Determination of beta-19-nortestosterone and its metabolite alpha-19-nortestosterone in biological samples at the sub parts per billion level by high-performance liquid chromatography with on-line immunoaffinity sample pretreatment.
ABSTRACT An immunoaffinity precolumn (immuno precolumn) packed with Sepharose-immobilized polyclonal antibodies against the anabolic hormone 17 beta-19-nortestosterone (beta-19-NT) was used for the selective on-line pretreatment of raw extracts of urine, bile and tissue samples by high-performance liquid chromatography. Using UV detection (247 nm), beta-19-NT and its metabolite 17 alpha-19-nortestosterone (alpha-19-NT) can be determined in biological samples with a detection limit of 0.05 microgram/kg. Owing to the high clean-up efficiency of the immuno precolumn and the large sample volumes used, confirmation by gas chromatography-mass spectrometry is possible at this level. In urine samples from a calf treated with 19-nortestosterone 17 beta-laurate, the maximum concentrations of beta-19-NT (1.3 micrograms/l) and alpha-19-NT (3.1 micrograms/l) were found seven days after intramuscular administration. In a bile sample from this calf only alpha-19-NT (55 microgram/l) was detected. In meat samples from three treated calves, the concentration of beta-19-NT varied from 0.1 to 1.6 micrograms/kg and no alpha-19-NT could be detected. In liver samples from these calves, the concentrations of beta-19-NT and alpha-19-NT were less than 0.05-0.1 and 0.5-0.9 micrograms/kg, respectively. In the corresponding kidney samples, the concentrations of beta-19-NT and alpha-19-NT were 0.4-0.5 and 0.5-1.6 micrograms/kg, respectively. The application of the same immuno precolumn to the determination of 17 beta- and 17 alpha-trenbolone, two structurally related steroids, is also demonstrated.
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ABSTRACT: The thesis was based on a project financed by the DFG with the title Determination of Polar Pesticides by Immunoextraction-Tandem Mass Spectrometry (IAC-LC-MS/MS) Using Sulfonylurea Herbicides as Model Compounds. Its aim was the development of class-specific antibodies and their application as selective receptors for the enrichment of sulfonylureas from environmental and food samples. First of all three different immunogens were synthesized and employed for polyclonal and monoclonal antibody production. The gained polyclonal anti-sulfonylurea-antibody possessing the broadest specificity was used to establish a class-specific ELISA for rapid and cost-effective sample monitoring. For immunosorbent preparation corresponding antibodies were immobilized in sol-gel glasses. Advantages and limitations of immunosorbents in off- and on-line-applications were shown for water and food matrices spiked with sulfonylureas. Liquid chromatographic techniques combined with UV/DAD- and MS/MS-detection were used for the sulfonylurea determination.
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ABSTRACT: A simple procedure for the enzymic digestion of edible tissues is described and compared with other procedures. The samples are digested overnight in an enzyme suspension containing subtilisin A at 60 degrees C and pH 9. The resulting digest contains only a few small tissue fragments. This method is suitable for routine analysis, since the manipulation of the samples is very limited.Zeitschrift für Le0bensmittel-Untersuchung und -Forschung 03/1991; 192(2):105-7.
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ABSTRACT: A method is described for the determination of residues of the antibiotic chloramphenicol in biological samples. The method is based on gas chromatography/negative ion chemical ionization mass spectrometry and uses (37Cl2)chloramphenicol as internal standard. Selective ion monitoring of four analyte-specific ions enables the determination of chloramphenicol levels in urine of 3 micrograms l-1 with a coefficient of variation of 8%. The limit of detection of the method is 0.1 p.p.b. for urine, muscle and egg.Biological Mass Spectrometry 01/1992; 20(12):763-70. DOI:10.1002/bms.1200201204