高效液相色谱-电感耦合等离子体质谱法分析食用菌中6种砷形态及其分布特征

建立同时测定食用菌中亚砷酸根、砷酸根、一甲基砷酸、二甲基砷酸、砷甜菜碱、砷胆碱6种砷形态化合物的高效液相色谱-电感耦合等离子体质谱分析方法。选择5 mmol/L和80 mmol/L(pH 8.0)碳酸铵溶液作为梯度洗脱的流动相，0.50 mol/L乙酸溶液作为提取剂，采用微波萃取的提取方式进行分析。6种砷形态化合物的质量浓度在0～100μg/L范围内与色谱峰面积线性关系良好，相关系数均大于0.999 0，亚砷酸根、砷酸根、一甲基砷酸、二甲基砷酸、砷甜菜碱、砷胆碱的检出限分别为0.04、0.05、0.08、0.07、0.05、0.09μg/L，定量限分别为0.13、0.15、0.20、0.20、0.16、0.28μg/L。样品加标回收率为88.3%～96.3%，测定结果的相对标准偏差为4.37%～8.98%(n=6)。采用该方法研究市售食用菌中砷形态分布特征，结果表明，不同类型食用菌中砷形态分布种类和含量不同，需综合无机砷和有机砷的含量评估食用菌中砷的危害性。     

氢化物发生-原子吸收光谱法测定大米中微量砷

砷是一种毒性很大的元素，对人的心肺、呼吸、神经、生殖、造血、免疫系统都有不同程度的损伤作用]。由于大气、地下水、土壤、肥料和农药等污染，砷会在粮食的可食部分积累，因此砷的测定已成为食品和环境监测的必测项目。测砷的常规方法有砷斑法、银盐法。目前，氢化物原子吸收光谱法，氢化物原子荧光法已有报道。本文采用氢化物发生—原子吸收光谱法测定大米中砷，本法具有灵敏度高，干扰少，操作简便等特点，结果满意。     

原子荧光光谱法测定尿中痕量砷

砷在自然界中对环境的污染较为普遍，砷中毒对人体健康危害很大，会影响细胞正常代谢，引发神经系统病变，含量高时可致人死亡，故对人体尿液中砷的测定很重要。测定痕量砷常用的方法为光度法，此方法测定时间长，手续繁杂，分析结果的重现性不是很好，本试验采用氢化物一原子荧光法，试样经消化后，在酸性条件下，加硫脲一抗坏血酸进行预还原，再用硼氢化钾将砷还原为AsH3，由载气导人石英炉原子化器进行原子化，在砷高强度空心     

高效液相色谱-电感耦合等离子体质谱法分析尿中6种砷形态

采用高效液相色谱-电感耦合等离子体质谱法（HPLC-ICP-MS）分析人尿中砷甜菜碱（AsB）、二甲基砷（DMA）、砷胆碱（AsC）、亚砷酸盐（As（Ⅲ））、一甲基砷（MMA）、砷酸盐（As(V)）6种砷形态。样品经水稀释后，采用Dionex IonPac As7阴离子交换色谱柱为分析柱，20 mmol/L碳酸铵（2%甲醇）和100 mmol/L碳酸铵（含2%甲醇）为流动相，梯度洗脱，HPLC-ICP-MS分析砷形态。6种砷形态在0～100μg/L范围内线性关系良好，相关系数（r）均大于0.999，检出限为0.05～0.15μg/L，不同浓度水平砷形态的相对标准偏差（RSD）均小于5.0%。3种不同浓度水平的加标回收率为91.8%～108%，有证标准物质“冷冻人尿中砷形态”（NIST SRM 3669）中5种砷形态的测定结果在标准值范围内。实验结果表明，该方法准确可靠、灵敏度高、分析时间短，适用于人尿中砷形态的分析测定。同时研究了食用不同含砷食物后尿中砷形态的种类，结果显示不同的含砷食品，其砷在人体内的代谢转化不同。     

燃煤电厂砷、硒、铅的排放与控制技术研究进展

煤炭是中国重要的能源资源，而中国煤中重金属砷、硒、铅含量较高，燃煤电厂已经成为重要的砷、硒、铅排放源之一。针对电厂燃煤带来严峻的砷、硒、铅污染问题， 本文首先介绍了燃煤释放的砷、硒、铅排放量大且危害性强，概述了世界各国关于重金属排放控制的相关政策法规，指出中国对燃煤重金属砷、硒、铅的排放控制势在必行；其次从煤中赋存形态、燃烧过程中的形态转化和质量分布三个方面阐释了燃煤过程中砷、硒、铅的迁移转化规律，重点描述了砷、硒、铅在颗粒物上的形态特征和尺度分布；最后综述了燃烧前、燃烧中和燃烧后对砷、硒、铅的排放控制技术，详述了吸附剂捕集和烟气净化装置协同脱除的研究进展，并论述了低低温除尘器和团聚技术对砷、硒、铅的强化脱除潜力。以期为燃煤电厂重金属砷、硒、铅超低排放的实现提供参考和指导。     

