微波消解-电感耦合等离子体发射光谱(ICP-OES)法测定茄子中矿物元素含量

采用微波消解HNO_3+H_2O_2湿法制取样品溶液,全谱直读电感耦合等离子体发射光谱(ICPOES)法同时测定茄子中K、Na、Mg、Al、Ca、B、Ba、Cr、Cu、Fe、Sn、Mn、P、Sr、Zn 15种矿物元素,实际样品测定结果显示,Al元素含量超过国家规定标准(≤100mg/kg),微量元素Ca含量相对较高。各元素的检出限为1.0~440μg/L,标准样品的加标回收率93.5%~109%,相对标准偏差在2.1%~6.5%(n=6)。实验方法简单、重现性好,可用于测定茄子样品中各矿物元素含量。测定结果为茄子的深入研究提供基础数据。     

电感耦合等离子体原子发射光谱法同时测定铜基低银焊料中的银、磷和锡

采用王水消解铜基低银焊料样品,选择Ag 328.0 nm、P 178.2 nm、Sn 189.9 nm作为分析线,建立了电感耦合等离子体原子发射光谱法(ICP-AES)同时测定铜基低银焊料中银、磷和锡元素的分析方法.在选定的试验条件下,方法检出限为0.002 4%~0.004 8%(质量分数),各元素校准曲线线性相关系数均大于0.999 5.按照试验方法测定样品,加标回收率为95%~103%,测定结果的相对标准偏差(RSD,n=10)均小于5%.     

ICP–AES法测定超高强度钢中的Al,Mn,Si,Ti

建立ICP–AES法测定超高强度钢中Al,Mn,Si,Ti 4种杂质元素的分析方法。研究了溶解条件试验及共存元素对4种分析元素的光谱干扰的情况,选择了Al 394.401 nm,Mn 257.610 nm,Si 251.611 nm,Ti 334.941 nm作为分析谱线。在选定的实验条件下,Al,Mn,Si,Ti的含量在0.001%~0.2%的范围内有良好的线性关系,相关系数均大于0.993,Al,Mn,Si,Ti的检出限为0.000 1~0.003 5 mg/L,加标回收率为94%~120%,测定结果的相对标准偏差小于10%(n=8)。该方法准确、快速,可用于超高强度钢中Al,Mn,Si,Ti的含量测定。     

电感耦合等离子体原子发射光谱法测定铅锌混合精矿中的Cu,Cd,Fe,As,Ag,Al6种元素

建立了电感耦合等离子体原子发射光谱法(ICP-AES)测定铅锌混合精矿中6种元素的定量分析方法。通过实验选择324.754,228.802,259.940,193.696,328.068,396.152nm分别作为Cu,Cd,Fe,As,Ag,Al的分析谱线,方法的检出限均小于0.010μg/mL。对铅锌矿标准样品进行分析,测定结果与标准值基本一致。方法的回收率在96%~104%,精密度实验结果表明,相对标准偏差(RSD,n=6)均小于4%,能满足日常分析对铅锌混合精矿中杂质元素的检测要求。     

电感耦合等离子体原子发射光谱法(ICP-AES)测定铅锌混合精矿中的Cu，Cd，Fe，As，Ag，Al 6种元素

建立了电感耦合等离子体原子发射光谱法(ICP-AES)测定铅锌混合精矿中6种元素的定量分析方法。通过实验选择324.754,228.802,259.940,193.696,328.068,396.152nm分别作为Cu,Cd,Fe,As,Ag,Al的分析谱线,方法的检出限均小于0.010μg/mL。对铅锌矿标准样品进行分析,测定结果与标准值基本一致。方法的回收率在96%~104%,精密度实验结果表明,相对标准偏差(RSD,n=6)均小于4%,能满足日常分析对铅锌混合精矿中杂质元素的检测要求。     

