A rapid method with ultra‐high‐performance liquid chromatography–tandem mass spectrometry for simultaneous determination of five type B trichothecenes in traditional Chinese medicines

A speedy and selective ultra‐HPLC‐MS/MS method for simultaneous determination of deoxynivalenol (DON), 3‐acetyldeoxynivalenol (3‐ADON), 15‐ADON, nivalenol and fusarenon X in traditional Chinese medicines (TCMs) was developed. The method was based on one‐step sample cleanup using reliable homemade cleanup cartridges. A linear gradient mobile‐phase system, consisting of water containing 0.2% aqueous ammonia and acetonitrile/methanol (90:10, v/v) at a flow rate of 0.4 mL/min, and an Acquity UPLC HSS T3 column (100 mm×2.1 mm, 1.8 μm) were employed to obtain the best resolution of the target analytes. [¹³C₁₅]–DON was used as the internal standard to accomplish as accurate as possible quantitation. The established method was further validated by determining the linearity (R²≥0.9990), sensitivity (LOQ, 0.29–0.99 μg/kg), recovery (88.5–119.5%) and precision (RSD≤15.8%). It was shown to be a suitable method for simultaneous determination of DON, 3‐ADON, 15‐ADON, nivalenol and fusarenon X in various TCM matrices. The utility and practical impact of the method was demonstrated using different TCM samples.     

铁苯基膦配合物均相催化乙酰丙酸乙酯与甲酸反应转化为γ-戊内酯的分子机制

本文基于密度泛函理论,计算了Fe(CF3SO3)2/PP3催化乙酰丙酸乙酯与甲酸反应转化为γ-戊内酯的反应机理。分析了单重态和三重态反应路径的热力学和动力学性质,结果表明除了预催化剂活化出现势能面交叉外,反应主要在三重态势能面上进行,包括以下几个步骤：甲酸盐配位方式重置,β-H消除得到活性催化剂[FeH(PP3)]+,接着乙酰丙酸乙酯的羰基碳和羰基氧接连被质子化得到中间体4-羟基戊酸乙酯,最后质子化的反离子CF3SO3H作为氢转移梭子协助分子内脱醇—关环生成目标产物γ-戊内酯。进一步探讨不同金属苯基膦配合物的催化活性,证实金属适宜的配位能力是筛选催化剂的关键。理论计算结果为优化设计高性能的生物质转化催化剂提供一定的理论指导。     

Analysis of ochratoxin A and ochratoxin B in traditional Chinese medicines by ultra-high-performance liquid chromatography–tandem mass spectrometry using [C20]-ochratoxin A as an internal standard

The paper reported a reliable analytical method for simultaneous determination of ochratoxin A (OTA) and ochratoxin B (OTB) in traditional Chinese medicines (TCMs) by ultra-high-performance liquid chromatography–tandem mass spectrometry (UHPLC–MS/MS). The development of the method and investigations on the matrix influence were described in particular. The matrix effects were thereby minimized by using a reliable internal standard and a simple sample pretreatment. The established method was further validated by determining the linearity (R² ≥ 0.9990), average recovery (86.3–114.2%), sensitivity (limit of quantitation 0.03–0.19 ng mL⁻¹) and precision (relative standard deviation ≤ 13.1%). It was shown to be a suitable method for simultaneous determination of OTA and OTB in various TCMs. Finally, a total of 51 TCMs widely used in China were screened for OTA and OTB with the proposed method. The results showed that only 4 samples were contaminated with ochratoxins at low levels, indicating that it was low risk of ochratoxins to consumers who occasionally used TCMs.     

Zr基载体负载Pd催化剂用于贫燃天然气汽车尾气净化

 采用共沉淀法制备了 ZrO2, Y0.1Zr0.9Ox, Ce0.1Zr0.9Ox 和 Al0.1Zr0.9Ox 系列 Zr 基载体, 并用 N2 吸附-脱附和 X 射线衍射对其进行了表征. 再以此为载体, 采用浸渍法制备了整体式负载 Pd 催化剂, 催化剂涂层的涂覆量为 180 g/L 左右, Pd 含量为 1.25%. 测定了催化剂上 Pd 的分散度. 在模拟的贫燃天然气汽车尾气中考察了催化剂的活性, 并在尾气中有或无 SO2 存在的条件下比较了催化剂活性的差异. 结果表明, Y3+, Ce4+ 或 Al3+ 改性载体负载的 Pd 催化剂的耐硫性能明显改善; 无论尾气中是否存在 SO2, 以 Y3+ 或 Al3+ 改性载体负载的 Pd 催化剂的活性均明显高于 ZrO2 负载体的 Pd 催化剂.     

