Determination of Dithiocarbamates in Foodstuffs by LC-MS/MS

通过优化质谱、液相色谱和萃取缓冲液等条件,建立了一种简单、快速、灵敏测定食品中二硫代氨基甲酸酯的方法。在优化条件下,代森锌(EbdC)、丙森锌(PbdC)的线性范围为2~100μg/l,相关系数均不小于0.997。在花椰菜、萝卜和豌豆中EbdC和PbdC的检出限(S/n>3)为2μg/kg;萝卜和豌豆中Eb-dC和PbdC的定量下限(S/n>10)为10μg/kg,而花椰菜中EbdC和PbdC的定量下限(S/n>10)为15μg/kg。在花椰菜、萝卜和豌豆基质中加标5~100μg/kg的EbdC和PbdC时,测定加标回收率为83%~96%,相对标准偏差为4.4%~10.5%,方法可满足定量分析的要求。A simple,fast and sensitive method was developed for the determination of dithiocarbamates,including tiezene(EBDC) and pestanal(PBDC),by optimizing the parameters of LC-MS/MS and extraction buffer.Under the optimized conditions,the calibration curves of EBDC and PBDC were linear in the range of 2-100 μg/L with correlation coefficients not less than 0.997.The limits of detection(LODs,S/N>3) of EBDC and PBDC were 2 μg/kg for cauliflower,turnip and pea,and the limits of quantitation(LOQs,S/N>10) of EBDC and PBDC were 10 μg/kg for turnip and pea,and 15 μg/kg for cauliflower.The recoveries in cauliflower,turnip and pea samples at spiked concentration levels of 5-100 μg/kg ranged from 83% to 96% with relative standard deviations(RSDs) of 4.4%-10.5%.The method could meet the requirement for the analysis of dithiocarbamates in foodstuffs.厦门市科技计划项目(3502Z20092009;3502Z20102013); 国家质检总局科技计划项目(2010IK162;2010IK192

Determination of fungicide anilinopyrimidine residues in food by series solid phase extraction-high performance liquid chromatography-tandem mass spectrometry

建立了食品中嘧啶胺类杀菌剂嘧霉胺、嘧菌胺及嘧菌环胺残留的串联固相萃取-液相色谱-串联质谱(HPlC-MS/MS)检测方法。胡萝卜、辣椒等样品经乙酸乙酯提取,石墨化炭黑-弗罗里硅藻土串联固相萃取柱(EnVI-CArb-flOrISIl SPE)净化后,在HPlC-MS/MS仪上进行检测分析,采用外标法定量。质谱分析采用电喷雾电离,正离子扫描,多反应监测模式。结果表明,柱净化后无明显的基质效应,嘧霉胺、嘧菌胺和嘧菌环胺在1~20μg/l内相关系数可达0.999 0以上,具有良好的线性关系;每种杀菌剂选择两个离子对,其中一组用于定量:嘧霉胺M/z 200.1/107.1,嘧菌胺M/z 224.0/106.0及嘧菌环胺M/z 226.0/108.1;另一组用于确证:嘧霉胺M/z 200.1/183.1,嘧菌胺M/z 224.0/131.1和嘧菌环胺M/z 226.0/133.1。样品中添加0.1、0.5、1.0μg/kg的标准品,其回收率为73.2%~98.7%,相对标准偏差(n=10)小于10%;嘧霉胺、嘧菌胺、嘧菌环胺的检出限(信噪比(S/n)=3)均为0.03μg/kg;嘧霉胺、嘧菌胺、嘧菌环胺的定量限(S/n=10)均为0.1μg/kg。实验结果表明,该方法提取效果好,具有良好的灵敏度、回收率和重复性。A high performance liquid chromatography-tandem mass spectrometry(HPLC-MS/MS) method was established for the determination of fungicide anilinopyrimidine residues including pyrimethanil,mepanipyrim,and cyprodinil in foodstuffs with series solid phase extraction(SPE).The food sample was first extracted with ethyl acetate,and then purified by an ENVI-Carb cartridge and a Florisil SPE cartridge.The analytes were determined by HPLC-MS/MS and quantified by external standard method.The mass spectrometric detection was operated with electrospray in positive ionization mode and the fungicide anilinopyrimidines were identified in multiple reaction monitoring(MRM) mode.The linear range of the method was 1-20 μg/L,with the correlation coefficient(r2) over 0.9990.The transitions of the precursor ions to two selected product ions were involved,in which one group for quantification were m/z 200.1/107.1 for pyrimethanil,m/z 224.0/106.0 for mepanipyrim and m/z 226.0/108.1 for cyprodinil,and the other group for identification were m/z 200.1/183.1 for pyrimethanil,m/z 224.0/131.1 for mepanipyrim and m/z 226.0/133.1 for cyprodinil,respectively.No significant matrix effect was found for spiked samples after the purification.The recoveries of the fungicide anilinopyrimidines spiked in food samples were 73.2%-98.7% at the spiked levels of 0.1,0.5,1.0 μg/kg.The relative standard deviations(RSDs) were less than 10%.The limits of detection(LODs) and limits of quantification(LOQs) were 0.03 μg/kg and 0.1 μg/kg for the three fungicides,respectively.The results showed that the proposed method is sensitive and accurate for the determination of fungicide anilinopyrimidines in foodstuffs.The method should be applicable for routine analysis of pyrimethanil,mepanipyrim,cyprodinil residues in foodstuffs.厦门市科技计划项目(3502Z20092009、3502Z20102013);国家质检总局科技计划项目(2010IK192

