固相萃取-HPLC法测定浓缩梨汁中噻菌灵、多菌灵的残留量

研究了一种可同时测定浓缩梨汁中噻菌灵和多菌灵残留量的固相萃取-高效液相色谱分析方法.浓缩梨汁样品与水按一定比例稀释后,经过调pH、离心、过滤,用混合相固相萃取小柱(Mixed-mode SPE)进行提取、净化,用配有二级管阵列检测器(DAD)的液相色谱仪检测,外标法定量.使用噻菌灵和多菌灵对照品进行添加回收率测定,结果显示本方法对噻菌灵的最低检出限为0.020 mg/kg,回收率为80.5%~84.3%;对多菌灵的最低检出限为0.020 mg/kg,回收率为83.2%~92.5%;测定的相对标准偏差均不大于5%.本方法简单、快速、准确,能满足常规噻菌灵和多菌灵残留量检测的需要.     

固相萃取-HPLC法同时测定浓缩柑橘汁中噻菌灵、多菌灵的残留量

建立了一种可同时测定浓缩柑橘汁中噻菌灵和多菌灵残留量的反相HPLC分析法。浓缩柑橘汁样品用水适当稀释后,经过调节pH值、离心、过滤,用混合相固相萃取小柱(m ixed-mode SPE)进行提取、净化,用配有二级管阵列检测器(DAD)的液相色谱仪检测,外标法定量。使用噻菌灵和多菌灵对照品进行添加回收试验,噻菌灵、多菌灵的回收率分别为80.8%~87.1%、82.9%~87.7%,二者的测定下限均为0.020 mg/kg,测定结果的相对标准偏差均不大于7.38%(n=10)。     

苹果中多菌灵、噻菌灵和甲基托布津的高效液相色谱法分析

建立了同时检测苹果中多菌灵、噻菌灵和甲基托布津残留量的高效液相色谱(HPLC)分析方法.样品经乙酸乙酯提取,旋转蒸发仪浓缩,氮气吹干甲醇定容后,采用配有二极管阵列检测器(DAD)的HPLC测定,外标法定量.在添加不同浓度的标准品时,多菌灵、噻菌灵和甲基托布津的添加回收率分别为87.7%～118.7%、72.8%～80.3%、64.0%～66.8%.方法对多菌灵、噻菌灵和甲基托布津3种农药的检出限较低,分别为0.134、0.230和0.250mg/L,可以满足苹果汁中多菌灵、噻菌灵和甲基托布津的残留限量检测要求.检测果皮样品中的农药残留量,多菌灵的残留量为7.24×10-2mg/kg,噻菌灵和甲基托布津未检出,低于国标中规定的残留限量标准.     

超高效液相色谱-串联质谱法快速测定浓缩果汁中噻菌灵和多菌灵的残留量

建立了同时测定浓缩果汁中噻菌灵和多菌灵残留的超高效液相色谱-串联质谱快速检测法。样品用乙酸乙酯提取,以ACQUITY UPLC BEH C18色谱柱(50 mm×2.1 mm, 1.7 μm)进行超高效液相色谱分离,以电喷雾电离串联质谱正离子多反应监测(MRM)模式进行测定,以基质匹配标准溶液外标法定量。结果表明:在试验条件下,噻菌灵和多菌灵在0.5~10 μg/kg范围内线性关系良好,相关系数大于0.99,不同基质中的检出限(S/N=3)范围为0.12~0.23 μg/kg。在0.5、1.0和5.0 μg/kg 3个水平下噻菌灵和多菌灵的加标回收率为76.98%~108.7%,相对标准偏差(RSD)为2.95%~9.99%。同时,本研究对浓缩果汁中噻菌灵和多菌灵残留检测的基质效应进行了考察。本方法具有操作简便、快速、准确的特点,可用于浓缩果汁中噻菌灵和多菌灵残留量的日常检测。     

浓缩刺梨汁中噻菌灵和多菌灵残留量的高效液相色谱法测定

研究了一种可同时测定浓缩刺梨汁中噻菌灵和多菌灵残留量的固相萃取-高效液相色谱法。浓缩刺梨汁样品与水按一定比例稀释后，经过调pH、离心、过滤，用混合相固相萃取小柱（Mixed—mode SPE）进行提取、净化，用配有二级管阵列检测器（DAD）的液相色谱仪检测，外标法定量。用噻菌灵和多菌灵对照品进行添加回收率测定，结果显示本方法对噻菌灵的测定低限为0．020mg／kg，回收率为77．5％～87．1％；对多菌灵的测定低限为0．020mg／kg，回收率为74．0％～96．3％；测定的相对标准偏差均不大于7．4％。本方法能满足常规噻菌灵和多菌灵残留量检测的需要。     

