Rapid determination of furazolidone residues in animal foods by time-resolved fluorescence immunochromatography

Although furazolidone (FZD) was completely banned from livestock production in many countries many years ago due to its mutagenicity and carcinogenicity, the abuse of FZD is still common today. Accurate and rapid detection of FZD residues in animal-derived food products is highly important for human health. Here, a time-resolved fluorescence immunochromatography (TRFI) test strip for rapid and quantitative detection of 3-amino-2-oxazolidinone (AOZ) residues in animal foods was developed and validated. Its limit of detection and limit of quantification were 0.05 and 0.14 μg/kg, respectively. The typical recovery rates were 95-105 % in chicken breast samples spiked with the AOZ standard substance at concentrations of 0.05-2 μg/kg, with a coefficient of variation value ≤8.5 %. The cross-reaction rates of the TRFI-AOZ test strips with 3-amino-5-morpholinomethyl-2-oxazolidone, semicarbazide, and 1-amino-imidazolidin-2,4-dione were less than 1 %. The newly developed TRFI test strip has high sensitivity, high specificity, cost effectiveness and user-friendly control, and is suitable for the rapid and large-scale screening of AOZ residues in animal foods.

In-situ growth of MOF-derived Co3S4@MoS2 heterostructured electrocatalyst for the detection of furazolidone

The over-exploitation of antibiotics in food and farming industries ruined the environmental and human health. Consequently, electrochemical sensors offer significant advantages in monitoring these compounds with high accuracy. Herein, MOF-derived hollow Co3S4@MoS2 (CS@MS) heterostructure has been prepared hydrothermally and applied to fabricate an electrochemical sensor to monitor nitrofuran class antibiotic drug. Various spectroscopic methodologies have been employed to elucidate the structural and morphological information. Our prepared electrocatalyst has better electrocatalytic performance than bare and other modified glassy carbon electrodes (GCE). Our CS@MS/GCE sensor exhibited a highly sensitive detection by offering a low limit of detection, good sensitivity, repeatability, reproducibility, and stability results. In addition, our sensor has shown a good selectivity towards the target analyte among other potential interferons. The practical reliability of the sensor was measured by analyzing various real-time environmental and biological samples and obtaining good recovery values. From the results, our fabricated CS@MS could be an active electrocatalyst material for an efficient electrochemical sensing application.

Lateral flow immunoassay for furazolidone point-of-care testing: Cater to the call of saving time, labor, and cost by coomassie brilliant blue labeling

Furazolidone (FZD) and its metabolite called 3-amino-2-oxazolidinone (AOZ) would induce carcinogenic and mutagenic effects to human. In this work, to develop a novel, stable, and simple point of care testing (POCT) with a potential to social applied for FZD detection, we utilized the aspect of protein staining of coomassie brilliant blue (CBB) to exploit a new CBB-LFIA strategy free of NPs. Only one mixing step is needed during the probe manufacturing process, which requires just 2 h and is a great time saving strategy compared with other methods (requiring 4-33 h for probe preparation). Besides, the cost of CBB-LFIA is 300 times lesser than other LFIA with respect to obtaining the label. The developed CBB-LFIA was successfully applied to detect AOZ with a detection limit of 2 ng mL^-1, without any influence from other potential interfering compounds. The proposed CBB-LFIA exhibited prominent practical application, and possesses considerable utilization potential in the related field.

Competitive Lateral Flow Immunoassay Relying on Au-SiO2 Janus Nanoparticles with an Asymmetric Structure and Function for Furazolidone Residue Monitoring

Gold nanoparticles (AuNPs) are the most commonly used signal materials in lateral flow immunoassay (LFIA). However, the assay sensitivity of traditional AuNP-based LFIA is usually limited by the incomplete competition between free target analytes and immobilized antigens for the binding of AuNP-labeled antibodies. To unfreeze this limitation, here, asymmetric Au-SiO₂ Janus NPs (about 66 nm) were designed and synthesized. Au-SiO₂ Janus NPs can assemble into snowman-like anisotropic structures and combine two different physicochemical properties at their opposite sides, where the AuNP side mainly possesses the antibody conjugating and signal providing functions and the SiO₂ side primarily offers the stable function. In virtue of the unique asymmetric nanostructure, only the AuNP side can interact with target analytes by specific antigen-antibody interactions, which could significantly improve the efficiency of competition. Selecting furazolidone as a model analyte, the immunoassay biosensor showed a limit of detection as low as 0.08 ng/mL, 10-fold decreased than that of the AuNPs-LFIA. Moreover, the Au-SiO₂ Janus NP lateral flow immunoassay was well applied in chicken, pork, honey, and beef food samples with visual detection limits of 0.8 ng/g, 0.16 ng/g, 0.4 ng/mL, and 0.16 ng/g, respectively. The Au-SiO₂ Janus NPs possess the advantages of both materials, which will broaden their applications as a potential alternative in the rapid and sensitive detection of antibiotic residues.

Ultrasonic preparation of near-infrared emission cluster-based YbIII and NdIII coordination materials: Ratiometric temperature sensing, selective antibiotics detection and "turn-on" discrimination of l-arginine

Currently near-infrared (NIR) luminescence of lanthanide ions has received great attention because of their unique emissions in the near-infrared region (800-1700 nm). These NIR luminescent materials behave excellent applications in many fields such as sensors and probes in optical amplification, laser systems, biological systems and organic light-emitting diodes. In this work, two new near-infrared (NIR) emission three-dimensional (3D) Yb^III and Nd^III cluster-based coordination materials, namely {[Yb₂(L)₂(DMF)(H₂O)₄]·(DMF)₂ (H₂O)}_n (NIR-MOF 1) and [Nd(L)(DMF)₂]_n (NIR-MOF 2) (H₃L = terphenyl-3,4″,5-tricarboxylic acid) have been synthesized through the facile sono-chemical preparation methods. Both the near-infrared materials 1 and 2 have been characterized by single crystal X-ray diffraction, powder X-ray diffraction (PXRD) and scanning electron microscopy (SEM). Further the mixed-lanthanide near-infrared emission material Nd_0.35Yb_0.65L (NIR-MOF 3) can also be prepared under the sono-chemical conditions. NIR-MOF 3 can be successfully applied as the ratiometric NIR-MOF-based thermometer, which should origin from the emission intensity ratio between Yb³⁺ (976 nm) and Nd³⁺ (1056 nm) in the temperature range of 308-348 K. Besides these, the micro-morphologies of NIR-MOF 1 can be deliberately tuned through different sono-chemical reaction factors (reaction time, reaction temperature and sono-chemical powers). These tuned nano-sized materials NIR-MOF 1 (100 W, 80 min) can be utilized as the fluorescent sensing material to distinguish furazolidone and sulfasalazine from other antibiotics. At the same time, NIR-MOF 2 can be applied as the first example of MOFs-based sensors for discriminating l-arginine from other amino acids through the "turn-on" mode in the near-infrared emission region.

