Residues of prohexadione calcium in potatoes determined by HPLC and UPLC-MS/MS
[Aims]The aim of this study is to establish reliable high-performance liquid chromatography(HPLC)and ultra-performance liquid chromatography-tandem mass spectrometry(UPLC-MS/MS)methods for detecting prohexadione calcium residues and investigate its degradation dynamics and final residue levels in potatoes.[Methods]For the HPLC method,potato samples were extracted with a mixture of acetonitrile and 0.1％ of phosphoric acid aqueous solution and purified by C18 column,and then analyzed by HPLC with a DAD detector.Furthermore,we also explored the UPLC-MS/MS analysis method,where potato samples were extracted with a mixture of acetonitrile and 0.1％ of formic acid aqueous solution,purified by C18 column,and then analyzed with UPLC-MS/MS.At last,we explored the residual degradation dynamics and final residue of prohexadione calcium in potatoes under different application times.[Results]For the HPLC detection method,within the concentration range of 0.05 to 5.0 mg/kg of prohexadione calcium added into potatoes,the average recovery rate was 75％ to 91％ ,with a relative standard deviation(RSD)of 1.0％ to 7.0％ ,and a limit of quantification(LOQ)of 0.05 mg/kg.For the UPLC-MS/MS detection method,within the concentration range of 0.01 to 1.0 mg/kg of prohexadione calcium added into potatoes,the average recovery rate was 82％ to 90％ ,with an RSD of 3.0％ to 12.0％ ,and an LOQ of 0.01 mg/kg.The results indicated high accuracy and sensitivity of the two detection methods.Additionally,the results showed that the residual degradation dynamics of prohexadione calcium in potatoes did not conform to the first-order kinetic equation,and the accumulated final residues were detected,with the maximum value of 0.1131 mg/kg which was lower than the maximum residue limit(MRL)of 0.2 mg/kg stipulated in South Korea.[Conclusions]HPLC and UPLC-MS/MS methods for the determination of prohexadione calcium in potato were established,and their sensitivity,accuracy and precision were in accordance with the requirements of pesticide residues analysis.The final residue of prohexadione calcium in potato is lower than the maximum residue limit of South Korea,which provides a reference for the application of prohexadione calcium in potato and the establishment of maximum residue limit in China.
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