HG-AFS同时测定扬州毛绒玩具中的可迁移元素汞和硒

采用了氢化物发生-原子荧光光谱法对扬州毛绒玩具中的汞(Hg)和硒(Se)进行同时测定。在0—10μg/L范围内汞和硒的浓度与荧光强度呈线性关系,相关系数分别为0.9999和0.9998,加标回收率分别达到88%—95%和92%—109%,汞、硒测定结果的RSD分别不大于3.83%和3.70%。     

双四极杆电感耦合等离子体质谱(ICP-MS/MS)法测定婴幼儿配方奶粉中的硒含量

应用电感耦合等离子质谱法测定婴幼儿配方食品中硒元素含量时,由于硒元素存在难电离、质谱干扰等原因往往导致硒元素测定含量偏高,方法通过含碳有机物增敏,不同分析模式去干扰从而建立能准确测量婴幼儿配方食品中硒元素含量的电感耦合等离子体质谱方法。试验方法采用分析不同含碳有机物如甲醇、乙醇、异丙醇、正丁醇的增敏效果,考察有机物浓度0%-10%范围内的影响,并研究标准模式（no gas模式）, 单杆氦气碰撞模式（He模式）,串联氦气碰撞模式（HeHe模式）、串联氧气反应模式（O2模式）等不同分析模式下的抗质谱干扰能力,确定婴幼儿配方奶粉中硒含量分析的最佳条件。结果表明具有最佳增敏效果的试剂为5%正丁醇,相较于其他分析模式,串联氧气反应模式检测婴幼儿奶粉质控样中的硒含量更加准确,该方法在0.50-10.00μg/L范围内呈现良好的线性关系(r2＞0.999),平均回收率为94.3~100.4%,精密度小于5%,方法检出限和定量限分别为0.1μg/100g和0.3μg/100g,与原子荧光分光光度法做t检验比较,各类市售婴幼儿配方食品中硒含量测定值无显著性差异(P＞0.05)。本方法操作简便、检出限低、检测结果准确,适合于婴幼儿配方食品中硒元素的准确测量。     

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.