全自动食品甲醛分析仪的研制及应用

将超声提取、过滤和流动注射装置耦合,由自行设计的集成电路和软件控制,研制了一种全自动食品甲醛分析仪,实现了样品中甲醛提取—过滤—检测的连续自动化。利用在强碱性条件下,甲醛与间苯三酚快速发生显色反应,建立了测定食品中甲醛含量的测定方法,方法线性范围为0.5～20.0μg/mL,检出限为0.04μg/mL。用该法对水发海参、水发鸡爪、鹅肠和牛百叶样品进行了测定,测定结果在0.28～0.76μg/g之间(u=2,95%置信水平),样品加标回收率为88.7%～104%。该法适用于现场样品的快速测定。     

Application of quantitative structure-activity relationship to the determination of binding constant based on fluorescence quenching

Quantitative structure-activity relationship (QSAR) model was used to predict and explain binding constant (log K) determined by fluorescence quenching. This method allowed us to predict binding constants of a variety of compounds with human serum albumin (HSA) based on their structures alone. Stepwise multiple linear regression (MLR) and nonlinear radial basis function neural network (RBFNN) were performed to build the models. The statistical parameters provided by the MLR model (R²=0.8521, RMS=0.2678) indicated satisfactory stability and predictive ability while the RBFNN predictive ability is somewhat superior (R²=0.9245, RMS=0.1736). The proposed models were used to predict the binding constants of two bioactive components in traditional Chinese medicines (isoimperatorin and chrysophanol) whose experimental results were obtained in our laboratory and the predicted results were in good agreement with the experimental results. This QSAR approach can contribute to a better understanding of structural factors of the compounds responsible for drug-protein interactions, and can be useful in predicting the binding constants of other compounds.     

大型激光装置束间能量平衡能力综合分析方法

 针对大型激光装置输出能量平衡能力,建立了束间均方根分析方法。构建了大型激光装置的光束能量观测数据变换过程,得到服从近似正态分布的变换数据,从而建立简便的束间能量平衡能力的均方根计算方法;基于全控图和选图,针对装置能量平衡能力短期变化提出均方差控制图,并定义装置平均失效强度函数,用于描述装置整体的能量平衡能力长期变化趋势。通过对调试数据的分析,验证了综合分析方法的可视性和高效性。     

Cs(6D5/2)+H2→CsH[ X1Σ+(v,J)]+H转动分辨总截面的测量

利用泵浦-检测方法,在样品池条件下,研究了Cs(6D5/2)与H2反应碰撞传能过程。利用激光感应荧光（LIF）光谱技术,确定了CsH[X1Σ+(v,J)]振转能级上的布居分布,转动态分布与热统计分布基本一致.Cs激发态原子密度由激光能量吸收得到.记录A1Σ+(v',J+1)→X1Σ+(v,J)的时间分辨荧光,从荧光强度的对数值给出的直线斜率确定(v',J+1)→(v,J)的自然辐射率,结合(v,J)→(v',J+1)吸收系数的测量,得到反应生成物CsH[X1Σ+(v,J)]态的分子密度.由速率方程分析,给出反应截面(v,J),对J求和,得到(v)[10-16cm2单位]分别为（0.64±0.19）（v=0）和（0.58±0.17）（v=1）.     

氧分压对Mg掺杂ZnO薄膜结晶质量和光学特性的影响

利用脉冲激光沉积技术,通过改变沉积过程中的氧气压力,在蓝宝石(0001)基片上制备了一系列ZnMgO合金.通过X射线衍射、反射和透射光谱以及室温和变温荧光光谱,对薄膜的结构和光学性能进行了系统地表征,分析了工作气压对ZnMgO合金薄膜的结晶质量及光学特性的影响.研究结果表明:随着沉积环境中氧气压力的增大,ZnMgO薄膜的结晶质量下降,富氧环境下,与蓝宝石晶格平行的ZnO晶粒的出现是导致薄膜结晶质量下降的主要原因;相对于本征ZnO,不同氧气环境下沉积的ZnMgO薄膜的紫外荧光峰均出现了不同程度的蓝移.随着工 关键词： ZnO Mg掺杂 脉冲激光沉积 薄膜生长 光学特性     

Domain structure and optical property of epitaxial indium oxide film deposited on MgO(100) substrate

Indium oxide (In₂O₃) film has been deposited on MgO(100) substrate at 600 °C by metalorganic chemical vapor deposition (MOCVD). The crystal structure and epitaxial relationship of the sample were examined by X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM). The results showed a clear epitaxial relationship of In₂O₃(111)||MgO(100) with In₂O₃[011?]||MgO<072> or In₂O₃[01$\overline{1}$]||MgO<011>. A multiple domain structure was found inside the In₂O₃ film and a theoretical model clarifying the geometrical relationships between each domain and the substrate has been proposed. Scanning electron microscopy (SEM) micrograph showed that the main surface features were triangle-shaped grains on the film. The absolute average transmittance of the obtained film in the visible range was over 93%.