Patent ID: 7632928

Claim:
A nitrofuran metabolite compound of the formula wherein P is selected from the group consisting of a bifunctional cross-linker alone, a bifunctional cross-linker conjugated further to a protein carrier, a peptide conjugated to a protein carrier, a protein, a nucleic acid, a polysaccharide, or a combination thereof; wherein R 1 is either H or part of a heterocyclic ring structure said ring structure including R 2 ; wherein R 2 is selected from the group consisting of NH, O when part of the heterocyclic ring structure or NH 2 when not part of the heterocyclic ring structure; and wherein Z is selected from the group consisting essentially of —CN, —OH, —O—CO2H, halides, carboxylate, —OR where R is an alkyl or acyl group of a low carbon chain of 11 carbons or fewer and —NHR where R is an alkyl or acyl group of a low carbon chain of 11 carbons or fewer.