Study On The Analytical Methods Of Acid Dyes In Meat Products

With the improvement of living level,people pay more and more attention to food safety.In recent years,some industrial dyes were found to be added into food illegally.According to the national standard(GB 2760-2011),most acid dyes are not included in the range of food additives,and not allowed to add into food.The analysis methods for basic dyes in food have been developed greatly,and some testing standards also have been published.However,study on analysis of acid dyes was very rare till now.Since some accidents of abusing acid synthesized colorants in meat products had been reported,it is very necessary to establish the method for the simultaneous determination of variety of acid dyes in the meat products.This work was focused on developing the methods for determination of 14 acid dyes in meat products by HPLC-DAD and UPLC-MS/MS.Some innovative achievements had been reached and listed as follows:(1)A reliable pretreatment method for meat product matrix was established.Some important factors were investigated in detail,such as extraction solvents,solid phase extraction cartridges,eluents,and so on.The samples were extracted with methanol-water(90:10,v/v),then cleaned up by Waters-WAX solid phase extraction cartridge and eluted by methanol containing ammonia water.At last,the eluent was concentrated and solved with initial mobile phase.(2)The conditions of HPLC-DAD were optimized.The analytes were separated on Inertsil ODS-SP column with gradient elution using acetonitrile containing 50%(v/v)methnol-ammonium acetate as mobile phase.The identification was achieved according to retention time and absorption spectrum.The linear ranges were 0.5 mg/L～20 mg/L with the good linear relation.LOD and LOQ were 4.5～12.0 μg/kg and 15.0～40.0μg/kg.Tests for recovery were made by the standard addition method at concentration levels of 40,80 and 200 μg/kg,and values of average recoveries were in the range of 75.39%to 98.36%,whose inter and intra RSD were 0.1%～3.5%and 0.4%～4.5%.(3)The conditions of UPLC/MS-MS were also optimized.The analytes were successfully separated on the Waters ACQUITY UPLC BEH C18 column with gradient elution using acetonitrile-ammonium acetate as mobile phase.The identification and quantifition were achieved by using ESI-MS/MS in negative ion mode and with multiple reaction monitoring(MRM).The linear ranges were 10 μg/L-100 μg/L with the good linear relation.LOD and LOQ were 1.5～2.5 μg/kg and 5～8 μg/kg.Tests for recovery were made by the standard addition method at concentration levels of 10,20 and 50 μg/kg,and values of average recoveries found were in the range of 70.33%to 97.66%,whose inter and intra RSD were 0.3%～4.8%and 0.7%～6.5%.(4)The developed analysis methods were successfully applied to 150 meat product samples,and about 4%samples were confirmed to be positive.In order to further confirmation,a method based on UFLC-IT-TOF-MS was established and presented,which was proved to be feasible and reliable.All in all,the developed method was sensitive,effective and reliable,and was suitable for determination and confirmation of 14 acid dyes added in meat products illegally.