Metabolites of furazolidone in urine of chickens.
Colostomized chickens were medicated with single oral doses of the antibacterial furazolidone. An average of 7.5 ± 3.0% of the dose was excreted in the urine within 12 hr. as compounds measured by a procedure in which they react to form 5-nitrofurfural phenylhydrazone. Chromatographic analysis delected four metabolites containing a furan ring. Only one metabolite reacted to form 5-nitrofurfural phenylhydrazone. Elimination of the metabolites with a furan ring was complete in 12 hr. Only traces of furazolidone were detected by the chromatographic procedure.
Forensic issues in the analysis of trace nitrofuran veterinary residues in food of animal origin
Abstract Over the past twelve years hundreds of official analyses for nitrofuran antibiotic residues in farmed shrimp and prawns have led to product recalls, border rejections, and de-listed suppliers. Positive-release testing regimes have been instigated at huge economic cost. There have been repeated occasions when new scientific information or policy clarification has led to enforcement decisions being seen in a new light and current practice continues to evolve. There remain discrepancies between results found pre-harvest and pre-export in some countries, and results from Border Inspection Posts' analyses when consignments arrive at their destination, despite international harmonisation of test methods and quality criteria. Forensic issues around enforcement decisions following laboratory results for non-compliant consignments containing nitrofurans are summarised herein, including those that have been referred for technical appeal to the UK Government Chemist. Current best practice is collated and specific recommendations and suggestions made for the decision-making process in food safety enforcement. We recommend an approach to semicarbazide analysis from core flesh, removal of ice glaze prior to analysis and that measurement uncertainty is subtracted from the mean result to yield a ‘not less than’ figure used for reporting purposes ‘beyond reasonable doubt’. Research is needed to fill knowledge gaps with regard to sample homogeneity and sampling protocols for nitrofurans in food of animal origin. Sampling should be standardised, as has been established for mycotoxin controls and a modern toxicology risk assessment of nitrofurans and their metabolites in food appears to be warranted.
THE IRON-ACETOCARMINE METHOD OF FIXING AND STAINING CHROMOSOMES
A short description of this procedure was given in Vol. 55 of the American Naturalist, pp. 573â€”574. The method has now been used almost daily for five years, and certain improvements have suggested themselves. The solution can be prepared by mixing about equal volumes of glacial acetic acid and water. To this is added powdered carmine in excess. The liquid is then â€ ? just brought to boil, cooled, and decanted. To the red solution there are then added a few drops of a solution of ferric hydrate in 50 per cent. acetic acid, to act as a mordant. The amount of iron varies with different objects. Too much produces a precipitate in a short time. The more