Residue depletion of nitrofuran drugs and their tissue-bound metabolites in channel catfish (Ictalurus punctatus) after oral dosing.

The depletion of the nitrofuran drugs furazolidone, nitrofurazone, furaltadone, and nitrofurantoin and their tissue-bound metabolites [3-amino-2-oxazolidinone (AOZ), semicarbazide (SC), 3-amino-5-morpholinomethyl-2-oxazolidinone (AMOZ), and 1-aminohydantoin (AH), respectively] were examined in the muscle of channel catfish following oral dosing (1 mg/kg body weight). Parent drugs were measurable in muscle within 2 h. Peak levels were found at 4 h for furazolidone (30.

Multiclass determination and confirmation of antibiotic residues in honey using LC-MS/MS.

A multiclass method has been developed for the determination and confirmation in honey of tetracyclines (chlortetracycline, doxycycline, oxytetracycline, and tetracycline), fluoroquinolones (ciprofloxacin, danofloxacin, difloxacin, enrofloxacin, and sarafloxacin), macrolides (tylosin), lincosamides (lincomycin), aminoglycosides (streptomycin), sulfonamides (sulfathiazole), phenicols (chloramphenicol), and fumagillin residues using liquid chromatography tandem mass spectrometry (LC-MS/MS). Erythromycin (a macrolide) and monensin (an ionophore) can be detected and confirmed but not quantitated. Honey samples (approximately 2 g) are dissolved in 10 mL of water and centrifuged.

Determination of nitrofuran residues in milk of dairy cows using liquid chromatography-tandem mass spectrometry.

An analytical method has been developed for the determination of total bound and extractable residues of the nitrofuran drugs furazolidone, nitrofurazone, furaltadone, and nitrofurantoin in milk of dairy cows. The method involves overnight acid hydrolysis and simultaneous derivatization of the released side chains with 2-nitrobenzaldehyde. During hydrolysis, the bound metabolites are hydrolyzed to the side chains.

Determination and confirmation of nitrofuran residues in honey using LC-MS/MS.

A method was developed for the determination and confirmation of furazolidone, nitrofurazone, furaltadone, and nitrofurantoin as their side-chain residues in honey using liquid chromatography-tandem mass spectrometry (LC-MS/MS). An initial solid-phase extraction cleanup of the honey samples was followed by overnight hydrolysis and derivatization of the nitrofuran side-chain residues with 2-nitrobenzaldehyde. After pH adjustment and liquid-liquid extraction, the extracts were assayed by LC-MS/MS using electrospray ionization in the positive ion mode.

Determination of 17alpha-methyltestosterone in muscle tissues of tilapia, rainbow trout, and salmon using liquid chromatography-tandem mass spectrometry.

An analytical method was developed to quantitate and confirm the presence of 17alpha-methyltestosterone in the muscles of tilapia, rainbow trout, and salmon. The method employed two liquid-liquid partitioning steps and two solid-phase extraction columns for sample cleanup. The final extracts were analyzed on an isocratic reverse-phase liquid chromatography-tandem mass spectrometry system with atmospheric-pressure chemical ionization in the positive ion mode.

Liquid chromatography-tandem mass spectrometry for the determination of protein-bound residues in shrimp dosed with nitrofurans.

An analytical method was developed for the determination of bound residues of the nitrofuran drugs furazolidone, nitrofurazone, furaltadone, and nitrofurantoin with a sensitivity of 1 ppb in shrimp. In this procedure, shrimp tissue is prewashed with solvents followed by overnight acid hydrolysis, during which the side chains of the bound residues are released and simultaneously derivatized with 2-nitrobenzaldehyde. After liquid-liquid extraction cleanup, the derivatives are detected and quantitated using liquid chromatography-mass spectrometry/mass spectrometry (LC-MS/MS) with an atmospheric pressure chemical ionization interface.