高效液相色谱法同时测定水产品中6种喹诺酮药物的残留

建立用固相萃取-反相高效液相色谱法同时检测水产品中6种喹诺酮药物残留量的方法。通过对提取方法和C18固相萃取柱净化条件、色谱条件选择与优化、洗脱液浓度和用量的选择方面的研究,确定采用高效液相色谱分离、荧光检测器检测、外标法定量的分析方法。本方法对环丙沙星、恩诺沙星、氧氟沙星、诺氟沙星、噁喹酸、氟甲喹标准曲线的线性回归系数均在0.99以上,线性范围为0.02～2.0μg/mL。以3倍信噪比RSN计算,环丙沙星、恩诺沙星、诺氟沙星、氧氟沙星检出限为2μg/kg,噁喹酸、氟甲喹检出限为5μg/kg;以10倍信噪比RSN计算,环丙沙星、恩诺沙星、氧氟沙星、诺氟沙星的定量下限为5μg/kg;噁喹酸、氟甲喹的定量下限为10μg/kg。在南美白对虾、罗非鱼、鳗鱼、斑点叉尾鮰中进行这6种喹诺酮类药物加标回收率的验证实验,实验结果满意,回收率在78.8%～92.9%之间;相对标准偏差为2.97%～7.10%。说明本方法简单、灵敏,结果可靠,可用于水产品中环丙沙星、恩诺沙星、氧氟沙星、诺氟沙星、噁喹酸、氟甲喹的同时检测

高效液相色谱-串联质谱法测定水产品中玉米赤霉醇类激素药物残留量

文章建立用高效液相色谱-串联质谱法(HPLC-MS/MS)测定水产品中玉米赤霉醇类激素药物残留量的方法。用乙腈提取水产品中6种玉米赤霉醇类药物,正己烷脱脂,氨基固相萃取柱净化。采用电喷雾电离,负离子扫描,选择反应监测模式(SRM)监测,外标法定量。该法对6种玉米赤霉醇类药物标准曲线的线性回归系数均在0.99以上,线性范围0~25μg.kg-1,方法定量限1.0μg.kg-1。6种玉米赤霉醇类激素药物回收率75.9%~103.8%,相对标准偏差3.90%~13.5%。该法简单、灵敏,结果可靠,可满足实验室批量样品分析的需求

高效液相色谱—串联质谱法测定水产品中19种喹诺酮类药物残留量

建立用高效液相色谱-串联质谱法测定水产品中19喹诺酮类药物——氟甲喹、噁喹酸、诺氟沙星、依诺沙星、环丙沙星、培氟沙星、洛美沙星、丹诺沙星、恩诺沙星、氧氟沙星、沙拉沙星、司帕沙星、双氟沙星、西诺沙星、奥比沙星、麻保沙星、萘啶酸、氟罗沙星和吡哌酸残留量的方法。用酸化乙腈提取水产品中喹诺酮类药物,正己烷脱脂。采用电喷雾电离源(ESI),正离子扫描模式,选择反应监测模式(SRM)监测,外标法定量。该方法对19种喹诺酮类药物标准曲线的线性回归系数均在0.99以上,线性范围为2～200ng/mL,氟罗沙星和吡哌酸检出限为1.0μg/kg、定量限为2.0μg/kg,其余17种喹诺酮的检出限为0.5μg/kg、定量限为1.0μg/kg。19种喹诺酮类药物回收率在76.3%～108%之间,相对标准偏差为0.743%～13.1%。该方法简单、灵敏,结果可靠,可满足实验室批量样品分析的需求

A study on the distribution of polyploid loaches in China

Natural triploid and asexually reproducing clonal diploid loaches are found in Japanese populations of the loach, Misgurnus anguillicaudatus. The distribution of polyploid loaches in Chinese populations has not been studied except for a few cytogenetic studies that described the occurrence of polyploidy. In the present study, we examined the ploidy status of a total of 762 specimens collected from 29 localities in China by measurements of erythrocytic cell nucleus after the ploidy determination performed by chromosome counting and DNA content flow-cytometry in selected individuals. Among diploid, triploid and tetraploid individuals, significant differences were detected in major and minor diameters of nucleus, and also nuclear volume. A few triploid (3n) loaches were detected in relatively wide areas including Hohhot, Neimenggu (3.3%), Tianjin (5.3%), Hangzhou, Zhejiang (3.3%), Chibi, Hubei (3.3%), Honghu, Hubei (6.7%) and Shashi, Hubei (3.3%). However, tetraploid (4n) loaches were detected only in Chibi (3.3%), Honghu (16.7%), Shashi (3.3%) and Ezhou (5.0%) from Hubei province. These results indicate that there are several localities in China exhibiting relatively higher frequencies of polyploid loaches

A new method of fabricating three dimensional ( 3D) paper-based microfluidics chip by clips

提出一种利用回形针来制作三维微流控纸芯片的方法,能够适应多种不同的微流控纸芯片;利用自制的纸芯片比色检测装置,已用于牛血清白蛋白,Fe~(2+)的快速定量检测。牛血清白蛋白的线性范围是5~50μmol/L,检出限为0.13μmol/L,R~2=0.994。Fe~(2+)的线性范围是0.6~12μmol/L,检出限为0.15μmol/L,R~2=0.992。在所规定的范围内,都获得了较好的线性关系,验证了基于回形针的3D微流控纸芯片可用于实际样品检测的可能性

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