Novel UV-spectrophotometric method for quantitative estimation of furazolidone using mixed hydrotropic agent

A novel, eco friendly, accurate, sensitive, economic and safe spectrophotometric method was developed by application of mixed hydrotropy using 2 M sodium acetate, 8 M urea, 2 M niacinamide and 2 M sodium benzoate solution (25:25:25:25% V/V) as hydrotropic agent, for the solubalizing of poorly water-soluble Furazolidone (FZ) (solubility:- 3.64e-01 mg/mL in water). There were more than 32 times enhancements in the solubility of FZ were found in mixed hydrotropic solution as compared to solubilities in distilled water. FZ shows maximum absorbance at 360 nm where sodium acetate, urea, niacinamide, sodium benzoate and other tablets excipients did not show any absorbance above 300 nm, and thus no interference in the estimation was seen. FZ was obeyed Beers law in the concentration range of 10 to 50 μg/ml (r(2)=0.9992) in mixed hydrotropic solvent with mean recovery ranging from 97.32% to 98.9%. Proposed method is new, simple, economic, safe, rapid, accurate and reproducible and was validated according to ICH guidelines and values of accuracy, precision and other statistical analysis were found to be in good accordance with the prescribed values.

Development of an indirect competitive ELISA for the detection of furazolidone marker residue in animal edible tissues

Due to its carcinogenicity and mutagenicity, furazolidone has been prohibited completely from being used in food animal production in the world since 1995. To monitor the illegal abuse of furazolidone, a polyclonal antibody-based indirect competitive enzyme-linked immunosorbent assay (ic-ELISA) was developed for the determination of tissue-bound furazolidone metabolite 3-amino-2-oxazolidone (AOZ). The highly specific antibody was targeted for PAOZ, the benzaldehyde derivative of AOZ. The 50% inhibition values (IC 50) of 0.91 microg/L for AOZ was achieved with the most sensitive antibody Ab-B1 by altering ELISA conditions. In the ELISA, sample extraction and cleanup were performed by an is MAX cartridge following combined hydrolysis of the tissue-bound AOZ and derivatization of the homogenized tissues with benzaldehyde. The limits of detection (LOD) calculated from the analysis of 20 known negative tissue samples (swine liver, swine muscle, chicken liver, chicken muscle,and fish muscle) were 0.3-0.4 microg/kg (mean+3 SD). Recoveries of AOZ fortified at the levels of 0.4, 1, and 5 microg/kg ranged from 55.8 to 96.6% in the tissues. The coefficients of variation were less than 20% over the range of AOZ concentrations studied. The linear detection range was between 0.1 and 25.6 microg/L. Validation of the ELISA method with swine muscle and liver from furazolidone-treated pigs was carried out using HPLC, resulting in a similar correlation in swine muscle (r=0.99) and in swine liver (r=0.98). The results suggest that this ELISA is a specific, accurate, and sensitive method of detecting AOZ residues in animal edible tissues.

Determinations of residual furazolidone and its metabolite, 3-amino-2-oxazolidinone (AOZ), in fish feeds by HPLC-UV and LC-MS/MS, respectively

The antibacterial drug furazolidone belonging to the group of nitrofuran antibacterial agents has been widely used as an antibacterial and antiprotozoal feed additive for poultry, cattle, and farmed fish in China. During application a large proportion of the administered drug may reach the environment directly or via feces. Although the use of furazolidone is prohibited in numerous countries, there are indications of its illegal use. It is known that furazolidone can be rapidly metabolized to 3-amino-2-oxazolidinone (AOZ) in the body of the target organism. In this study, a total of 21 fish feed samples, including 17 commercial fish feeds from local markets in China (representing 15 different formulations) and 4 fish feeds obtained from Germany and Turkey, respectively, are analyzed to determine whether the drug is still illegally used or commercially available feeds are contaminated by this drug. High-performance liquid chromatography (HPLC) and liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) methods have been implemented to determine furazolidone and its metabolite AOZ in fish feeds containing animal protein, respectively. An efficient and convenient cleanup method for the determination of furazolidone in fish feeds is developed, and a simple cleanup method for the determination of AOZ is used. Method recoveries for samples used were determined as 87.7-98.3% for furazolidone at two spike levels of 2.0 and 5.0 ng g-1 and as 95.6-102.8% for AOZ at spike levels of 0.4 and 0.8 ng g-1. Limits of detections were 0.4 ng g-1 for furazolidone and 0.05 ng g-1 for AOZ. The established methods are therefore suitable for the determination of furazolidone and its metabolite AOZ in fish feeds at trace contamination levels. Using the established methods, all fish feed samples have been proved to be furazolidone negative; however, AOZ is tested in 16 of 17 fish feeds obtained from local markets in the Hubei province of China, with a positive rate as high as 94.1%.