辉光放电质谱（GDMS）法校正高纯氧化铋中19种元素的相对灵敏度因子

采用标准溶液加入法往高纯氧化铋中加入混合标准溶液,烘干并研磨均匀,制备了5个高纯氧化铋的控制样品。再挑取适量的粉末样品压在高纯铟薄片上,建立了辉光放电质谱(GDMS)法校正高纯氧化铋中的Mg、Al、Ca等19种元素相对灵敏度因子的方法。实验考察了放电参数和制样面积对基体信号强度和稳定性的影响,优化后的辉光放电电流为1.8mA,放电电压为950V,压在铟薄片上的高纯氧化铋直径约为6～8mm。通过选择合适的同位素,在4000的中分辨率下测定即可消除质谱干扰。为了验证加标回收的准确性,采用电感耦合等离子体质谱(ICP-MS)法对控制样品进行测定,所有元素的加标回收率都在80%以上。采用GDMS法测定5个控制样品并结合ICP-MS法的测定值建立工作曲线,大部分元素的线性均达到0.995以上;除Al、Ga、Sb外,大部分元素的校准相对灵敏度因子(calRSF)和仪器自带的标准相对灵敏度因子(stdRSF)的比值都在1/2～2之间,说明GDMS的半定量分析不会有数量级的差别。但对于某些需要准确测定纯度的定量分析,则必须采用基体相匹配的RSF值进行校正。     

电感耦合等离子体原子发射光谱(ICP-AES)法测定车用尿素水溶液中的8种杂质元素含量

将1g尿素水溶液样品置于烘箱105℃下浓缩,在1 100℃马弗炉中加热灰化;取出冷却,使用盐酸(1+1)溶解灰分。采用Al 237.312nm、Ca 393.366nm、Cr 267.716nm、Cu 324.754nm、Fe 238.204nm、Mg 279.553nm、Ni 231.604nm、Zn 213.856nm作为分析线,建立了使用电感耦合等离子体原子发射光谱(ICP-AES)法测定尿素水溶液中铝、钙、铬、铜、铁、镁、镍和锌8种杂质元素的方法。结果表明,铝、钙、铬、铜、铁、镁、镍和锌的线性范围在0.02~2μg/mL时,校准曲线的线性相关系数均不小于0.999 5;方法中各元素的检出限为0.001~0.010μg/mL。将方法应用于尿素水溶液样品中8种杂质元素的测定,结果的相对标准偏差(RSD,n=7)均小于5.0%,加标回收率为91%~108%。方法可一次性完成对多种元素的测定,准确度、精密度较高,方法简便快速,适用于各级检验机构进行多批次、多项目产品的元素检测。     

微波消解-电感耦合等离子体质谱法测定砂仁中的铜、铅、砷、镉

建立了微波消解样品,电感耦合等离子体质谱法(ICP–MS)测定黔西南高砷土壤种植的砂仁中痕量铜、铅、砷、镉的分析方法。对微波消解条件进行了优化。为了避免消解试剂对质谱测定的干扰,选择硝酸–双氧水混合溶液(体积比为3∶1)作为微波消解试剂,采用ICP–MS测定消解液中铜、铅、砷、镉的含量。利用校正方程对砷、镉的质谱干扰进行校正。铜、铅、砷、镉4种元素的线性相关系数均大于0.999 2,检出限分别为0.073,0.048,0.39,0.062μg/L,测定结果的相对标准偏差小于4.5%(n=5)。各元素的加标回收率在96.0%～105.0%之间。该方法样品处理快速、简单,溶解率高,测定结果准确、可靠,适用于成批量砂仁样品中铜、铅、砷、镉微量元素的测定。     

电感耦合等离子体原子发射光谱法(ICP-AES)测定铜磁铁矿中的Al,Ni,Cu,Mg,Pb,Zn 6种元素

建立了电感耦合等离子体原子发射光谱法(ICP-AES)测定铜磁铁矿中Al,Ni,Cu,Mg,Pb,Zn6种元素的定量分析方法。通过实验选择396.152,216.555,324.754,285.213,220.353,213.857nm分别作为Al,Ni,Cu,Mg,Pb,Zn的分析谱线,方法的检出限均小于0.010μg/mL。与原子吸收光谱法进行对比,测定结果基本一致,方法的加标回收率在94%~105%,精密度实验结果表明,相对标准偏差(RSD,n=6)均小于5%,能满足日常对铜磁铁矿中杂质元素的检测要求。     

ICP-AES法测定烟花爆竹中禁限用药物

以5%HNO3处理烟花爆竹内药物样品,以ICP-AES法测定样品中K、Na、P、Mg、Ba、Cu、B、Sr、Sb、Ga、Ge、Al、Ti、Mn、Pb、As 16种元素。比较了不同酸、不同浓度时样品的处理方法,5%HNO3为最佳样品处理条件。对4个不同厂家产品进行了测定和加标回收研究,测定结果的相对标准差小于5%(n=5),各元素的回收率在93.4%～114.3%之间。     

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%.     

