| (3-blockers are a class of drugs that selectively bind to ?-adrenergic receptors and antagonize the neurotransmitters' effects on ?-adrenergic receptor.Due to the certain sedative effect,they are often used to promote growth or anti-stress in animal husbandry,resulting in residuals in animal edible tissues and causing a threat to human health.To monitor the drug residues and to improve the quality of animal food,a method of simultaneous detection 9 ?-blockers(including carazolol,acebutolol,atenolol,betaxolol,labetalol,metoprolol,nadolol,penbutolol,propranolol)residues in bovine and porcine edible tissues was established.1.Establish the HPLC-MS/MS method for simultaneous determination of nine ?-blocker residues in bovine and porcine edible tissuesSample pretreatment and purification:the samples were homogenized and frozen,after that samples were thawed and hydrolyzed with ?-glucuronidase/arylsulfatase.The hydrolysates were extracted with acetonitrile,and then the extracts were purified by matrix dispersion solid phase extraction(MSPD).HPLC-MS/MS detection conditions:Chromatographic separation of 9 ?-receptor blockers was achieved using the Waters ACQUITY UPLC(?)HS T3(100 mm x 2.1 mm,1.8 um)at 40?.The mobile phase comprised of 0.1%formic acid aqueous solution and 0.1%formic acid acetonitrile in a gradient elution model pumped at a flow rate of 0.2 mL/min.A tandem mass spectrometer with an electrospray ionization source was used to perform the assay using.ESI source positive ion mode and MRM model was used for ionization and ion scan.The internal standard method was used to quantitation.Confirmation of the detection method:The coefficient of correlation was not less than 0.99 between 0.5?50?g/kg of the 9 ?-blockers.At the level of 2.5,5,25?g/kg for each ?-receptor blocker,the average recovery of 9 ?-blockers in bovine liver,muscle,kidney were 87.6%?112.2%,86.7%?104.6%,85.4%?108.5%;the intra-day relative standard deviation were 2.0%?12.2%,2.2%?12.2%,3.6%?12.6%;the inter-day relative standard deviation were 5.6%?15.1%,8.5%?13.0%,6.0%?15.8%.The average recovery of 9 ?-blockers in porcine liver,muscle,kidney were 84.4%?114.2%,87.1%?114.2%,86.1%?100.2%;the intra-day relative standard deviation were 2.0%?12.6%,3.0%?14.6%,2.0%?11.5%;the inter-day relative standard deviation were 4.8%?18.7%,4.2%?15.0%,2.9%?15.5%.The limit of detection(LOD)and the limit of quantification(LOQ)of 9 ?-blockers were 1?g/kg and 5?g/kg in bovine and porcine tissues respectively.2.Determination of 9 ?-blockers residues in milk by HPLC-MS/MSSample pretreatment and purification:the milk samples were frozen and thawed,then hydrolyzed and extracted with 2 ml of 15%trichloroacetic acid and 4 ml of acetonitrile.The extraction was purified with MCX column.HPLC-MS/MS detection conditions:The HPLC-MS/MS detection conditions was the same with the above-mentioned conditions.Confirmation of the detection method:At the level of 0.5,1,5?g/kg,the average recovery of each ?-blocker in milk were 87.6%?112.2%,the intra-day relative standard deviation were 2.0%?12.2%;the inter-day relative standard deviation were 5.6%?15.1%.The LOD and LOQ of?-blockers were 0.2?g/kg and 0.5?g/kg in milk respectively.In this study,the recovery rate of the nine ?-blockers in cattle and pig edible tissues and milk was higher than 85%at three spiked concentrations.The relative standard deviations were less than 20%intra-day and inter-day.The LOD and LOQ was lower than the maximum residue limits in the edible tissues of animals currently stipulated by the European Union and other countries.Therefore,the detection method is suitable for ?-blocker multi-residue detection in cattle edible tissues,pig edible tissues and milk. |
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