浓硫酸预蒸馏-连续流动分析法测定固体废物中总氰化物

固体废物样品过筛后用浓硫酸蒸馏处理,馏出液用SKALAR SAN++型连续流动分析仪进行分析,测定固体废物中的总氰化物含量。在最优条件下,馏出液中氰化物的质量浓度在0.00～100.00μg/L范围内与吸光度线性相关,相关系数为0.999 9。该方法检出限为0.08 mg/kg,固体废物样品测定值的相对标准偏差为3.3%～9.1%(n=6),加标回收率为97.0%。该方法适于测定固体废物中的氰化物含量。     

流动注射法测定鲜木薯中氰化物

建立稀氢氧化钠溶液超声提取鲜木薯中的氰化物,再用流动注射分析仪测定其含量的方法。将粉碎的样品以2 g/L氢氧化钠溶液提取,取上清液用流动注射分析仪进行定量分析。氰化物质量浓度在0~0.500μg/m L范围内与吸光度呈良好线性关系,线性方程为y=9.147×10~(–6)x–6.454×10~(–2),相关系数为1.000 0,方法检出限为0.05mg/kg,高、中、低3个浓度样品氰化物检测结果的相对标准偏差为1.6%~3.6%(n=6),加标回收率为96.8%~97.8%。采用该方法对木薯样品进行测定,测定结果满足国标GB 5009.36–2016食品中氰化物的检测误差要求。该方法线性范围宽,重复性好,可用于鲜木薯中氰化物含量的快速检测。     

连续流动-分光光度法测定固体废物中氰化物浸出毒性的研究

建立了一种利用连续流动-分光光度法测定固废中氰化物的浸出毒性的方法,当氰化物浓度在0~200μg/L范围内,校准曲线的相关系数r为0.9998;方法的检出限可以达到0.33μg/L;不同浓度样品测定的相对标准偏差低于2.6%,实际固体废物样品加标回收率为96%~103%,方法精密度良好并且准确度较高;通过实际样品测定结果比对,证明方法与传统国家标准方法测定结果有着较高的吻合度,具有良好的应用前景。     

连续流动分析法测定土壤中的挥发酚

建立了连续流动分析仪测定土壤中挥发酚含量的方法。称取5 g左右的土壤样品,以磷酸调节p H值为4,加入适量水并进行蒸馏,馏出液用连续流动分析仪测定挥发酚含量。在4.96~200μg/L范围内,挥发酚的质量浓度与相对峰高线性相关,线性方程为y=235.31x+51.6,相关系数r~2=0.999 8,挥发酚的检出限为1.24μg/L。取2种土壤样品分别进行6次平行测定,测定结果的相对标准偏差分别为1.52%,1.56%。对2种挥发酚标准样品进行测试,相对误差分别为1.90%,2.08%,加标回收率在87.8%~95.5%之间。该方法适合大批量样品的连续分析,且无需使用三氯甲烷,与传统方法相比更安全环保。     

正己烷萃取–连续流动光度法测定含油废水中的氰化物

建立在线蒸馏–连续流动分析仪检测含油废水中氰化物的分析方法。水样在p H12的碱性条件下,以正己烷为萃取溶剂两次萃取净化,去除废水中的油类干扰物。氰化物的质量浓度在0.005~0.500 mg/L范围内与响应峰高呈良好的线性,线性相关系数大于0.999,检出限为0.000 9 mg/L;对水样进行4个质量浓度水平的加标回收试验,回收率在85.0%~110.0%之间,测定结果的相对标准偏差为2.3%~5.6%(n=6)。该方法样品前处理简单、重现性好、检出限低,适用于含油废水中氰化物的测定。     

石墨消解–原子荧光法测定土壤中的汞和砷

采用石墨消解法对土壤样品进行预处理,用原子荧光光度法测定样品中汞和砷的含量。汞的质量浓度c在0.00~1.00μg/L范围内与荧光强度I线性相关,回归方程为I=849.47c–22.356,相关系数r2=0.999 9,检出限为0.001 8μg/g。砷的质量浓度在0.00~10.00μg/L范围内与荧光强度线性相关,回归方程为I=107.22c–28.994,相关系数r2=0.999 9,检出限为0.009 9μg/g。实际土壤样品5次平行测定汞和砷的相对标准偏差分别为6.2%~15.2%,0.8%~9.9%,用本法对黄土标准样品进行测定,测定结果在标准值允许范围内。     

区带流动分析技术测定水中氰化物

建立了区带流动分析技术快速测定水中氰化物的方法。用双气泡隔断方法实现完全显色反应,利用智能除泡技术排除气泡干扰,采用MobiChem便携式化学分析仪对环境水样中的氰化物进行测定。结果表明,氰化物的质量浓度在0～100μg/L范围内与吸光度呈良好的线性关系,相关系数为0.999 1,方法检出限为0.6μg/L。测定结果的相对标准偏差为2.6%～3.0%(n=7),样品加标回收率为96.1%～103.2%。该方法准确度高,检测耗时短,仪器携带方便,为现场监测及突发性污染事故的应急监测提供了一种新的手段。     

氢化物发生-原子荧光光谱法测定植物样品中的硒

本文应用氢化物发生-原子荧光光谱法对植物样品中硒总量的测定方法进行研究。优化了植物样品预处理,选取H2O2-HNO2(1∶5,V/V)体系微波消解;优化了测定中载流与还原剂的浓度,选定载流HCl浓度为15%,还原剂KBH4浓度为1.5%。该方法测定植物样品中的总硒,线性范围为0~100μg/L(r=0.9995),检出限为0.0906μg/L,回收率在90.0%~112.2%范围,精密度(RSD)小于0.39%。该方法操作简单、灵敏度高、检出限低,适合对植物样品中硒总量的分析测定。     

连续流动-分光光度法测定固体废物中氰化物浸出毒性的研究

建立了一种利用连续流动-分光光度法测定固废中氰化物的浸出毒性的方法,当氰化物浓度在0～200μg/L范围内,校准曲线的相关系数r为0.999 8;方法的检出限可以达到0.33μg/L;不同浓度样品测定的相对标准偏差低于2.6%,实际固体废物样品加标回收率为96%～103%,方法精密度良好并且准确度较高;通过实际样品测定结果比对,证明方法与传统国家标准方法测定结果有着较高的吻合度,具有良好的应用前景。     

超高效液相色谱–串联质谱法测定饮用水中微囊藻毒素

建立饮用水中微囊藻毒素(MC–RR,MC–LR)的超高效液相色谱–串联质谱检测方法。样品经PVDF针式过滤头过滤后直接进样,采用喷雾正离子源(ESI~+)和多重反应监测模式(MRM)测定。MC–RR的质量浓度在0.02~10.00μg/L范围内与色谱峰面积呈良好的线性,线性相关系数r~2=0.998 9,检出限为0.096μg/L,测定结果的相对标准偏差为6.6%~9.1%(n=7),加标回收率为99.0%~103.0%。MC–LR的质量浓度在0.1~20μg/L范围内与色谱峰面积呈良好的线性,线性相关系数r~2=0.999 2,检出限为0.188μg/L,测定结果的相对标准偏差为4.3%~10.0%(n=7),加标回收率为93.0%~114.0%。该方法灵敏度高、重现性好,可用于饮用水中微囊藻毒素的检测。     

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%.     

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.     

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.     

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.