Prediction of Energy Resolution in the JUNO Experiment

International audienceThis paper presents the energy resolution study in the JUNO experiment, incorporating the latest knowledge acquired during the detector construction phase. The determination of neutrino mass ordering in JUNO requires an exceptional energy resolution better than 3% at 1 MeV. To achieve this ambitious goal, significant efforts have been undertaken in the design and production of the key components of the JUNO detector. Various factors affecting the detection of inverse beta decay signals have an impact on the energy resolution, extending beyond the statistical fluctuations of the detected number of photons, such as the properties of liquid scintillator, performance of photomultiplier tubes, and the energy reconstruction algorithm. To account for these effects, a full JUNO simulation and reconstruction approach is employed. This enables the modeling of all relevant effects and the evaluation of associated inputs to accurately estimate the energy resolution. The study reveals an energy resolution of 2.95% at 1 MeV. Furthermore, the study assesses the contribution of major effects to the overall energy resolution budget. This analysis serves as a reference for interpreting future measurements of energy resolution during JUNO data taking. Moreover, it provides a guideline in comprehending the energy resolution characteristics of liquid scintillator-based detectors

JUNO Sensitivity on Proton Decay p→νˉK+p\to \bar\nu K^+ Searches

The Jiangmen Underground Neutrino Observatory (JUNO) is a large liquid scintillator detector designed to explore many topics in fundamental physics. In this paper, the potential on searching for proton decay in $p\to \bar\nu K^+$ mode with JUNO is investigated.The kaon and its decay particles feature a clear three-fold coincidence signature that results in a high efficiency for identification. Moreover, the excellent energy resolution of JUNO permits to suppress the sizable background caused by other delayed signals. Based on these advantages, the detection efficiency for the proton decay via $p\to \bar\nu K^+$ is 36.9% with a background level of 0.2 events after 10 years of data taking. The estimated sensitivity based on 200 kton-years exposure is $9.6 \times 10^{33}$ years, competitive with the current best limits on the proton lifetime in this channel

JUNO sensitivity on proton decay p → ν K + searches*

The Jiangmen Underground Neutrino Observatory (JUNO) is a large liquid scintillator detector designed to explore many topics in fundamental physics. In this study, the potential of searching for proton decay in the $p\to \bar{\nu} K^+$ mode with JUNO is investigated. The kaon and its decay particles feature a clear three-fold coincidence signature that results in a high efficiency for identification. Moreover, the excellent energy resolution of JUNO permits suppression of the sizable background caused by other delayed signals. Based on these advantages, the detection efficiency for the proton decay via $p\to \bar{\nu} K^+$ is 36.9% ± 4.9% with a background level of $0.2\pm 0.05({\rm syst})\pm$$0.2({\rm stat})$ events after 10 years of data collection. The estimated sensitivity based on 200 kton-years of exposure is $9.6 \times 10^{33}$ years, which is competitive with the current best limits on the proton lifetime in this channel and complements the use of different detection technologies