The laboratory established an efficient reversed-phase ultra-high-performance liquid chromatographyquadrupole time-of-flight mass spectrometry(UPLC-Q-TOF-MS)qualitative method for screening more than 2000 kinds of ris...The laboratory established an efficient reversed-phase ultra-high-performance liquid chromatographyquadrupole time-of-flight mass spectrometry(UPLC-Q-TOF-MS)qualitative method for screening more than 2000 kinds of risk substances(including local anesthetics,LAs)in cosmetics,which has been successfully applied in the analysis of actual samples.This work aims to develop a more convenient high performance liquid chromatography triple quadrupole mass spectrometry(HPLC-QQQ-MS/MS)method for the quantitative determination of LAs.Samples were ultrasonically extracted with methanol,separated on an Agilent Poroshell 120 EC-C18 column(2.1 mm×100 mm,2.7μm),and eluted with a gradient mobile phase consisting of 0.1%formic acid aqueous solution and methanol.Quantification was performed using the external standard method.The results show that all 23 LAs are effectively separated within 12 minutes,with good linearity in the corresponding concentration ranges and the correlation coefficients all greater than 0.99.The limits of detection(LOD)range from 0.0025 to 0.05μg/g,and the limits of quantification(LOQ)range from 0.01 to 0.1μg/g.The average recoveries of the 23 LAs in 5 blank cosmetic matrices are 80.68%-117.57%,with the relative standard deviations(RSDs)less than 5.98%.This method has good precision and high accuracy,and is suitable for the determination of LAs in 5 cosmetic matrices.展开更多
文摘The laboratory established an efficient reversed-phase ultra-high-performance liquid chromatographyquadrupole time-of-flight mass spectrometry(UPLC-Q-TOF-MS)qualitative method for screening more than 2000 kinds of risk substances(including local anesthetics,LAs)in cosmetics,which has been successfully applied in the analysis of actual samples.This work aims to develop a more convenient high performance liquid chromatography triple quadrupole mass spectrometry(HPLC-QQQ-MS/MS)method for the quantitative determination of LAs.Samples were ultrasonically extracted with methanol,separated on an Agilent Poroshell 120 EC-C18 column(2.1 mm×100 mm,2.7μm),and eluted with a gradient mobile phase consisting of 0.1%formic acid aqueous solution and methanol.Quantification was performed using the external standard method.The results show that all 23 LAs are effectively separated within 12 minutes,with good linearity in the corresponding concentration ranges and the correlation coefficients all greater than 0.99.The limits of detection(LOD)range from 0.0025 to 0.05μg/g,and the limits of quantification(LOQ)range from 0.01 to 0.1μg/g.The average recoveries of the 23 LAs in 5 blank cosmetic matrices are 80.68%-117.57%,with the relative standard deviations(RSDs)less than 5.98%.This method has good precision and high accuracy,and is suitable for the determination of LAs in 5 cosmetic matrices.
文摘由于超声回波信号受到噪声干扰或者到达时间混叠,故超声无损检测信号很难鉴别缺陷的大小.文中提出一种新的超声回波信号到达时间的识别方法.该方法首先把原始采集的回波信号进行经验模态分解,得到若干个固有模态函数,通过确定能量临界值,选择几个固有模态函数重构信号,重构信号的峰值包络表明了各个回波信号的到达时间.由衍射时差法(TOFD)实验信号验证了该方法的可行性及准确性.实验结果表明,可以识别的最小时间间隔为0.1μs,平均误差为80 ns.