固相萃取-离子交换色谱法测定浓缩苹果汁中残留的苯菌灵、多菌灵、噻菌灵

建立固相萃取-离子交换色谱法测定浓缩苹果汁中苯菌灵、多菌灵和噻菌灵的残留量。样品直接用水稀释后,于80 ℃下将苯菌灵完全转化为多菌灵,再经SCX固相萃取柱富集,采用LC-SCX离子交换色谱柱(25 cm×4.6 mm,5 μm)分离,二极管阵列检测器检测,以0.1 mol/L KH2PO4溶液(pH 2.5)-乙腈(体积比为70 ∶30)为流动相,在1.0 mL/min下等度洗脱,于282 nm波长下检测。在0.02～2.0 mg/L范围内,多菌灵和噻菌灵的峰面积与其浓度呈良好的线性关系,最低检出限均可达到0.004 mg/kg,回收率为94.2%～100.4%,相对标准偏差低于4.2%。该方法简便、快速、灵敏、准确,可用于浓缩苹果汁中苯菌灵、多菌灵和噻菌灵残留量的检测。     

固相萃取-高效液相色谱法测定浓缩苹果汁中的多菌灵残留量

报道了固相萃取-高效液相色谱法测定浓缩苹果汁中多菌灵残留量的方法.样品经适量水稀释后,C18固相萃取柱提取净化,用V(甲醇)∶V(二氯甲烷)=1∶1淋洗,HPLC法测定.在添加水平为0.10,0.50,2.0 mg/kg时,多菌灵的回收率在92.6%～108.3%之间;RSD＜3% (n=6),检出限为0.02 mg/kg,该方法的测定结果满足农药残留量的检测要求.     

固相萃取-高效液相色谱法测定饮料中多菌灵和噻菌灵

本研究采用HiCapt CT固相萃取(SPE)柱对食品中的多菌灵和噻菌灵进行富集净化,建立了高效液相色谱-紫外检测法测定饮料中的农药多菌灵和噻菌灵残留的分析方法。多菌灵和噻菌灵的检出限分别为0.23μg/L、0.22μg/L,定量限分别为0.74μg/L、0.70μg/L,回收率分别为81.74%~87.45%、87.26%~94.22%。该方法日内和日间相对标准偏差(RSD)分别小于7.5%和8.7%。所建立的方法可以有效除去果汁中的基质干扰,同时具备简单、快速、灵敏的优点,可用于果汁中多菌灵和噻菌灵的检测。     

HPLC法同时测定苹果及浓缩苹果汁中吡虫清等4种农药的残留量

建立了反相高效液相色谱-双波长检测法同时测定苹果及浓缩苹果汁中多菌灵、噻菌灵、吡虫啉、吡虫清4种农药残留量的方法。苹果样品经乙腈提取,加水稀释,而浓缩苹果汁样品直接用体积分数20%乙腈稀释后,利用CH2Cl2液-液萃取净化。分析时用C18色谱柱分离,以乙腈-0.05%冰乙酸系统梯度洗脱,选择246 nm和280 nm双波长检测。该方法4种农药的线性关系良好(r≥0.9999),检出限均为0.002 mg/kg,加标回收率在84.3%~109.1%范围内,相对标准偏差为2.0%~5.4%。本方法能够满足农药残留检测要求。     

高效液相色谱法测定柑橘中多菌灵、噻菌灵、甲基硫菌灵和硫菌灵残留量

应用高效液相色谱法测定了柑橘中多菌灵、噻菌灵、甲基硫菌灵和硫菌灵的残留量。样品用乙腈提取后,经氨基活性碳复合固相萃取小柱净化处理,以甲醇-水混合溶液为流动相梯度洗脱,经ZORBAX Extend-C18(150 mm×4.6 mm,5μm)色谱柱分离,在267 nm波长处,用紫外检测器检测。4种菌灵农药的质量浓度在0.1~10.0 mg.L-1范围与其峰面积呈线性关系,检出限(3S/N)均为0.05 mg.kg-1。方法对多菌灵、噻菌灵、甲基硫菌灵和硫菌灵的平均回收率在75.0%~98.7%之间,相对标准偏差(n=7)在3.2%~14.3%之间。     

Determination and study on residue and dissipation of benazolin-ethyl and quizalofop-p-ethyl in rape and soil

A QuEChERS (quick, easy, cheap, effective, rugged, and safe) method for the determination of benazolin-ethyl and quizalofop-p-ethyl in rape and soil by high-performance liquid chromatography-tandem mass spectrometry has been developed in this study. The residue and dissipation of benazolin-ethyl and quizalofop-p-ethyl in rape and soil were determined with the developed method. The half-lives of benazolin-ethyl in rape straw and soil were 3.7–5.1 days and 14.3–26.3 days, respectively. The half-lives of quizalofop-p-ethyl in rape straw and soil were 5.0-6.1 days and 0.3–9.7 days, respectively. The residue of benazolin-ethyl and quizalofop-p-ethyl in rapeseed and soil were below the detection limit (i.e., 0.5?mg?kg^?1, the maximum residue level of European Union for quizalofop-p-ethyl).     