Detection, accumulation and distribution of nitrofuran residues in egg yolk, albumen and shell

Nitrofuran antibiotics have been banned for use in food-producing animals in many countries, including the European Union, owing to the threat they pose to human health. Research continues into the accumulation of these drugs in animal tissues and into the appropriate methods for their detection. In this study, an LC-MS/MS method is presented for the detection of the parent compounds, furazolidone, nitrofurantoin, furaltadone and nitrofurazone, in eggs. The parent compounds are first extracted into ethyl acetate, fats are removed by partition between acetonitrile and hexane, and the concentrated sample is analysed by LC-MS/MS. Decision limits (CCalpha) for the parents were < or =1 microg kg-1 for all four compounds. Within-day and between-day CVs are well within the limits stated in Commission Decision 2002/657/EC. The method provides an alternative to the testing of side-chain metabolites in eggs, which is particularly important in the case of nitrofurazone, where semicarbazide contamination of food has been attributed to sources other than nitrofurazone use. This method was used together with a method for the detection of the side-chain metabolite compounds, 3-amino-2-oxazolidinone (AOZ), 3-amino-5-morpholinomethyl-1,3-oxazolidin-2-one (AMOZ), 1-amino-hydantoin (AHD) and semicarbazide (SEM), to study the accumulation and distribution of nitrofurans in eggs. Eggs were collected from four groups of hens that had been treated with one of the nitrofurans at a feed concentration of 300 mg kg-1 for 1 week. Parent compounds and metabolites were found in the yolk, albumen and shell. Albumen/yolk ratios for the parent compounds were 0.7, 0.82, 0.83 and 0.31 for furazolidone, furaltadone, nitrofurantoin and nitrofurazone, respectively. Ratios for the side-chain metabolites were 1.02, 1.06, 0.83 and 0.55 for AOZ, AMOZ, AHD and SEM, respectively. However, 50% of the total SEM residues were found in eggshell. This may be significant if eggshell products reach the consumer.

Determination of nitrofurans in animal feeds by liquid chromatography-UV photodiode array detection and liquid chromatography-ionspray tandem mass spectrometry

Within the EU, the use of nitrofurans is prohibited in food production animals. For this reason detection of these compounds in feedingstuffs, at whatever limit, constitutes an offence under EU legislation. This detection generally involves the use of analytical methods with limits of quantification lowers than 1 mg kg(-1). These procedures are unsuitable for the detection and confirmation of trace amounts of nitrofurans in feedingstuffs due to contamination. It is well known that very low concentrations of these compounds can be the source of residues of nitrofuran metabolites in meat and other edible products obtained from animals consuming the contaminated feed. The present multi-compound method was capable of measuring very low concentrations of nitrofurantoin (NFT), nitrofurazone (NFZ), furazolidone (FZD) and furaltadone (FTD) in animal feed using nifuroxazide (NXZ) as internal standard. Following ethyl acetate extraction at mild alkaline conditions and purification on NH2 column, the nitrofurans are determined using liquid chromatography with photodiode-array detection (LC-DAD). It was observed a CCalpha ranged from 50 to 100 microg kg(-1). The liquid chromatography-tandem mass spectrometric (LC-MS/MS) procedure was used to confirm the identity of the suspected presence of any of the nitrofuran compounds.

Evaluation of a Bacillus stearothermophilus tube test as a screening tool for anticoccidial residues in poultry

A Bacillus stearothermophilus var. calidolactis C953 tube test was evaluated for its ability in detecting the residue of selected anticoccidial drugs in poultry, specially sulfamethazine, furazolidone, and amprolium. Various concentrations of each drug were injected into chicken liver and kidney tissues and these tissues were tested to determine the drug detection limits for each drug. The detection limit was defined as the drug concentration at which 95 % of the test results were interpreted as positive. The limits of detection in liver tissue were 0.35 microgram/ml for furazolidone, 0.70 microgram/ml for sulfamethazine and 7.80 microgram/ml for amprolium. In kidney tissues, they were 0.30 microgram/ml for furazolidone, 0.54 microgram/ml for sulfamethazine, and 7.6 microgram/ml for amprolium. It was concluded that this tube test could be used to screen for the residue of these three drugs in poultry.

Depletion of four nitrofuran antibiotics and their tissue-bound metabolites in porcine tissues and determination using LC-MS/MS and HPLC-UV

Depletion of the nitrofuran antibiotics furazolidone, furaltadone, nitrofurantoin and nitrofurazone and their tissue-bound metabolites AOZ, AMOZ, AHD and SEM from pig muscle, liver and kidney tissues is described. Groups of pigs were given feed medicated with one of the nitrofuran drugs at a therapeutic concentration (400?mg?kg(-1)) for ten days. Animals were slaughtered at intervals and tissue samples collected for analysis for six weeks following withdrawal of medicated feed. These samples were analysed both for parent nitrofurans (using LC-MS/MS and HPLC-UV), and for tissue-bound metabolites (using LC-MS/MS). The parent drugs were detectable only sporadically and only in pigs subjected to no withdrawal period whatsoever. This confirms the instability of the four major nitrofuran antibiotics in edible tissues. In contrast, the metabolites accumulated to high concentrations in tissues (ppm levels) and had depletion half lives of between 5.5 and 15.5 days. The metabolites of all four drugs were still readily detectable in tissues six weeks after cessation of treatment. This emphasizes the benefits of monitoring for the stable metabolites of the nitrofurans.

The occurrence of nitrofuran metabolites in the tissues of chickens exposed to very low dietary concentrations of the nitrofurans

The global problem of food products contaminated by residues of the banned carcinogenic nitrofuran drugs has prompted research into how such residues accumulate in tissues. In the study described here, two aspects have been investigated where the nitrofurans accumulate in tissues from chickens exposed to either a dietary or an environmental source of contamination. Twenty groups of broilers were fed a diet containing one of the nitrofurans: furazolidone, nitrofurazone, nitrofurantoin or furaltadone at concentrations of 30, 100, 300, 1000 and 3000 microg kg(-1). At the lowest concentration of furazolidone contamination (0.01% of the therapeutic dose) tissue bound AOZ metabolite residues were detected in liver (1.1 +/- 0.2 microg kg(-1)) and in muscle (0.33 +/- 0.03 microg kg(-1)). Similar results were obtained for AMOZ (0.6 +/- 0.2 microg kg(-1) in liver), the tissue bound metabolite of furaltadone. There was no appreciable accumulation of nitrofurantoin in chicken muscle. The AHD metabolite was not detected in muscle from birds fed nitrofurantoin at either 30 or 100 microg kg(-1). For nitrofurazone the concentrations of the SEM metabolite were higher in muscle than in liver for all dietary concentrations. The potential for a contaminated environment to cause nitrofuran residues in chickens was investigated. Six chickens were placed in a pen that was previously occupied by birds fed a diet containing 3000 microg kg(-1) of furazolidone. After 24 hours' exposure of the chickens to the litter in the pen, AOZ residues of 0.13 +/- 0.04 and 0.10 +/- 0.03 microg kg(-1) were detected in liver and muscle, respectively. The results of both experiments have implications for the poultry industry in trying to eliminate nitrofurans from their production systems, and for regulatory analysts faced with the detection of low concentrations of the drugs, both in tissues and in feedingstuffs.

