Nitrofurans, detection

As an aside, one might mention hair as a generally very stable matrix for most drugs and metabolites. These authors detected quantitatively sulfonamide and trimethoprim in horse tail hair 3 years after oral dosing in a horse, at a distance of 45-55 cm from the follicle. For the nitrofurans a MRPL of 1 p-g/kg has been set in the EU. Bound Residues and Nitrofuran Detection (FoodBRAND) comprises a rapid multi-residue screening test and also includes definitive multi-residue reference methods for protein-bound remnants of the nitrofurans. ... 

Draisci, R., Giannetti, L., Lucentini, L., Palleschi, L., Brambilla, G., Serpe, L. and Gallo P. (1997). Determination of nitrofuran residues in avian eggs by liquid chromatography - UV photodiode array detection and confirmation by liquid... 

In addition, specific testing was performed for chloramphenicol in muscle, nitrofurans in muscle and serum, dimefridazole in muscle of pigs and poultry, and sulfonamides in liver. In Australia, chloramphenicol is not registered for use in food animals and nitrofurans are only available as a topical preparation for use in companion animals. No residues of either of these compounds were detected. No residues of dimefridazole were detected in pig and poultry samples. Sulfonamide residues were monitored in cattle and pigs. No residues were detected in 613 cattle samples. In 594 pig liver samples analyzed, 9 residues of sulfamethazine (sulfamethazine) were detected, 4 of which were above the MRL. 

In Poland, samples of muscle, kidneys, and liver from cattle, swine, horses, and poultry are taken four times per year by veterinary inspectors at slaughterhouses to be analyzed for drug residues. Between 1992 and 1996, 5733 samples of cattle, swine, horse, and chickens muscle were analyzed to determine residues of sulfonamides, nitrofurans, and nitroimidazoles 2613 samples of cattle and swine liver to determine -agonists and 1661 samples of cattle and swine kidney to determine violative levels of tranquilizers and -blockers. No residues of the mentioned groups of drugs above MRL were detected in the examined samples (42). However, nonviolative residues of sulfamethazine, sulfadimethoxine, sulfathiazole, furazolidone, nitrofurazone, nitrofurantoin, metronidazole, dimetridazole, azaperone, chlorpromazine, propiopromazine, carazolol, clenbuterol, and salbutamol could be detected in the corresponding target samples. 

Following extraction and cleanup, nitrofurans are separated by thin-layer or liquid chromatography and measured by spectrophotometric, fluorometric, electrochemical, or mass spectrometric detectors (Table 29.5). Thin-layer chromatography has been carried out on commercially available silica gel plates. Nitrofurans were separated using various solvent mixtures as mobile phases and subsequently detected after spraying with pyridine, using spectrophotometric (29) or fluorometric (158, 159) detectors. 

In liquid chromatographic analysis of nitrofuran antibacterials, the most popular detector is the ultraviolet visible (UV-vis) spectrophotometer. Nitrofurans exhibit strong absorption at wavelengths around 365 nm and are, therefore, ideal for direct determination (Table 29.5). Detection wavelengths of 275 nm (56, 57) and 400 nm (175) have also been suggested. Electrochemical detection is also frequently applied in liquid chromatographic methods for the determination of various nitrofuran antibacterials in edible animal products (172, 173, 179). 

Ipso attack has been detected at both a-positions in the reaction of methyl and adamantyl radicals with methyl 5-nitrofuran-2-carboxylate and 5-nitrofuran-2-carbaldehyde. A typical example is shown in Scheme 43. Ipso attack at the carbon bearing the nitro group leads to substitution via the [Pg.617]

Cooper KM, Kennedy DG, Nitrofuran antibiotic metabolites detected at parts per million concentrations in retina of pigs—a new matrix for enhanced monitoring of nitrofuran abuse. Analyst 2005 130 466-468. 

Conneely A, Nugent A, O Keeffe M, Mulder PPJ, van Rhijn JA, Kovacsics L, Fodor A, McCracken RJ, Kenned DG, Isolation of bound residues of nitrofuran drugs from tissue by solid-phase extraction with determination by liquid chromatography with UV and tandem mass spectrometric detection, Ana/. Chim. Acta 2003 483 91-98. 