植物中砷的形态分析

应用离子交换树脂静态吸附和溶剂萃取相结合的分离技术，分析了植物中砷的四种形态化合物：无机三价砷和五价砷，一甲基胂和二甲基胂。并用石墨炉原子吸收光谱法（ＧＦＡＡＳ）测定其含量。文中采用ＨＣｌ浸提植物的砷，并对ＨＣｌ的浓度、体积以及浸提时间作了详细的探讨。用２０ｍＬ１ｍｏｌ／ＬＨＣｌ对１．０ｇ干植物２ｄ的浸出量与传统消化法总量的比值为０．８５－１．００。对浸出液进行形态分析，总砷回收率为８６％－９３％     

砷对植物生长的影响及植物耐砷机理研究进展

砷污染问题是全球面临的重大环境污染问题之一。综述了不同浓度砷及不同形态砷对植物生长的影响，耐砷植物及植物耐砷机理，指出了今后研究的主攻方向。     

改性凹凸棒的制备及对砷离子的吸附研究

针对日益严重的砷离子污染问题，本文采用灵敏简便的原子荧光分析法，探究了凹凸棒石粘土吸附剂对砷离子的吸附性能，测定了pH、吸附时间、砷离子的初始浓度等因素对凹凸棒石粘土负载铁氧化物对砷离子吸附能力的影响，并通过SEM、EDX、FTIR对所制得的吸附剂进行了表征研究，同时进行了吸附动力学和吸附等温模型的分析。研究结果表明，改性后的凹凸棒对砷离子的吸附性能有了显著提升，在较低浓度时吸附效率可达98%，该吸附符合Langmuir等温吸附模型和准二级动力学方程。     

红外光谱及其理论模拟在砷吸附过程中的应用

红外光谱技术具有分析速度快、分辨率高、灵敏度高、可以实时原位分析监测等优点。基于密度泛函理论对矿物吸附砷污染物体系红外光谱进行理论计算，分析对比红外光谱实测特征峰和理论计算特征峰，可以揭示砷吸附过程微观机制和表面化学形态。对红外光谱技术在水铁矿、赤铁矿、针铁矿等主要矿物吸附无机砷酸和有机胂酸的定性定量分析进行了综述，总结了红外光谱在无机和有机砷污染物吸附体系的定性定量研究及理论计算，为砷污染物精准检测分析和砷污染控制提供参考。     

超声辅助热酸提取液相色谱-电感耦合等离子体质谱联用法测定香辛料中6种砷形态

建立液相色谱-电感耦合等离子体质谱(LC-ICP-MS)联用法测定香辛料中6种砷形态(亚砷酸盐、砷酸盐、一甲基砷、二甲基砷、砷甜菜碱和砷胆碱)含量的分析方法。样品采用质量分数为1%的硝酸溶液在80℃条件下超声辅助提取10 min，使用PRP X-100阴离子色谱柱，以25 mmol/L NH₄H₂PO₄-乙醇(体积比为99∶1)溶液为流动相进行等度洗脱。6种砷形态的质量浓度在1.0～100μg/L范围内线性良好，线性相关系数为0.999 0～0.999 9，检出限为0.26～0.76 g/kg。肉蔻样品加标回收率为97.6%～104.7%,6种砷形态测定结果的相对标准偏差为1.73%～2.80%(n=6)。将所建方法应用于茴香、草果、胡椒、肉蔻、辣椒5种香辛料的测定，总砷提取率为96.7%～102.0%,6种砷形态检测回收比率为96.5%～103.9%。不同种类香辛料存在2～6种不同砷形态，其中无机砷含量为0.078～0.40 mg/kg，均占总砷的80%以上，砷酸盐为香辛料中砷的主要存在形态，参考国家标准食品中污染物限...     

二氧化碳和丙烯直接合成甲基丙烯酸的NiPMo/TiO2催化剂的研究

用溶胶-凝胶法以磷钼酸(MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2催化剂.使用ICP、 XRD、 TG-DTA、 IR、 TPD-MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能.杂多钼酸盐与TiO2通过O2-在TiO2表面发生了键合.在623 K下,杂多阴离子仍保持原有的Keggin结构.CO2在Lewis酸位Ni(Ⅱ)和Lewis碱位Ni-O-Mo的桥氧协同作用下生成CO2卧式吸附态Ni(Ⅱ)←O-(CO)←(O--Ni).丙烯有多种吸附态在催化剂上吸附.在563 K、 1 MPa和空速1500 h-1的反应条件下,丙烯的摩尔转化率为3.2%,产物MAA选择性为95%.     

Synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives

Different approaches for the synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives from simple amino acids have been investigated. A library of 33 precursors for the preparation of N-hydroxy pyrazinones was obtained in moderate to good yields.     