[Determination of furazolidone, carbenoxolone sodium and berberine hydrochloride in wei kang tablets by reversed-phase high performance liquid chromatography(RP-HPLC)]

An HPLC method with gradient elution was developed to separate and determine furazolidone, carbenoxolone sodium and berberine hydrochloride in Wei Kang Tablets on Nova-Pak C18 column (150 mm x 3.9 mm i.d., 4 microns), using acetonitrile-phosphate buffer solution (pH 7.0) as mobile phase and 3,5-dinitrobenzoic acid as the internal standard. Detection was performed with UV detector at 254 nm. The calibration curves were linear within the ranges of 141.2 mg/L -1,270.8 mg/L for furazolidone(r = 0.9997), 100.6 mg/L -905.4 mg/L for carbenoxolone sodium(r = 0.9995) and 99.2 mg/L -892.8 mg/L for berberine hydrochloride(r = 0.9991). The recoveries and RSDs were 99.5% and 1.38% for furazolidone, 100.3% and 1.73% for carbenoxolone sodium, 97.3% and 1.97% for berberine hydrochloride respectively. The results show that this method is simple, rapid, specific, accurate and reproducible.

Resolution of ternary mixtures of nitrofurantoin, furaltadone and furazolidone by partial least-square analysis to the spectrophotometric signals after photo-decomposition

An UV spectroscopic method is proposed to analyze mixtures of the nitrofuran derivatives, nitrofurantoin, furaltadone and furazolidone, used in veterinary. The change of absorption spectra due to photo-decomposition is used. A 20% dimethylformamide/water, basic medium of pH 9.4 (ammonium chloride/ammonia) and a time of irradiation of 15 s are selected. Calibration graphs are established, with the percentage of decrease of absorbance as analytical signal, in the range 2-10 microg ml(-1). To analyze mixtures of the three compounds the partial least-squares (PLS) multivariate analysis method is used with the spectra obtained by subtracting the spectra after irradiation to the original spectra. Good results have been obtained in the analysis of synthetic samples and a formulation containing all these compounds.

Use of solid phase extraction for the isolation and clean-up of a derivatised furazolidone metabolite from animal tissues

A method is presented for the determination of protein-bound residues of furazolidone in animal tissue. The use of furazolidone in food-producing animals has been banned in the EU. Illegal use of furazolidone can be monitored most effectively by testing for bound residues containing the 3-amino-2-oxazolidone (AOZ) moiety which, unlike the parent drug, is stable and can be detected for prolonged periods after cessation of treatment. This paper reports the development of an extraction and clean-up procedure for AOZ from liver using solid phase extraction. The method replaces solvent extraction and provides extensive sample clean-up with removal of approximately 99% of the derivatising agent, 2-nitrobenzaldehyde, which may interfere with the determination. It also offers the advantage of being suitable for automation, thereby increasing throughput of samples. The extraction procedure may be used for HPLC and ELISA screening techniques. The method has been validated in fortified and incurred pig liver samples, yielding mean recovery of AOZ in excess of 60%.

Evaluation of the residues of furazolidone and its metabolite, 3-amino-2-oxazolidinone (AOZ), in eggs

The use of furazolidone in food-producing animals is banned within the EU. Detection of the protein-bound side-chain metabolite, 3-amino-2-oxazolidinone (AOZ), in animal tissues is the most effective method of enforcing the ban. The study was undertaken to find out if the same applies to eggs. The concentrations of furazolidone and AOZ in eggs reached a plateau of approximately 360-380 microg kg(-1) by the fourth day of treating birds with 400 mg kg(-1) furazolidone. After a 4-day withdrawal from treatment, intact furazolidone could not be detected. AOZ residues could still be detected up to 21 days following withdrawal from treatment. During treatment, most intact furazolidone residues occur in the albumen. For AOZ, there is a more even distribution of residues between albumen and the yolk. The concentration of furazolidone in egg homogenates stored at -20 degrees C decreases by 44% after 55 days. AOZ residues are stable during this period. From these results, it is clear that AOZ is a more suitable marker residue than the parent compound for monitoring concentrations of the drug in eggs.

High-performance liquid chromatographic determination of carbadox, olaquindox, furazolidone, nitrofurazone, and nitrovin in feed

A high-performance liquid chromatography with gradient programming method was developed to determine the amount of carbadox (CBX), olaquindox (OLQ), furazolidone (FZ), nitrofurazone (NF), and nitrovin (NTV) in feed simultaneously. Complete separation of the drugs was obtained using a C8 silica gel column with gradients of acetonitrile as mobile phase. The mobile phase used an acetonitrile gradient with an initial hold time of 1 min at 0% acetonitrile, followed by an increase to 50% acetonitrile over 10 min. The correlation coefficients (r) for calibration curves of the five feed additives were greater than 0.999. The relative standard deviations (RSDs) of peak areas from four injections for these drugs at three concentrations were less than 3.0%, although the RSD for NTV at 5 ppm was somewhat large (6.7%). The medicated feeds were extracted by pretreating with water, extracted with 95% dimethylformamide overnight at room temperature, and cleaned up on a column of alumina oxide. Recoveries of CBX, OLQ, FZ, NF, and NTV from low level spiked feed were 102.0, 94.6, 97.4, 110.6, and 66.0%, respectively, and from high level spiked feed, they were 114.09, 99.1, 97.3, 109.9, and 62.7%, respectively.