In 2002 residues of nitrofuran drugs were frequently detected in poultry and shellfish imported into the EU. Action was taken, and the MRPLs for nitrofuran metabolites in poultry meat and aquaculture products were set at 1 pg/kg in 2003." Nitrofuran metabolites are still found primarily in aquaculture products originating from Southeast Asia, with semicarbazide (SEM, the metabolite/marker of nitrofurazone) having the highest incidence. ... 

Methods for detecting residues of nitrofurans should not aim for the parent drugs because these are rapidly metabolized and do not persist in edible tissues. Nitrofurans form protein-bound metabolites that may persist in tissues for considerable periods after treatment. 

A common procedure for the analysis of nitrofuran metabolites involves hydrolysis of the protein-bound metabolites under acidic conditions followed by deriva-tization with 2-nitrobenzaldehyde (Eig. 7.5). After neutralization of the digest, solvent extraction is carried out with ethyl acetate. Residues are detected by LC-UV or LC-MS/MS In some cases an additional liquid-liquid extraction or solid-phase extraction step is applied to remove excessive matrix compounds. A broad overview of applied methods was published by Vass et al. in 2008. ... 

Prior to acidic hydrolysis, the samples are extracted several times with water, methanol, and/or ethyl acetate to remove unbound residues. After removal of excessive organic solvent, samples are hydrolyzed and treated according to standard procedures, resulting in the detection of bound nitrofuran metabolites only. 

Verdon E, Couedor P, Sanders P, Multi-residue monitoring for the simultaneous determination of five nitrofurans (furazolidone, furaltadone, nitrofurazone, nitrofurantoine, nifursol) in poultry muscle tissue through the detection of their five major metabolites (AOZ, AMOZ, SEM, AHD, DNSAH) by liquid chromatography coupled to electrospray tandem mass spectrometry—in-house validation in line with Commission Decision 657/2002/EC, Anal. Chim. Acta 2007 586(l-2) 336-347. 

A comparison of mutagenic activity using normal and nitroreductase-deficient bacteria provides a method for detection and identification of nitroaromatic mutagens. But this idea is complicated by the existence of several bacterial nitroreductases with differing specificities (11). Three different nitroreductase-deficient derivatives of the normal tester strain TA98 were obtained from Dr H. S. Rosenkranz at Case Western University who has isolated and characterized these strains. Strain TA98NR was selected for its resistance to the nitrocompound niridazole and subsequently found to be resistant to the mutagenicity of niridazole, and also to that of the nitrofurans, nitronaphthalenes, and nitrofluorene (3). It is also resistant to 1-nitropyrene and a number of other nitro-PAH... 

Nitrofurans can be separated in NP systems on silica gel and can be detected as colored spots after spraying the plate with pyridine and illuminating with UV light at 366 nm. ... 

UV detection and diode-array detection (DAD) have been widely used, coupled to HPLC, for the analysis of the parent compounds of nitrofurans. The detection wavelengths of nitrofiirans have been set at 368 nm," 365 nm, " 360 nm," 270 nm, or at 254 nm. " An HPLC method, with electrochemical detection, has also been described for the monitoring of furazolidone and furaltadone hydrochloride in chickoi tissues and eggs. " ... 

Particularly, in a residue analysis, identification of detected analytes is required to confirm a result. For nitrofurans analysis, there are a few confirmatory methods reported, including the use of the photodiode-array system and MS detection. The use of a photodiode array detector coupled to HPLC (HPLC-DAD) offers advantages that the target peak can be identified by its retention time and absorption spectrum. In this case, the continuous spectral data generated during the analysis are collected to check for interfering substances by comparing the spectra of samples with those of the standards. However, the specificity and the limit of detection are not sufficient to determine or identify... 

Degroodt, J.M. Wyhowski de Bukanski, B. De Groof, J. Beemaert, H. Srebmik, S. Chloramphenicol and nitrofuran residue analysis hy HPLC and photodiode array detection in meat and fish. J. Liq. Chromatogr. 1992, 75, 2355-2371. 

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