Liquid chromatographic determination of nitrofuran residues in bovine muscle tissues.

A liquid chromatographic (LC) method was developed and statistically validated for simultaneous determination of nitrofurazone, nitrofurantoin, furazolidone, and furaltadone residues in bovine muscle tissues. These antimicrobial residues in samples stabilized at pH 6.0 were extracted with acetonitrile and purified by liquid-liquid partition between dichloromethane-ethyl acetate and hexane saturated with acetonitrile. The acetonitrile-ethyl acetate extract was concentrated, and drug residues were dissolved in LC mobile phase, filtered, and determined by LC. A C18 reversed-phase (ODS Hypersil) column at 35 degrees C, a mobile phase of 0.01M sodium acetate buffer (pH 4.5)-acetonitrile (70 + 30), and a UV/visible diode array detector at 365 nm were used. The retention times and UV spectra of peaks in spiked samples were compared with those of known nitrofurans. Limits of detection (LD) and quantitation (LQ) were 1 and 2 micrograms/kg, respectively. Average recoveries were 76% (range, 60-110%). Relative standard deviations ranged from 6 to 18% at 5 fortification levels from 1.5 to 20 micrograms/kg). (Fortification levels for furaltadone were 3 to 40 micrograms/kg). The method was used to analyze 350 samples per year from 1993 to 1995.

[Disease of the fins of Rhamdia sapo. Isolation of the etiological agents and experimental infection]. / Enfermedad de las aletas de Rhamdia sapo. Aislamiento de los agentes etiológicos e infección experimental.

During intensive culture of South-American catfish, Rhamdia sapo fingerlings an epizootic similar to fin rot was developed. Aeromonas hydrophila and Pseudomonas aeruginosa were isolated and they were treated and controlled with daily short dip, 1 ppm Furanace. The disease was experimentally reproduced and we concluded that it is result of interaction of unfavorable environment conditions such as: low dissolved oxygen, increase of solids in suspension; host condition and the presence of Aeromonas hydrophila and Pseudomonas aeruginosa.

Enfermedad de las aletas de Rhamdia sapo. Aislamiento de los agentes etiológicos e infección experimental. / [Disease of the fins of Rhamdia sapo. Isolation of the etiological agents and experimental infection]

During intensive culture of South-American catfish, Rhamdia sapo fingerlings an epizootic similar to fin rot was developed. Aeromonas hydrophila and Pseudomonas aeruginosa were isolated and they were treated and controlled with daily short dip, 1 ppm Furanace. The disease was experimentally reproduced and we concluded that it is result of interaction of unfavorable environment conditions such as: low dissolved oxygen, increase of solids in suspension; host condition and the presence of Aeromonas hydrophila and Pseudomonas aeruginosa.

Hidrolisis "in vitro" de un ester de ampicilina. I. Valoracion microbiologica. / Hydrolysis in vitro of an ampicillin ester. I. Microbiological assay

Se valora microbiologicamente con una cepa de Sarcina lutea ATCC 9341 la actividad del producto de hidrolisis de un ester de ampicilina (phthalidyl-D- alfa -aminobenzyl - penicillinate hydrochloride) (E.A.).En las experiencias "in vitro" se utilizan los siguientes parametros: pH, tiempos, temperaturas, concentraciones, procesos quimicos y enzimaticos (suero, plasma y sangre total de distintas especies animales) con y sin agitacion. Los mejores datos se obtienen sometiendo la droga a pH 8.0 con 5% de sangre humana, a 37 graus C.+/- 1 grau C, durante 90 minutos, con agitacion

Hidrolisis "in vitro" de un ester de ampicilina. II. Pruebas de sensibilidad de microorganismos de origen humano. / Hydrolysis \"in vitro\" of an ampicillin ester. II. Sensitivity test of microorganisms of human origin

Un hidrolizado de ester de ampicilina se utiliza para investigar la sensibilidad de bacterias Gran negativas y de Staphylococcus aureus, en medio liquido en rango de concentracion de 6 a 14 microgramo/ml.Tambien se realizan pruebas de difusion en agar con discos impregnados con 10 microgramos. El producto de hidrolisis conserva su actividad durante dos semanas a 4 grados C. +/- 1 grado C. Se observa correlacion de datos con ampicilina sodica estander en medio liquido y solido. Los porcentajes de sensibilidad son similares a los obtenidos por otros autores