气相色谱-质谱联用技术用于利尿剂的快速初筛和确证

利用微波辅助衍生及宏程序技术,对反兴奋剂条例的禁用列表中的一系列利尿剂药物进行了研究。建立了同时分析尿样中9种利尿剂的气相色谱-质谱联用(GC/MS)测定以及抽检尿样的初筛、确证的新方法。在GC-MS的选择离子监测(SIM)模式下,所建立定量方法的检出限为0.3~6.6μg/L;尿样中的提取回收率为37.6%~96.8%;RSD小于9.7%。由于采用了微波衍生样品前处理技术和宏程序数据处理方法,显著提高了分析效率,不但检测灵敏度完全能满足国际奥委会的要求,而且检测时间缩短3 h以上。方法成功地应用于口服吲达帕胺后尿样的检测,探讨了人尿中吲达帕胺代谢情况,有效进行兴奋剂监控提供了依据。     

石墨炉原子吸收法测定土壤中镉的测量不确定度评定

石墨炉原子吸收法测定土壤中镉的不确定度主要来源于称量样品、定容样品消解液、测定样品消解液中镉的质量浓度及测定土壤水分引入的不确定度。对各不确定度分量进行了计算,求得合成标准不确定度和扩展不确定度分别为0.0026、0.005mg/kg。镉测量不确定度的主要来源是测定样品消解液中镉质量浓度引入的不确定度。     

无焰燃烧烟密度标准物质的研制

介绍无焰燃烧烟密度标准物质的研制方法。选用合适的α-纤维素作为原材料,经打浆造纸后,作为标准物质候选物,经均匀性检验和稳定性考察合格后,对标准物质进行定值。在无焰燃烧条件下烟密度标准物质的标准值为175,扩展不确定度为8;校正烟密度标准物质的标准值为166,扩展不确定度为8。     

高度有序的二氧化钛纳米管阵列的制备及其光催化活性的研究

采用电化学阳极氧化法在钛表面构筑了一种结构有序、微米级的TiO₂纳米管阵列膜层. 考察了制备电压、氧化时间、溶液搅拌等实验参数对TiO₂纳米管阵列形貌和尺寸的影响. 应用SEM和XRD对膜层的形貌和晶型进行了分析和表征, 并通过TiO₂纳米管阵列膜对甲基橙的光催化降解, 研究了TiO₂纳米管阵列膜层结构与光催化活性的关系. 结果表明: 阳极电压和溶液搅拌对制备TiO₂纳米管阵列的结构起到关键的作用. 控制20 V电压制备的TiO₂纳米管阵列膜, 管长达2.6～3.3 μm, 经500 ℃热处理后具有最高的光催化活性, 其光催化性能明显优于一般的TiO₂纳米颗粒膜.     

中红外光谱法在无创血糖检测技术中的应用

构建了中红外无创血糖检测的实验方案,利用傅里叶红外光谱仪对葡萄糖溶液及手指进行了中红外光谱检测并进行分析,得到葡萄糖的中红外特征吸收峰在1000cm^-1附近,证实了中红外光谱在无创血糖检测中的可实现性,选择激光器和光导探测器进行特征峰处的光电检测实验,并得到了有效信号。     

Competitive Coordination of Chloride and Fluoride Anions Towards Trivalent Lanthanide Cations (La3+ and Nd3+) in Molten Salts

Molten salt electrolysis is a vital technique to produce high-purity lanthanide metals and alloys. However, the coordination environments of lanthanides in molten salts, which heavily affect the related redox potential and electrochemical properties, have not been well elucidated. Here, the competitive coordination of chloride and fluoride anions towards lanthanide cations (La³⁺ and Nd³⁺) is explored in molten LiCl-KCl-LiF-LnCl₃ salts using electrochemical, spectroscopic, and computational approaches. Electrochemical analyses show that significant negative shifts in the reduction potential of Ln³⁺ occur when F⁻ concentration increases, indicating that the F⁻ anions interact with Ln³⁺ via substituting the coordinated Cl⁻ anions, and confirm [LnCl_xF_y]^3−x−y (y_max=3) complexes are prevailing in molten salts. Spectroscopic and computational results on solution structures further reveal the competition between Cl⁻ and F⁻ anions, which leads to the formation of four distinct Ln(III) species: [LnCl₆]³⁻, [LnCl₅F]³⁻, [LnCl₄F₂]³⁻ and [LnCl₄F₃]⁴⁻. Among them, the seven-coordinated [LnCl₄F₃]⁴⁻ complex possesses a low-symmetry structure evidenced by the pattern change of Raman spectra. After comparing the polarizing power (Z/r) among different metal cations, it was concluded that Ln−F interaction is weaker than that between transition metal and F⁻ ions.     

A High-Efficiency Hematite Photoanode with Enhanced Bonding Energy Around Fe Atoms

Hematite nanoarrays are important photoanode materials. However, they suffer from serious problems of charge transfer and surface states; in particular, the surface states hinder the increase in photocurrent. A previous strategy to suppress the surface state is the deposition of an Fe-free metal oxide overlayer. Herein, from the viewpoint of atomic bonding energy, it is found that the strength of bonding around Fe atoms in the hematite is the key to suppressing the surface states. By treating the surface of hematite with Se and NaBH₄, the Fe₂O₃ transforms to a double-layer nanostructure. In the outer layer, the Fe−O bonding is reinforced and the Fe−Se bonding is even stronger. Therefore, the surface states are inhibited and the increase in the photocurrent density becomes much faster. Besides, the treatment constructs a nanoscale p–n junction to promote the charge transfer. Improvements are achieved in onset potential (0.25 V shift) and in photocurrent density (5.8 times). This work pinpoints the key to suppressing the surface states and preparing a high-efficiency hematite nanoarray, and deepens our understanding of hematite photoanodes.     

八元瓜环与氧氟沙星、氟罗沙星、加替沙星及司帕沙星相互作用的光谱法研究

用荧光光谱和紫外吸收光谱研究了八元瓜环与氧氟沙星、氟罗沙星、加替沙星及司帕沙星的相互作用体系的性质,考察了溶液酸度对作用体系的影响。在pH小于8.0的范围内,八元瓜环分别与氧氟沙星、氟罗沙星、加替沙星形成1∶1、与司帕沙星形成2∶1的稳定的主客体化合物;测定了不同pH时主客体相互作用的稳定常数均在103～104 L·mol-1(司帕沙星体系为1011 L2·mol-2)范围;同时测定了各作用体系的荧光发射和紫外吸收分析性能参数,药物客体的浓度线性范围达2～3个数量级,检测限为10-9～10-8 mol·L-1。     

3 MV多级多通道缩比开关自击穿特性

通过短接电极间隙,开展了3 MV多级多通道缩比开关不同间隙级数和单独触发间隙的自击穿特性分析,结果表明：自击穿电压随电极间隙距离不是线性增加,与Bradley经验公式存在差距。采用Ansoft软件模拟了实验开关不同级数的电场分布,得到不同级数开关电场分布的不均匀系数。结合缩比开关自击穿实验数据、Bradley经验公式和电场分布不均匀系数,在Bradley经验公式中加入开关作用时间因素和电场不均匀系数,得到一个Bradley外推公式,能较好地反应多级多通道气体开关的自击穿电压,使3 MV实际开关自击穿电压理论值与实验值误差减小到5%。