多环芳二酐型聚酯亚胺膜的透气性能

多环芳二酐型聚酯亚胺膜的透气性能李悦生，丁孟贤，徐纪平（浙江大学高分子科学与工程研究所，杭州，３１００２７）（中国科学院长春应用化学研究所）关键词聚醚酰亚胺，聚酯酰亚胺，膜，透气性通常的聚酰亚胺加工性能较差，在芳环二酐的苯环间引入醚键等柔性基团后，其...     

微量元素与疾病诊断治疗的研究现状及展望

对国内外微量元素与疾病的关系及其诊断治疗的研究现状及研究动向进行了综述，包括：微量元素与地方病、癌肿、心血管病、糖尿病、眼病、神经系统病等。参考文献72篇。     

Ferrocene and ferrocenium modified clays and their styrene and EVA composites

In this work, ferrocene- and ferrocenium-containing salts were employed to modify montmorillonite. X-ray measurements show an increase in the interlayer spacing upon clay modification, which means that the larger and more organophilic cations were inserted into the gallery space of montmorillonite. Attempts to prepare nanocomposites of polystyrene and ethylene vinyl acetate copolymers lead to immiscible systems; the morphology of these systems was elucidated with TEM, XRD and cone calorimetry. The thermal stability of the composites is greater than that of the virgin polymer.     

Synthesis and Optical and Redox Properties of Symmetric and Asymmetric BODIPYs

Herein, we present the synthetic route and the photophysical, electrochemical as well as laser properties of novel red‐emitting boron‐dipyrromethenes (BODIPYs) bearing arylethyne moieties. Such functionality is added along the main axis of the chromophore leading to single‐ and double‐substituted derivatives. The relationship between the dye structure and the lasing properties is studied in detail with the help of the photophysical and electrochemical properties as well as quantum mechanical simulations. The asymmetric substitution of the parent dye induces inhomogeneities in the charge distribution, which leads to an overall loss of the fluorescence capacity, mainly in polar media. Such non‐radiative deactivation processes can be softened by decreasing the electron‐donor ability of the substituent or even avoided by symmetrical substitution. Thus, grafting of the arylethyne moieties at the longitudinal axis of the indacene core results in an effective strategy to develop red‐edge BODIPYs with highly efficient and photostable laser emission.     

Conformations and steric and stacking interactions of trisubstituted ureas and thioureas with alkyl and phenyl groups

The monomeric ν(N—H) vibrations of various trisubstituted ureas of the R₂UPh type and -thioureas of the R₂TUPh type have been studied. The trans—out isomerism in the former and the trans—out—cis isomerism in the latter are discussed from the point of view of steric effect. The monomeric ν(N—H) vibrations of RPhUPh and RPhTUPh are also examined. The single band appearing in the spectrum of both ureas is characteristic of the cis form; this suggests the existence of phenyl—phenyl interaction (the stacking interaction proposed by Galabov et al. [10]). Behavior of ν(N—H) vibrations at several concentrations is shown to be clearly different in the three forms (trans, out and cis). The presence of the cis form is confirmed by solvent effect experiments.     

含茂基苯并三氮唑基镧系有机配合物的合成及表征

三茂基镧系化合物和苯并三氮唑在四氢呋喃中反应,合成了7个未见文献报道的含茂基苯并三氮唑基镧系有机配合物,经元素分析、IR和MS测定,从有关数据推测了这类配合物的可能结构。     

Ti-V基储氢合金及其氢化物的物相结构与组分优化设计

Ti-V基储氢合金在室温、常压下即可表现出良好的储氢特性,且质量储氢容量明显高于传统AB₅型储氢合金,从而在氢气的精制和回收、运输和储存及热泵等方面有较早的应用。 此外,在混合气体分离、核反应堆中处理氢的同位素、镍氢电池及燃料电池负极材料等方面也得到了广泛的研究与关注。 基于目前Ti-V基储氢合金的研究现状,概述了该类合金的优势、限制性因素(包括成因)及改性手段。 此外,为了进一步理解Ti-V基合金储氢机理、构建合金组分与储氢特性之间的对应关系,本工作重点围绕Ti-V基储氢合金及其氢化物的结构、组分优化设计展开综述,并对其未来研究方向做出展望。