| Phenylethanolamine A (PHA), a new kind of β-agonists, has effect on promoting animal growthwhen added in the feed. The residue of β-agonists in tissue is harmful to the health of consumers.Ministry of Agriculture announces that PHA was forbidden to be used as feed additives in animal’s feedand water in2010. The objectives of this study were to develop an efficient method for the detection ofPHA in formula feed and tissues of growing-finishing pigs, and then the method was used to measurethe residues in growing-finishing pigs. So this study mainly includes four parts:(1) A rapid method for determination of PHA in formula feed by using ultra performance liquidchromatography (UPLC) has been developed. PHA in formula feed was extracted with methanolcontaining0.1%formic acid, then mix cation ionic exchange solid phase extraction cartridge were usedto clean up. The eluent was detected by UPLC coupled with PDA. A good linearity of PHA in feedsample was obtained in the range from0.10to20.0mg/kg. The linear relative coefficient of calibrationcurve (R2) was0.9945. The recovery in formula feed at different concentrations was above90.36%, andthe coefficient of variation (CV) was below5.98%.The limit of detection (LOD) was0.06mg/kg andthe limit of quantification (LOQ) was0.10mg/kg. The present method provides advantages of highsensitive, good precision, easy operation.(2) An analytical method for the determination of PHA in serum, urine, liver, lung, kidney andmuscle of growing-finishing pigs was established. After the procedure of enzymolysis, extraction, andsolid-phrase cleanup, the sample was determined by UPLC-MS/MS. The limit of detection (LOD) forserum, urine, liver, lung, kidney and muscle were0.2ng/mL,0.6ng/mL,0.6ng/ml,0.6ng/g,0.5ng/g,0.4ng/g,0.4ng/g, respectively; the limit of quantitation (LOQ) were0.3ng/mL,0.7ng/mL,1.4ng/g,0.9ng/g,0.8ng/g,0.9ng/g, respectively. The average recoveries ranged from81.19%-93.88%atfortified level of5-100ng/g PHA for serum,76.23%-98.65%for urine,82.43%-87.85%for liver,86.71%-88.19%for lung,77.50%-87.67%for kindey, and83.93%-85.75%for muscle.(3) Thirty six growing-finishing pigs were used to study the pharmacokinetics of PHA in serumand urine after effective anabolic dosage of15mg/kg and30mg/kg in feed were used for20daysconsecutively. The urine and blood samples were collected during and after the administration. Theresults show that the concentrations of PHA were low in serum whether during or after theadministration. The peak serum concentrations (8.51ng/mL) at the dose of15mg/kg was recorded onday6during the treatment, and the concentrations at the dose of30mg/kg peaked at15.50ng/mL onday12. The concentrations in serum declined quickly after withdrawal periods. The urineconcentrations were significantly higher than that in serum. The highest level of the two treatments inurine were166.60ng/mL and510.93ng/mL on day4during the treatment, and declined quickly afterwithdrawal periods.(4) Liver, lung, kidney and muscle samples were taken from three pigs which were eachslaughtered at d0, d3, d7and d14in withdrawal period. The results show that the residues of PHAwere found in all tissues above. The highest level was found in lung, and the lowest was in muscle. On day0after withdrawal, the residuals in lung, liver, kidney, muscle were68.53ng/g,17.03ng/g,12.77ng/g,7.3ng/g with15mg/kg dose group successively; those with30mg/kg dose group were416.3ng/g,26.75ng/g,41.6ng/g,15.04ng/g. PHA can neither be detected in the four kinds of tissues on day4afterwithdrawal with15mg/kg dose group, nor in kidney and muscle with30mg/kg dose group, whereas,the residuals in lung and liver were2.56ng/g,2.91ng/g respectively. |
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