原子荧光光谱法测定当归补血汤中的微量硒

采用氢化物发生-原子荧光光谱法测定当归、黄芪以及两种药材以不同配伍形式的水煎液中的硒量。比较了不同提取方法及磷脂类化合物对水煎液中硒溶出的影响。结果表明,氢化物发生-原子荧光光谱法测定硒的方法的回收率为93.8%~95.0%,且当归∶黄芪为1∶5配比时的水煎液中硒溶出率高于1∶1配比,证实了当归补血汤经典配方的合理性,为其临床疗效提供了有效依据。     

氢化物发生-多接收杯电感耦合等离子体质谱同位素稀释法测定硒同位素

使用改进的巯基棉分离流程和74 硒-77 硒双稀释剂, 在氢化物(HG)-多接收器电感耦合等离子体质谱仪(MC-ICP-MS)实现了高精度硒同位素组成的测定.巯基棉用于分离样品基质中的硒, 随后使用HNO3 H2O2消除干扰的有机质, 74 硒-77 硒双稀释剂校正样品分离和质谱测定过程中的硒同位素质量分馏.硒标准溶液NIST SRM3149和MH495几个月的测定表明,该方法的外精度为0.1‰(2σ),样品的外精度为0.15 ‰～0.2‰(2σ).以TCF分离硒的平均回收率85%计算, 最小硒需要量为20 ng. 实验结果以相对于NIST SRM3149的δ82/76 Se表达, δ82/76MH495/SRM3149＝-3.44±0.1‰(2σ), 优于已发表的数据δ82/76MH495/SRM3149＝-3.04±0.5‰.测定样品的δ82/76SRM3149为-13.53 ‰～11.37‰,为硒同位素在环境、农业、生命和地球科学中的拓展应用与发展奠定了基础.     

Perfluoroalkyl Selenoxides,Selenones and Selenoximines: General Preparation and Properties

A selective access to perfluoroalkyl selenoxides, via Oxone® as oxidant or to selenones by using a Polyoxometalate-based Ionic Liquid (POM-IL) as a catalyst for the oxidation step is described. The reaction works with various perfluoralkyl chains and substituents with satisfactory to excellent yields. A two-step one-pot reaction from selenocyanates was performed to gain access to perfluoroalkyl selenoxides. The previously unknown perfluoroalkyl selenoximines family was also prepared with good yields. Having unlocked two strategies for the synthesis of fluoroalkylated Se^IV and Se^VI compounds, we then evaluated the Hansch-Leo lipophilicity parameters of these groups. Finally, asymmetric aryl perfluoroalkyl selenoximines were resolved to determine their absolute configurations.     

原子荧光光谱法测定区域地球化学调查样品中硒的干扰校正

氢化物发生-原子荧光光谱法(HG-AFS)是测定土壤样品中硒(Se)的理想方法，常用SePb合金材质的空心阴极灯为激发光源，无色散系统的AFS测硒时存在铅的光谱干扰，但尚未引起广泛关注。本文研究了高浓度Pb对硒测定的影响，并提出一种干扰校正的方法，可对检测结果进行有效校正。同时对还原剂浓度和消解酸的比例进行了优化，在2~40 ng/mL范围内获得Se标准曲线r2=0.9989，检出限为0.0023 ug/g，方法精密度为2.9-9.8%，准确度ΔlogC小于0.035。对南疆铁门关区域地球化学调查样品进行了测定，校正后Se的检测结果合格率为94.0%。此方法具有操作简单、准确高效，能够有效的校正样品中高浓度Pb的干扰，适合于大批量区域地球化学调查样品的检测。     

Retention mechanism of calcium ferrite and compositions of ash on selenium during chemical looping gasification

Selenium pollution by coal utilization is of increasing concern. Calcium-iron (Ca–Fe) oxygen carriers (OCs) and alkali metal ions have strong inhibitory effects on selenium, which can reduce the emissions of selenium vapor. The retention mechanisms of selenium by Fe₂O₃, CaFe₂O₄, Ca₂Fe₂O₅ and bottom ash are investigated during chemical looping gasification (CLG). Iron-based OC can oxidize H₂Se(g) to SeO₂(g); furthermore, lattice oxygen is released by Fe₂O₃, contributing to the formation of an Fe–O–Se structure to retain selenium and form selenite. Because calcium ferrite is poorly oxidizing, it cannot oxidize H₂Se(g), but the CaO produced when OCs are reduced can react with H₂Se(g) to form CaSe(s), and this process can be promoted by H₂S(g). The best retention rates reached 32.301% when Ca₂Fe₂O₅ was used. In the cyclic experiment, the selenium retention of the bottom ash gradually increases. Alkali metal ions in bottom ash are the main factor in retaining selenium. Ca²⁺ and Mg²⁺ do not easily vaporize due to their high melting points; therefore, their selenium retention is significantly better than that of K⁺ and Na⁺. This research provided a new idea for the removal of selenium by using OCs and bottom ash particles during CLG.     

Interfacial Self-assembly of Chiral Selenide Nanomembrane for Enantiospecific Recognition

Here, we report the synthesis of chiral selenium nanoparticles (NPs) using cysteine and the interfacial assembly strategy to generate a self-assembled nanomembrane on a large-scale with controllable morphology and handedness. The selenide (Se) NPs exhibited circular dichroism (CD) bands in the ultraviolet and visible region with a maximum intensity of 39.96 mdeg at 388 nm and optical anisotropy factors (g-factors) of up to 0.0013 while a self-assembled monolayer nanomembrane exhibited symmetrical CD approaching 72.8 mdeg at 391 nm and g-factors up to 0.0034. Analysis showed that a photocurrent of 20.97±1.55 nA was generated by the D-nanomembrane when irradiated under light while the L-nanomembrane generated a photocurrent of 20.58±1.36 nA. Owing to the asymmetric intensity of the photocurrent with respect to the handedness of the nanomembrane, an ultrasensitive recognition of enantioselective kynurenine (Kyn) was achieved by the ten-layer (10L) D-nanomembrane exhibiting a photocurrent for L-kynurenine (L-Kyn) that was 8.64-fold lower than that of D-Kyn, with a limit of detection (LOD) of 0.0074 nM for the L-Kyn, which was attributed to stronger affinity between L-Kyn and D-Se NPs. Noticeably, the chiral Se nanomembrane precisely distinguished L-Kyn in serum and cerebrospinal fluid samples from Alzheimer's disease patients and healthy subjects.