Furazolidone residues in pigs: criteria to distinguish between treatment and contamination

The use of furazolidone in food-producing animals has been banned in the EU. The ban can most effectively be enforced by monitoring for bound residues containing the 3-amino-2-oxazolidinone (AOZ) moiety. Unlike the parent drug, AOZ residues are stable and can be detected for prolonged periods after cessation of treatment. However, AOZ can be passed from pig-to-pig following brief exposure of unmedicated animals to housing that previously contained medicated pigs. We describe criteria by which a distinction may be drawn between pigs treated illegally with the drug and pigs that contain detectable AOZ residues as a result of exposure to contaminated housing. These criteria are that illegally treated pigs will have a concentration ratio of AOZ in bile:kidney of less than 0.3; while unmedicated pigs will have a concentration ratio of AOZ in bile:kidney of greater than 3.0. Using this criteria, 12 pigs, either treated with the drug or exposed to contaminated housing were analysed in a blind study. The pigs were classified as 'Treated' or 'Contaminated' on the basis of the criteria described above. All 12 pigs were assigned to the correct group. This shows that it is possible to differentiate between furazolidone abuse and contamination.

Simultaneous determination of tinidazole, furazolidone and diloxanide furoate in a combined tablet preparation by second-derivative spectrophotometry

A second-derivative spectrophotometric procedure has been developed for the simultaneous determination of tinidazole (TD), furazolidone (FD) and diloxanide furoate (DF) in a commercial preparation. The method consists of the utilization of second-derivative absorption spectra of tablet extract in distilled water and then determination of the analyte concentration in the mixture was carried out using zero-crossing (ZC) and ratio-compensation (RC) techniques. Calibration graphs constructed at their wavelengths of determination were linear in the concentration range of TD (5-20 microg ml(-1)), FD (2.5-10 microg ml(-1)) and DF (7.5-15 microg ml(-1)). The results were found to be accurate and free from interference. The details of the statistical treatment of analytical data are also presented.

Application of the bivariate spectrophotometric method for the determination of metronidazole, furazolidone and di-iodohydroxyquinoline in pharmaceutical formulations

The bivariate calibration algorithm was applied to the spectrophotometric determination of metronidazole, furazolidone and di-iodohydroxyquinoline in pharmaceutical dosage forms. The results obtained were compared with the results of derivative spectrophotometry. The statistical evaluation of method bias was carried out, and it was shown that the proposed procedure may be competitive with commonly used first-derivative spectrophotometry. The advantage of the bivariate calibration is its simplicity, and the fact that there is no need to use the derivatization procedures.

Determination of nitrofurantoin, furazolidone and furaltadone in milk by high-performance liquid chromatography with electrochemical detection

A HPLC method with coulometric detection has been established to carry out the separation of the three nitrofuran derivatives, nitrofurantoin, furazolidone and furaltadone. A Nova-Pak C18 column (150 x 3.9 mm) and a Coulochem II detector from ESA have been used. After obtaining the hydrodynamic curves of the three compounds in the porous graphite electrode a potential of -600 mV was selected as the working potential. The influence of other variables such as mobile phase composition and flow-rate were studied. The mobile phase considered as an optimum was acetonitrile-0.1 M aqueous solution of sodium perchlorate (28:72), with 0.5% glacial acetic acid. The oxygen of the mobile phase was removed with a vacuum system on-line and a nitrogen stream was used to remove the oxygen of the samples. The calibration graphs and the detection limits were established. The method proposed was used, with good results, for the determination of the three compounds in milk.

Active transport of nitrofurantoin across the mammary epithelium in vivo

Nitrofurantoin is a commonly used urinary tract antibiotic that has been found at high concentrations in human milk. In vivo studies in rats were carried out to determine the mechanism by which this drug crosses the mammary epithelium. Lactating rats were gavage-fed with nitrofurantoin, and their milk and plasma levels of the antibiotic were measured at intervals up to 8 hr. The average milk-to-plasma (M/P) ratio, calculated from the areas under the milk and plasma curves, respectively, was 23 compared with a ratio predicted to be about 0.3 on the basis of lipid partitioning and protein binding determinations. M/P ratios for two nitrofurantoin congeners were also calculated. The neutral compound furazolidone had a M/P ratio of about 1, as predicted, whereas the basic compound furaltadone had a M/P ratio of 3.49 compared with a predicted ratio of 1.4. These data suggest that nitrofurantoin and, to a lesser extent, furaltadone are actively transported across the mammary epithelium into milk.

Analysis of protein-bound metabolites of furazolidone and furaltadone in pig liver by high-performance liquid chromatography and liquid chromatography-mass spectrometry

Studies undertaken using radiolabelled furazolidone have demonstrated the covalent binding of residues of the drug to cellular protein in vivo. A portion of these bound residues and those formed by furaltadone, a related nitrofuran drug, possess intact side-chains, 3-amino-2-oxazolidinone (AOZ) and 5-morpholino-methyl-3-amino-2-oxazolidinone (AMOZ), respectively. These side-chains have molecular characteristics in common with the parent compounds and may be released from liver tissue under mild acidic conditions. Derivatization with 2-nitrobenzaldehyde (NBA) serves to isolate the released side-chains and the derivatives NPAOZ and NPAMOZ are chromophoric, thereby permitting UV detection. This paper reports the introduction of an extract clean-up step to the existing procedure which eliminates or decreases interference from NBA in the HPLC-UV determination of NPAOZ. The modified procedure was also applied to the determination of AMOZ. The development of an LC-MS method for the quantitative and confirmatory determination of AOZ and AMOZ extracted and derivatized according to the same procedure as that for HPLC-UV is described. The methods were validated for AOZ and AMOZ in fortified (intra- and inter-assay studies) and incurred (inter-assay studies) pig liver samples. The limit of determination for fortified control liver samples was 5 ng AOZ g-1 and 10 ng AMOZ g-1 by HPLC-UV and 10 ng AOZ or AMOZ g-1 by LC-MS. In addition, a study to determine the ratio of released AOZ to the total bound residues present in incurred liver samples from pigs treated with furazolidone is described.

