Perspectives in residue analysis; The use of immobilized antibodies in (multi) residue analysis

Natural sex steroids and their xenobiotic analogs in animal production: growth, carcass quality, pharmacokinetics, metabolism, mode of action, residues, methods, and epidemiology

Natural and xenobiotic compounds having sex-related actions have long been used for growth promotion and various changes in carcass quality in meat animals. The first compounds used were synthetic estrogens; however, later on a whole battery of compounds having androgenic, and progestogenic actions have also been involved. In surveying the effects of these compounds in meat-producing animals, it became clear that these drugs increase the growth rate of the treated animals and bring about changes in the carcass that are generally characterized by lower fat content and more lean mass. Extensive studies undertaken in various countries, including the European Economic Community (EEC), have shown that if used according to good husbandry practices, the meat from treated animals does not have excessive amounts of residues compared with the endogenous amount of steroid production in the animals in question and also in human beings. The banning of these compounds in the European community brought a new phenomenon of illegal or black market cocktails. These mixtures of anabolic steroids are injected into the body of the animals rather than implanted in the ears, which is the normal practice in countries where they have not yet been banned. Several screening and confirmatory methods are now available for monitoring programs. However, these programs need excessive resources in terms of manpower, funds, and proper legislation, which in underdeveloped countries is questionable, particularly in the absence of strong scientific evidence for the exercise.

Automated high-performance liquid chromatographic determination of chloramphenicol in milk and swine muscle tissue using on-line immunoaffinity sample clean-up

An on-line high-performance liquid immunoaffinity chromatographic (HPLIAC) system for the direct determination of chloramphenicol in milk and swine muscle tissue is described. The system consisted of a dual-column system in which an HPLIAC column was directly coupled to an RP-8 high-performance liquid chromatographic column. Skimmed and deproteinated milk or aqueous muscle tissue extract was directly injected into the HPLIAC column. After a washing step with phosphate-buffered saline, chloramphenicol was desorbed by a glycine-NaCl buffer (pH 2.8) and directly concentrated on the RP-8 column. Next, chromatography was carried out using acetonitrile-sodium acetate buffer as the mobile phase. Chloramphenicol was detected at 280 nm. Mean recoveries from spiked raw milk were 70 +/- 2% (1-50 micrograms/kg) and from spiked swine muscle tissue 64 +/- 2% (10-50 micrograms/kg). The calibration curves were linear in the range 1-200 micrograms/kg spiking levels. Limits of determination were 1 microgram/kg for milk and 10 micrograms/kg for muscle tissue.