title: Analysis of 19-nortestosterone residue in animal tissues by ion-trap gas chromatography-tandem mass spectrometry.
abstract: A rapid sample treatment procedure for the gas chromatography-tandem mass spectrometry (GC-MS) determination of 19-nortestosterone (19-NT) in animal tissues has been developed. In our optimized procedures, enzymatic hydrolysis with β-glucuronidase from Escherichia coli was performed in an acetate buffer (pH 5.2, 0.2 mol/L). Next, the homogenate was mixed with methanol and heated at 60 °C for 15 min, then placed in an ice-bath at -18 °C for 2 h. After liquid-liquid extraction with n-hexane, the analytes were subjected to a normal-phase solid phase extraction (SPE) C₁₈ cartridge for clean-up. The dried organic extracts were derivatized with heptafluorobutyric anhydride (HFBA), and then the products were injected into GC-MS. Using electron impact mass spectrometry (EI-MS) with positive chemical ionization (PCI), four diagnostic ions (m/z 666, 453, 318, and 306) were determined. A standard calibration curve over the concentration range of 1-20 ng/g was reached, with Y=467084X-68354 (R²=0.9997) for 19-NT, and the detection limit was 0.3 ng. When applied to spiked samples collected from bovine and ovine, the recoveries ranged from 63% to 101% with relative standard deviation (RSD) between 2.7% and 8.9%. The procedure is a highly efficient, sensitive, and more economical method which offers considerable potential to resolve cases of suspected nandrolone doping in husbandry animals.
authors.affiliation: College of Veterinary Medicine, Northwest A&F University, Yangling 712100, China.
authors.forename: Jin-qing
authors.initials: JQ
authors.lastname: Jiang
authors.forename: Lei
authors.initials: L
authors.lastname: Zhang
authors.forename: Guang-ling
authors.initials: GL
authors.lastname: Li
authors.forename: Hai-tang
authors.initials: HT
authors.lastname: Zhang
authors.forename: Xue-feng
authors.initials: XF
authors.lastname: Yang
authors.forename: Jun-wei
authors.initials: JW
authors.lastname: Liu
authors.forename: Ren-feng
authors.initials: RF
authors.lastname: Li
authors.forename: Zi-liang
authors.initials: ZL
authors.lastname: Wang
authors.forename: Jian-hua
authors.initials: JH
authors.lastname: Wang
mesh_terms: D000818:Animals; D002417:Cattle; D004350:Drug Residues / Q000032:analysis*; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods*; D008460:Meat / Q000032:analysis*; D009277:Nandrolone / Q000032:analysis* / Q000302:isolation & purification; D012756:Sheep; D052616:Solid Phase Extraction; D053719:Tandem Mass Spectrometry / Q000379:methods*
chemical_list: D009277:Nandrolone