Nitrofuran antibiotics, employed for the treatment of bacterial diseases in livestock production, were banned from use in the European Union (EU) in 1995 due to concerns about the carcinogenicity of their residues in edible tissue. This review provides an overview of nitrofuran toxicity, metabolism, and also specific aspects of legislation surrounding their prohibition. Special attention is devoted to semicarbazide -a nitrofuran metabolite and food contaminant. Analytical procedures for nitrofuran analysis in various matrices and validation requirements for screening and confirmation methods with respect to EU regulations are also reviewed.Keywords: nitrofurans; tissue bound metabolites; semicarbazide; bioavailability; mutagenicity; legislation; sample preparation; validation; detection methods List of abbreviations AHD = 1-aminohydantoin; AOZ = 3-amino-2-oxazolidinone; AMOZ = 3-amino-5-morpholino-methyl-1,3-oxazolidinone; CC α = decision limit; CC β = detection capability; EC = European Commission; EFSA = European Food Safety Authority; ELISA = enzyme linked immuno-adsorbent assay; ESI = electro-spray ionisation; EU = European Union; FTD = furaltadone; FZD = furazolidone; HPLC = high performance liquid chromatography; IC = inhibition concentration; LC = liquid chromatography; LOD = limit of detection; MS = mass spectrometry; NFT = nitrofurantoin; NFZ = nitrofurazone; NP = nitrophenyl; NPAHD = 3-(2-nitrobenzylidenamino)-2,4-imidazolidinedione); NPAMOZ = 5-(morpholinomethyl)-3-(2-nitrobenzylidenamino)-2-oxazolidinone); NPAOZ = [3-(2-nitrobenzylidenamino)-2-oxazolidinone]; NPSEM = 3[(2-nitrophenyl)methylene]-hydrazinecarboxamide; o-NBA = ortho-nitrobenzaldehyde; RASFF = Rapid Alert System for Food and Feed; SE = solvent extraction; SEM = semicarbazide; SPE = solid phase extraction; UV = ultraviolet

No abstract

Development of antibodies with broad specificity recognition for sulfonamide drugs was found to be surprisingly difficult when conventional immunochemical strategies were applied to hapten design. To improve the cross-reactivity pattern of antibodies for the family of sulfonamide drugs, a novel strategy based on the single-ring (fragment-derived) hapten moieties with different spacer substituent lengths was employed for the preparation of immunogens, coating conjugates, and enzyme competitors. The rabbit antibodies raised against a common (one-ring) p-aminobenzenesulfonamide hapten moiety (attached to a carrier protein through the N-1 position) in combination with a homologous hapten-peroxidase tracer allowed the detection of 15 sulfonamide species at the maximum residue limit level using direct ELISA. The two-ring 6-(4-aminobenzensulfonylamino)hexanoic hapten mimics, previously reported in the literature as a weak generic antigen, generated surprisingly superior immune responses in rabbits. The antibodies raised against this two-ring hapten were capable of detecting at least 19 and 17 sulfonamides in a direct ELISA system at the regulatory level with sensitivities corresponding to 20 and 50% binding inhibition, respectively. A negligible cross-reaction with N4 metabolites makes it possible to measure responses of parent sulfonamides in the presence of their metabolized forms. In skimmed milk, the highest limit of detection (LOD) for sulfacetamide defined as 20% inhibition was 65.2 microg x L(-1) (IC20 value), whereas the additional 18 sulfonamides tested exhibited LODs in the range of 0.2-36.8 microg x L(-1). This sensitivity allows simple multisulfonamide tests to be established for use in the laboratory or on site.

Twelve monoclonal antibodies (MAbs) against the widely used herbicide 2,4-D were produced by hybridomas from two fusions of murine myeloma cells and spleen cells isolated from BALB/c mice immunized with hapten conjugated via the carboxyl group to thyroglobulin. To evaluate the sensitivity and selectivity of MAbs, competitive indirect ELISA was used. MAb E2/G2 exhibited the highest sensitivity toward 2,4-D (IC50 = 0.8 ng/mL) and a favorable selectivity toward 18 structurally related substances. Besides the expected high cross-reactivity with methyl ester 2,4-D (104.8 %), cross-reactivity with MCPA (13.8%) and with 2,4,5-T (9.5%) was found. Cross-reactivity with other structural analogs did not exceed 2.7%. Optimization studies showed that in competitive ELISAs for 2,4-D coating conjugates with hapten densities of 2.3 and 3.3 mol of 2,4-D/mol of BSA were more sensitive than conjugates with hapten densities of 15.9 and 26.5 mol of 2,4-D/mol of BSA. The best dose-response curves presented in this study were almost linear in the concentration range 0.2-10 ng/mL. 2,4-Dichlorophenoxyacetic acid (2,4-D) is a broadly used herbicide for controlling weeds which could potentially contaminate groundwater and the drinking water supply. The allowable limits for pesticide residues in drinking water are becoming lower and lower. In European Community (EC) countries, the maximum admissible concentration is 0.1 ng/mL of any one substance and 0.5 ng/mL for a sum of pesticides, including metabolites (Wittmann and Hock, 1991).Conventional methods of quantitation of polar phenoxyalkanoic acids include liquid-liquid extraction, acidbasic partitioning, chemical derivatization, and purification. This procedure is time-consuming, it involves toxic solvents and reagents, and the results are often inconsistent (Loconto, 1991). Therefore, quick, easy, and economical

No abstract