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.     

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.     

Selective syntheses of 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones via temperature-dependent Rh(II)-carbenoid-mediated 2H-azirine-ring expansion

The Rh(II)-catalyzed reaction of 2-carbonyl-substituted 2H-azirines with ethyl 2-cyano-2-diazoacetate or 2-diazo-3,3,3-trifluoropropionate provides an easy access to 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones. These compounds can be selectively prepared from the same starting material using temperature as the only varied parameter. The 2-azabuta-1,3-diene intermediate, a common precursor for both heterocyclic products, isomerizes into 2H-1,3-oxazine under kinetic control, while 1H-pyrrol-3(2H)-one is the sole product of the reaction at elevated temperatures. According to DFT-calculations a one-atom oxazine ring contraction involving ring-opening to a 2-azabuta-1,3-diene intermediate, followed by a 1,5- and 1,2-prototropic shift leads to the consecutive formation of imidoylketene and azomethine ylide, which then further undergo cyclization to the pyrrole derivative.     

Copper catalyzed/mediated synthetic methodology for ebselen and related isoselenazolones

Scope of the copper catalyzed/mediated selenium-nitrogen coupling reaction has been studied for the synthesis of isoselenazolones. It is noticed that the 2-chloro, 2-bromo-, and 2-iodo-aryl amides substrates can be exploited in the selenium-nitrogen coupling reaction by employing 25-100 mol % of CuI/1,10-phenanthroline (L) and potassium carbonate as a base in DMF. Furthermore, electron rich 2-chloro-arylamides also underwent selenium-nitrogen coupling reaction to give biologically important selenium-nitrogen heterocycles. Also, copper-catalyzed selenium-nitrogen coupling reaction has been meticulously applied for the synthesis of diaryl diselenides having methoxy, amine, and amide functionality from respective aryl iodides in the presence of stoichiometric amount of succinimide as an external Se-N coupling partner.     

Knoevenagel condensation catalyzed by novel Nmm-based ionic liquids in water

A series of novel N-methyl morpholine (Nmm) based ionic liquids with 1,2-propanediol group were synthesized and used as catalysts for Knoevenagel condensation at room temperature in water. Under the effect of the catalyst, various aldehydes or aliphatic ketones could react with a wide range of activated methylene compounds well, including malononitrile, alkyl cyanoacetate, cyanoacetamide, β-diketone, barbituric acid, 2-arylacetonitrile and thiazolidinedione. Furthermore, most of the products could be separated just by filtrating and washing with water. Additionally, the catalyst is recyclable and applicable for the large-scale synthesis.     

Construction of polyheterocyclic spirotetrahydrothiophene derivatives via sulfa-Michael/aldol cascade reaction

A series of polyheterocyclic spirotetrahydrothiophene derivatives were obtained in moderate to excellent yields via a catalyst-free sulfa-Michael/aldol cascade reaction of chalcones 1 and commercially available 1,4-dithiane-2,5-diol 2 under mild conditions. We also present the first asymmetric sulfa-Michael/aldol cascade reaction of chalcones 1 and commercially available 1,4-dithiane-2,5-diol 2 with moderate to good enantioselectivities catalyzed by readily available chiral phase-transfer catalysts (PTCs).     

Suzuki-Miyaura reactions of the soluble guanylate cyclase inhibitor NS2028: a non-product specific route to C-8 substituted analogues

Both soluble guanylate cyclase (sGC) inhibitors ODQ 1 and NS2028 2 are synthesized via improved protocols. In the former case treating 3,4-dihydroquinoxalin-2(1H)-one oxime 8, which can be prepared in two steps from 1,2-benzenediamine, with 1,1′-carbonyldiimidazole (CDI) gives the dihydro-ODQ 10 that in the presence of KMnO₄ oxidises to give ODQ 1 in an overall yield of 46% starting from 1,2-benzenediamine. In the latter case, the synthesis affords NS2028 2 from 2-amino-4-bromophenol 3 in three steps with an overall yield of 85% and avoids the need for chromatography. Furthermore, Suzuki-Miyaura reaction conditions are described that enable the preparation of 8-aryl and 8-heteroaryl derivatives of NS2028 directly from NS2028 2. Finally, demethylation of the 8-(methoxyphenyl) substituted analogues afforded the 8-(hydroxyphenyl) derivatives 40-42. All new products are fully characterised.