| Clenbuterol (CL), one of β-agonists, is often illegally used due to its effect on food animals’growth promotion and lean meat improvement. Because CL is easily accumulated in tissues of foodanimals, it can cause food-borne diseases and bring potential health risks when consuming animaltissues with CL residuals.The study included four parts:(1) An analytical method was developed for the quantification of CL in eye, heart, lung, kidney andspleen of mutton sheep using liquid chromatography-tandem mass spectrometry (LC-MS/MS). After theextraction, and concentration, the extract was loaded on a MCX solid phase extraction column.. CL waseluted from the column by methyl alcohol: ammonia water (95/5, V/V) and was analyzed by theLC-MS/MS. The limits of detection (LOD) were determined to be0.01μg/kg (eye),0.01μg/kg (heart),0.07μg/kg (lung),0.07μg/kg (kidney) and0.03μg/kg (spleen), respectively. The limits ofQuantification (LOQ) for eye, lung, heart, spleen and kidney were0.03μg/kg,0.03μg/kg,0.23μg/kg,0.23μg/kg and0.10μg/kg, respectively. The recovery rates were99.93-102.07%(eye),95.92-108.50%(heart),95.60-109.00%(lung),91.04-109.83%(kidney), and91.46-120.38%(spleen) in aconcentration range of5-20ppb. The relative standard deviation was less than3.95%(eye),8.35%(heart),6.90%(lung),2.22%(kidney) and3.51%(spleen), respectively. The results showed that thedeveloped method reached the detection requirements.(2) The residue distribution and depletion of CL in ovine eye, heart, lung, kidney and spleen aftertreatment with dietary CL were studied. Mutton sheep (n=24;30±5kg) were fed50μg/kg CL for21days．Ovine tissues were collected to determine CL concentrations by LC-MS/MS．The result showedthat the residue concentration of CL was higher in eye. The depletion of CL was slower in eye. CLconcentration in eye was42.42μg/kg-63.48μg/kg on14d after withdrawal. The depletion of CL wasfaster in spleen. CL was not detected (<0.7μg/kg) in spleen on day3after withdrawal. Therefore, eyecan be used to as a target tissue to monitor and confirm the illegal use of CL in mutton sheep.(3) The prediction models of CL residue in principal tissues of ovine were studied. The study tried tofind the function relationship between CL residue concentration in principal tissues and duration ofwithdraw. The relative coefficients of prediction model regress equations fitted using SPSS17.0software with CL residue concentration in principal organ with time as variable factor. There was nosignificant relationship found between the predict value and calculated value according the equations(P>0.05). The residual predictive models of CL residue was fit the practical condition.(4) The analysis evaluation of uncertainty of CL content measurements in ovine eye was determined byLC-MS/MS．The mathematical model was established by using experimental data and all uncertaintycontributions were evaluated, which were used for calculation of the combined standard uncertainty andthe expanded uncertainty. The combined standard uncertainty was u（Qx）=3.4μg/kg. If coveragefactor k was2，the expanded uncertainty was U（P=95%）=2×u（Qx）=6.8μg/kg．The result of themeasurement was denoted as63.4±6.8μg/kg. As a result, the concentration of sample solution, whichwas gained from standard curve was the biggest factor for the uncertainty in measurement, the secondwas the constant volume and the repetition of measure, whereas, the uncertainty from electronic balancecould be ignored. |
PDF Full Text Request