Toward new camptothecins. Part 6: Synthesis of crucial ketones and their use in Friedländer reaction

In the context of the preparation of camptothecin and luotonin A analogs, the synthesis of some key keto-precursors and their use in Friedländer condensation are described. This paper also focuses on the stability of these keto intermediates and emphasizes the major differences between indolizinones and pyrroloquinazolinones series. Noteworthy is also the report of some original structures isolated as by-products of some experiments.     

CoFe2O4自形成磁性液体场致结构化对磁化的影响

The Langevin paramagnetic theory can’t describe the relation between magnetization of ferrofluids and applied magnetic field. The structuralization of ferrofluids, which is considered the main influence factor of the magnetization, is regarded. The part of magnetization works is deposited when the structure is forming. This action influences the magnetization of ferrofluids directly or indirectly. On the base of the “compressing” model, the Langevin function that usually describes the magnetization of ferrofluid is modified, and a well-fitted curve is obtained. An equation of the relation between the equivalent volume fraction after being “compressed” and the intensity of magnetic field is discovered, which approximately describes the process of magnetization. The relation between the approximate initial susceptibility and the volume fraction can be obtained from modified formula.     

Highly regioselective Buchwald–Hartwig amination at C-2 of 2,4-dichloropyridine enabling a novel approach to 2,4-bisanilinopyridine (BAPyd) libraries

The highly regioselective Buchwald–Hartwig amination at C-2 of the cheap and readily accessible reagent, 2,4-dichloropyridine with a range of anilines and heterocyclic amines is described. This new methodology is robust and provides a facile access to 4-chloro-N-phenylpyridin-2-amines on 0.25 mol scale. These intermediates undergo a further Buchwald–Hartwig amination at higher temperature to enable rapid exploration of the chemical space at C-4 and to provide a library of 2,4-bisaminopyridines.     

KMnO4-mediated oxidative CN bond cleavage of tertiary amines: Synthesis of amides and sulfonamides

KMnO₄-mediated oxidative CN bond cleavage of tertiary amines producing secondary amine was introduced, which was trapped by electrophiles (acyl chloride and sulfonyl chloride) to form amides and sulfonamides. The reaction could take place at mild condition, tolerating a wide range of function groups and affording products in moderate to excellent yields.     

Chemistry of heterocyclic compounds at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, over 50 years (Review)

The review contains a concise historical account and information on the most significant researches undertaken by the staff at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences on the Chemistry of Heterocyclic Compounds. Dedicated to Academician of the Russian Academy of Sciences B. A. Trofimov on his 70th jubilee. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1443–1502, October, 2008.     

A general and convenient synthesis of 4-(tosylmethyl)semicarbazones and their use in amidoalkylation of hydrogen,heteroatom, and carbon nucleophiles

A general synthesis of previously unknown semicarbazone-based α-amidoalkylating reagents, 4-(tosylmethyl)semicarbazones, has been developed. The synthesis involved three-component condensation of semicarbazones of aliphatic or aromatic aldehydes with the same or other aldehydes and p-toluenesulfinic acid. The scope and limitations of this reaction were investigated. The compounds obtained were demonstrated to be an efficient α-(4-semicarbazono)alkylating agents. They were reacted with H- (sodium borohydride), O- (sodium methylate), S- (sodium phenylthiolate), N- (pyrrolidine, sodium succinimide), P- (trialkyl phosphites), and C-nucleophiles (sodium diethyl malonate) to give the corresponding products of the tosyl group substitution, 4-substituted semicarbazones, including analogues of nitrofurazone. Among the prepared compounds tested in vitro for antibacterial and antifungal activity, three nitrofuryl-containing semicarbazones exhibited high biological activities with minimum inhibitory concentration (MIC) values of 8–32 μg/mL.     

Sulfur-directed metal-free and regiospecific methyl C(sp3)–H imidation of thioanisoles

Regiospecific and direct imidation of the methyl C(sp³)–H bond of thioanisoles is realized under mild and metal-free conditions with N-fluorobis(benzenesulfonyl)imide as an oxidant and nitrogen source. Proposed mechanism suggests that thionium ion intermediates and a Pummerer-type reaction are involved. The imidation has advantages such as high step-economy, excellent functionality tolerance, and regiospecificity, giving structurally diverse imidation products.     

Synthesis of novel chiral bidentate hydroxyalkyl-N-heterocyclic carbene ligands and their application in palladium-catalyzed Mizoroki–Heck couplings and asymmetric addition of diethylzinc to benzaldehyde

A small library of new chiral bidentate hydroxyalkyl-imidazolium salts 1 is conveniently synthesized on multi-gram scale from inexpensive and commercially available chiral pool amino acids. The corresponding carbenes, generated by deprotonation of imidazolium salts 1, in combination with palladium(II) chloride were tested in the Mizoroki–Heck coupling reaction. The most significant results in terms of yields and reactivities were achieved with low catalyst loading. The catalytic activities of these imidazolium salts were also investigated in the asymmetric addition of diethylzinc to benzaldehyde. The use of MgO nanoparticles as an additive in conjunction with these ligands played a crucial role in increasing the efficiency of these reactions.