Determination of furazolidone in porcine tissue using thermospray liquid chromatography-mass spectrometry and a study of the pharmacokinetics and stability of its residues

A method is presented for the detection of the nitrofuran, furazolidone, in porcine tissue. Following methanol-buffer extraction of the tissue, liquid partitioning, and solid-phase clean-up, samples are analysed by using thermospray LC-MS monitoring the positive ion m/z 243 with filament-assisted ionization. The LOD is 1 microgram kg-1. The assay is used to investigate the depletion of furazolidone from tissue and sample stability post mortem. It is necessary to snap-freeze samples by immersion in liquid nitrogen immediately upon collection in order to improve the stability of residues in tissue.

Liquid chromatographic determination of furazolidone in swine serum and avian egg

A rapid, simple, and accurate method for determination of furazolidone (FZ) in swine serum and avian egg using liquid chromatography (LC) with a 358 nm ultraviolet-visible spectrophotometric detector is described. After liquid-liquid extraction of sample with ethyl acetate using Extrelut-3, the extract is evaporated, redissolved in 40% acetonitrile, and injected directly into the chromatograph. The antibiotic can be analyzed within 30 min. Within-day recoveries for swine serum and avian egg spiked with FZ at 1 ppm were 90.0 and 88.1%, respectively, with coefficients of variation of 3.52 and 3.88%, respectively. Between days recoveries for the 1 ppm samples were 87.2 and 87.0%, with coefficients of variation of 3.10 and 4.29%, respectively. Determination of FZ also was performed by LC/mass spectrometry (MS) with an atmospheric-pressure chemical-ionization interface (APCI) system. The LC/MS-APCI system is more applicable for qualitative analysis than quantitative analysis because the drug detection limit (about 0.1 microgram/L) is almost the same as that of the LC-UV detector.

Liquid chromatographic determination of furazolidone in shrimp

A liquid chromatographic (LC) method was developed for the quantitation of furazolidone residues in shrimp muscle. The shrimp homogenate (1.0 g) is extracted with acetonitrile, and the extract is taken to dryness. The residue is dissolved in acetonitrile, and the solution is passed through alumina and C18 cleanup columns. The eluate is taken to dryness and reconstituted in a suitable solvent for reversed-phase (C18) LC with UV detection at 365 nm. Recoveries of furazolidone from shrimp homogenates spiked from 5 to 80 ng/g ranged from 74.3 to 79.7%, and relative standard deviations (RSDs) were 5.0-8.9%. RSDs for incurred furazolidone quantitated at 5.9 and 9.2 ng/g were 6.6 and 7.6%, respectively.

Simultaneous determination of nitrofurazone, nitrofurantoin, and furazolidone in channel catfish (Ictalurus punctatus) muscle tissue by liquid chromatography

A liquid chromatographic (LC) method was developed for the simultaneous determination of nitrofurazone (NFZ), nitrofurantoin (NFT), and furazolidone (FZD) in catfish muscle tissue. The drugs were extracted from the tissue with acetonitrile, and the lipids were removed from the extract with hexane. The acetonitrile extract was evaporated by rotary evaporation, and the resultant drug residues were dissolved with LC mobile phase. The mixture was sonicated, centrifuged, and filtered. The drugs were determined by using LC with a C18 reversed-phase (ODS Hypersil) column, a mobile phase of acetonitrile-1% aqueous acetic acid (25 + 75), and a photodiode array ultraviolet detector at 375 nm. NFZ, NFT, and FZD were each determined in catfish tissue at 5 fortification levels (80, 40, 20, 10, and 5 ng drug/g tissue). Average recoveries of each of the 3 drugs at each level ranged from 70.7 to 101.5%, and relative standard deviations ranged from 2.2 to 18.6%. The limit of detection of each drug was approximately 1 ng drug/g tissue, and the limit of quantitation was 5 ng drug/g tissue. In the second part of the study, the method was used to determine nitrofuran residues incurred in catfish tissue. Live channel catfish were intravascularly doses (10 mg/kg body wt) with NFZ to generate drug-incurred fish muscle tissue. Incurred NFZ levels exceeded 400 ng drug/g tissue at 2 h after dosing but decreased rapidly to approximately 1 ng drug/g tissue by 8 h after dosing, as determined by this method.

Simultaneous determination of nitrofurazone and furazolidone in shrimp (Penaeus vannamei) muscle tissue by liquid chromatography with UV detection

A liquid chromatographic (LC) method was developed for the simultaneous determination of nitrofurazone (NFZ) and furazolidone (FZD) in shrimp muscle tissue. The drugs are extracted from the tissue with acetonitrile, and the lipids and lipophilic pigments are removed from the extract with hexane. The remaining acetonitrile extract is evaporated by rotary evaporation, and the resultant residues are dissolved with LC-grade water, applied to a preconditioned C18 solid-phase extraction column, and eluted with acetonitrile. The acetonitrile eluant is then dried under nitrogen, and the resultant drug residues are dissolved with mobile phase and filtered. The drugs are determined by LC by using a C18 reversed-phase (octyldecylsilyl Hypersil) column, a mobile phase of acetonitrile--1% aqueous acetic acid (25 + 75, v/v), and a photodiode array UV detector at 375 nm. NFZ and FZD were determined in shrimp tissue at each of 5 spiking levels (64, 32, 16, 8, and 4 ng drug/g tissue). Absolute recoveries ranged from 70.6 to 78.4%, and relative standard deviations ranged from 4.0 to 13.6%. The limit of detection of pure standard of each drug was approximately the equivalent of 1 ng drug/g tissue, and the limit of determination in a sample was 4 ng drug/g tissue.

Liquid chromatography-electrochemical detection of furazolidone and metabolite in extracts of incurred tissues

One-day-old chicks were raised to maturity on a diet fortified with 0.0055% furazolidone. Analyses of tissue extracts by a liquid chromatographic-electrochemical detection screening procedure for nitro-containing drugs disclosed, in addition to the parent drug, an unidentified metabolite in the liver and breast tissue of the mature birds sacrificed while on the fortified feed. No evidence of residues of the drug or metabolite was found in birds removed from the medicated feed 48 h prior to sacrifice. In view of the rapid in vivo and postmortem metabolism of the parent drug in liver tissue, the metabolite can serve as an alternative means of detecting furazolidone residues in chicken tissues.

