and R2 are not both hydrogen;
• and
• (b) a diazonium salt.

A diagnostic device for detecting leukocytes and proteinase in urine, comprising:

• an inert carrier having deposited thereon a compound of the formula:
• 21
• or a salt or solvated salt thereof, wherein
• A is an N-blocked amino acid residue or N-blocked peptide chain;
• and
• R1 and R2 are each independently hydrogen, unsubstituted or substituted aryl, unsubstituted or substituted heteroaryl, unsubstituted or substituted alkyl, unsubstituted or substituted alkenyl, unsubstituted or substituted alkoxy, amino, unsubstituted or substituted acyl, halo, nitro, cyano, —SO3H, or hydroxy, wherein R1 and R2 are not both hydrogen.

A method for detecting the presence of leukocytes in urine, comprising contacting a urine sample with a diazonium salt and a compound of the formula:

• 24
• or a salt or solvated salt thereof, wherein
• A is an N-blocked amino acid residue or N-blocked peptide chain;
• and
• R1 and R2 are each independently hydrogen, unsubstituted or substituted aryl, unsubstituted or substituted heteroaryl, unsubstituted or substituted alkyl, unsubstituted or substituted alkenyl, unsubstituted or substituted alkoxy, amino, unsubstituted or substituted acyl, halo, nitro, cyano, —SO3H, or hydroxy, wherein R1 and R2 are not both hydrogen.