Detection of furazolidone in human biological fluids by high performance liquid chromatography

Furazolidone has normally been administered as a non-absorbable antimicrobial agent for use in gastrointestinal infections. However, in India and Mexico it has been used successfully for the treatment of typhoid fever. We measured concentrations of furazolidone by high performance liquid chromatography (HPLC) in several biological fluids, after a single oral dose (5 mg/kg). Six healthy adult volunteers and seven children with typhoid fever and ten children with purulent meningitis were studied. In adults the peak serum concentration was less than or equal to 0.84 mg/l and less than or equal to 4.78% of the ingested dose was excreted in the urine. In the children concentrations were similar to those found in volunteers. The cerebrospinal fluid/serum ratio ranged from 1.02 to 5.95 in the meningitis patients. HPLC is a rapid and sensitive method for the quantitation of furazolidone in biological fluids. The minimum detectable concentration was 0.05 mg/l, with a precision of 6% from peak area and an average recovery of 98%.

Liquid chromatographic method for determination of furazolidone in premixes and complete feeds: collaborative study

A liquid chromatographic (LC) method for determining furazolidone in finished feeds and premixes was collaboratively studied. Finished feed sample is extracted with acetone-water (93 + 7) on a Goldfisch apparatus, extracting solvent is removed, and the residual material is dissolved in warm DMF. A solution of tetraethylammonium bromide is added, the fat layer is removed, and the sample is clarified by filtration and injected onto a reverse phase LC system with detection at 365 nm. Premixes, extracted by shaking with DMF and diluted so that the final furazolidone concentration is about 55 micrograms/mL, are chromatographed and detected the same as finished feed samples, using a mobile phase of acetonitrile-2% acetic acid (20 + 80). Ten commercial feed samples were preweighed and supplied to 14 collaborators. The 5 matched pairs were chosen to represent the following allowed levels: 0.0055, 0.022, 0.033, 2.2, and 22%. Two familiarization samples at the 0.0055 and 11% levels were also supplied. Instructions called for a single analysis of each sample. Two results were eliminated by the Dixon test. The coefficients of variation, following treatment by the ranking test, ranged from 2.0 at the 22% level to 6.5 at the 0.0055% level. Calculated F-values are not significant (P greater than 0.01) except for the 0.0055% level samples extracted overnight. This method has been adopted official first action.

Liquid chromatographic monitoring of the depletion of carbadox and its metabolite desoxycarbadox in swine tissues

A liquid chromatographic method was used to monitor a depletion study of carbadox (and its most important metabolite, desoxycarbadox) in young pigs fed carbadox-treated rations for 1 week. Carbadox was found in blood (20 ppb), blood serum (26 ppb), and muscle tissue 24 h after withdrawal from treated ration; residues were reduced to a trace (less than 2 ppb) in 48 h, and eliminated by 72 h. Desoxycarbadox, although not detected in blood, was found in muscle (17 ppb) 24 h after withdrawal; it was reduced to 9 ppb at 48 h and to a trace by 72 h. Although no carbadox was detected in liver 24 h after withdrawal, appreciable desoxycarbadox (125 ppb) was found in liver 24 h after withdrawal; it was reduced to 17 ppb at 48 h and to a trace by 72 h. Whereas only a trace of carbadox was found in kidney 24 h after withdrawal, 186 ppb desoxycarbadox was found in kidney at 24 h, 34 ppb at 48 h, and a trace at 72 h. No metabolite of carbadox other than desoxycarbadox was found in extracts of swine tissues during this medicated feed trial, and no metabolite was found in blood extracts by using the established methodology. The effect of tissue storage (aging) at -20 degrees C on levels of the drug and its metabolite was a modest alteration of residue levels. The inadvertent use of feed adulterated with furazolidone and initially medicated with chlortetracycline, sulfamethazine, and penicillin G, did not affect the uptake of carbadox in this depletion study or interfere with the analytical methodology.

Determination of furazolidone residues in eggs by HPLC followed by confirmation with a diode-array UV/Vis detector

A sensitive HPLC method for the determination of furazolidone residues in eggs (10-1,000 micrograms/kg) is described. Recovery is about 86%. With the aid of a UV/Vis Diode-Array detector confirmation up to the 15-ppb level was possible. In order to test this method with "real" samples, three laying hens received 30 mg each of furazolidone in feed (single dose). The eggs were collected for five days. After five days traces of furazolidone (5 micrograms/kg) could still be detected.

Furazolidone residues in chicken and swine tissues after feeding trials

Broiler chickens and swine fed furazolidone in their diet were sacrificed, and samples of liver, kidney, skin/fat and muscle were harvested and analyzed for furazolidone residue. Chickens fed 200 g of furazolidone/ton of feed were withdrawn from treatment 21, 14, 7, 5, 3, or 0 days before slaughter. Birds withdrawn from medication more than 5 days prior to slaughter had no residues in any of the tissues sampled. One of the 12 birds in each of the 5 day and 3 day withdrawal groups had detectable residues in the skin/fat. Seven of the 12 birds in the 0 day withdrawal group had residues of less than 2 ppb in skin/fat samples. Chickens fed 400 g furazolidone/ton of feed were withdrawn from treatment 0 days before slaughter. Residues of 0.7 to 3.5 ppb were found in the skin of these birds; residues were not found in other tissues. Swine were fed 300 g furazolidone/ton of feed for 2 weeks or 150 g/ton for 5 weeks. They were withdrawn from treatment 10, 7, 5, 3, or 0 days before slaughter. Tissue samples taken from these swine did not contain detectable furazolidone residues.

High pressure liquid chromatographic determination of nitrofurazone and furazolidone in chicken and pork tissues

A high pressure liquid chromatographic (HPLC) procedure is presented for the determination of nitrofurazone and furazolidone in chicken and pork tissues in the 2-40 ppb range. Muscle, liver, and kidney are homogenized with cold methanol and water (50 + 50). Following methanol evaporation, the nitrofurans are partitioned into ethyl acetate and cleaned up on an alumina column. After elution with 20% methanol in ethyl acetate and evaporation to dryness, residues are determined by HPLC, using a reverse phase analytical column. Overall average recoveries for nitrofurazone and furazolidone were 65.7 and 73.5%, respectively. Average relative standard deviations of 11.9% (nitrofurazone) and 9.5% (furazolidone) at the 2 ppb level were achieved.

Some pharmacological and toxicological properties of furazolidone

The pharmacological and toxicological properties of furazolidone have been briefly reviewed. Among the most important pharmacological actions of furazolidone is the inhibition of mono- and diamine oxidase activities, which seem to depend, at least in some species, on the presence of the gut flora. The drug also seems to interfere with the utilization of thiamin, which is probably instrumental in the production of anorexia and loss of body weight of the treated animals. Furazolidone is known to induce a condition of cardiomyopathy in turkeys, which could be used as a model to study alpha 1-antitrypsin deficiency in man. The drug is most toxic to ruminants. The toxic signs observed were of nervous nature. Experiments are in progress in this laboratory to try to explain the mechanism(s) by which this toxicity is brought about. It is uncertain whether the use of furazolidone at the recommended therapeutic dose would result in drug residues in tissues of treated animals. This is a matter of public health importance as the drug has been shown to possess a carcinogenic activity. It is important that a simple and reliable method of identification and estimation of furazolidone residues be devised. More work is needed to elucidate the mode of action and biochemical effects caused by the drug in both the host and the infective organisms.

Furazolidone in turkey tissues following a 14-day feeding trial

Feed supplemented with furazolidone was fed to turkeys on a research farm near Modesto, CA. The birds fed furazolidone-medicated feed were housed in isolated pens in a manner to prevent any cross contamination from an adjoining treatment. Furazolidone-medicated feed was supplied to the ration for 14 days prior to withdrawal with two exceptions; the controls were not fed medicated feed, and a 400 g/ton treatment was fed for 24 hr prior to processing. Treatments, representing different withdrawal periods, ranged from 0 to 21 days. Two 400 g/ton treatments with 0-day withdrawal periods were included in the study. One of these treatments involved a 14-day medicated feeding period while the other was for 24 hr. All other treatments were fed medicated feed at the rate of 200 g/ton. Tissue samples from the processed birds included skin, fat, liver, kidney, as well as breast and thigh muscle. No detectable residues were found in any of the liver, kidney, fat, or muscle tissues at any of the withdrawal periods including the 0-day withdrawal groups. Skin tissues contained detectable furazolidone residues only in the 0-day withdrawal treatments, and even these levels were below the 2 ppb level.

Ultra trace determination of furazolidone in turkey tissues by liquid partitioning and high performance liquid chromatography

A simple and sensitive procedure is presented for the determination of furazolidone in turkey tissues, using liquid partitioning followed by high performance liquid chromatography (HPLC). Fat, liver, kidney, skin, and muscle tissues are ground with methylene chloride in a Polytron homogenizer, followed by solvent removal, partitioning in hexane-0.01M acetic acid, and back-partitioning the 0.01M acetic acid with methylene chloride. The determination by HPLC used a reverse phase Ultrasphere-ODS 5 micrometer column. The method is sensitive to 0.5 ppb, with a standard deviation of 6.39% at the 2 ppb fortification level. Recovery from fortified tissues averaged 84% from samples fortified with 0.5-10 ppb furazolidone. An alternative cleanup procedure using a Sep-Pak C18 cartridge is also presented.

High performance liquid chromatographic determination of furazolidone in feed and feed premixes

Furazolidone is separated from finished feeds by acetone-water extraction on a Goldfisch apparatus. Extracting solvent is removed, and the residue is dissolved in dimethylformamide-5% tetraethylammonium bromide (1 +1), clarified, and chromatographed on a reverse phase C1 column. The mobile phase is CH3CN-2% acetic acid (20 + 80) with detection at 365 nm. The method was tested for linearity, recovery, and ruggedness, and compared with the AOAC colorimetric assay by using field samples containing 0.0055-0.055% furazolidone. Precision data suggest a cumulative relative standard deviation of 1.43% within days and 1.78% between days. The ruggedness test predicts a between-laboratory relative standard deviation of 3.67%. Recovery was 97.5 +/- 2.0% and linearity was excellent (r2 = 0.9994) up to 0.06% furazolidone. Premixes are extracted by shaking with dimethylformamide. An aliquot of the extract is diluted (1 + 1) with 5% tetraethylammonium bromide, clarified, and chromatographed.

Simultaneous spectrophotometric determination of nifuroxime and furazolidone in pharmaceutical preparations

Two spectrophotometric methods have been developed for the simultaneous determination of nifuroxime and furazolidone in their pharmaceutical preparations. No preliminary separation step is required in either method. The first, a modified Vierordt method, gives accurate and reproducible results for both drugs. Mean percent recoveries for nifuroxime and furazolidone were 99.50 +/- 1.59 and 100.20 +/- 1.16 (P = 0.05), respectively. This method also gives accurate and reproducible results for the determination of nifuroxime and furazolidone in their pharmaceutical preparations: Tricofuran vaginal suppositories and powder. The second method, which involves the use of the first-derivative curves, gives unreliable results; the reasons for these are discussed.

Sample preparation of carbadox, furazolidone, nitrofurazone, and ethopabate in medicated feeds for high pressure liquid chromatography

Medicated feeds (pelleted or mash) containing guarantees of carbadox, furazolidone, nitrofurazone, and ethopabate are pretreated with water, extracted with 95% dimethylformamide overnight at room temperature, cleaned up on a column of alumina, and injected into a high pressure liquid chromatograph for quantitative measurement. Carbadox, nitrofurazone, and furazolidone can be separated; chromatograms show excellent baseline resolution, and results are in good agreement with colorimetric methods. The same extraction and cleanup can be used to improve colorimetric methods for furazolidone and nitrofurazone.