基于氧弹燃烧-离子色谱法测定生活垃圾可燃组分中氯和硫的含量

采用氧弹燃烧法对垃圾样品干燥基进行前处理,用碳酸钠(24 mmol/L)和碳酸氢钠(30 mmol/L)以及过氧化氢(2.5%)为吸收液,并用离子色谱法对其处理后吸收液中氯离子和硫酸根含量进行测定,最后换算为样品中氯和硫的含量。氯和硫酸根质量浓度分别在1~50 mg/L与色谱峰面积呈良好的线性相关,其线性相关系数都大于0.999。样品中氯的加标回收率为96.5%~99.1%,硫酸根的加标回收率为92.5%~101%,测定结果中样品的相对平均标准偏差均小于3%(n=5),并用质控样品对方法进行了验证,结果表明样品的前处理方法简单、样品损失少、准确度高,适合于垃圾样品可燃组分中氯和硫含量的测定。     

自动快速燃烧炉-离子色谱联用技术检测水泥等建材中的氯

建立了一种全新的以燃烧方法处理固体样品的装置——自动快速燃烧炉(AQF)与离子色谱联用的技术,检测建筑材料中氯的方法.该方法将AQF的快速处理样品的能力和离子色谱的准确性好、灵敏度高的特点相结合,可以连续批量处理样品,平均在18 min之内完成一个样品的检测.方法的线性、重现性、检测限均令人满意.还进行了水提法处理待测样品,将其结果与AQF处理的结果相比较,结果表明AQF处理的方法具可行性.     

基于氧弹燃烧-离子色谱法测定生活垃圾可燃组分中氯和硫的含量

采用氧弹燃烧法对垃圾样品干燥基进行前处理,用碳酸钠(24mmol/L)和碳酸氢钠(30mmol/L)以及过氧化氢(2.5%)为吸收液,并用离子色谱法对其处理后吸收液中氯离子和硫酸根含量进行测定,最后换算为样品中氯和硫的含量。氯和硫酸根质量浓度分别在1～50mg/L与色谱峰面积呈良好的线性相关,其线性相关系数都大于0.999。样品中氯的加标回收率为96.5%～99.1%,硫酸根的加标回收率为92.5%～101%,测定结果中样品的相对平均标准偏差均小于3%(n=5),并用质控样品对方法进行了验证,结果表明样品的前处理方法简单、样品损失少、准确度高,适合于垃圾样品可燃组分中氯和硫含量的测定。     

离子色谱法测定甲醇和噻吩中硫、氯含量

建立了测定工业用甲醇和噻吩中硫、氯含量的离子色谱检测方法。样品经(700±25)℃灼烧后,残留物用蒸馏水洗涤,利用离子色谱仪进行分析。甲醇和噻吩中硫、氯检测结果的相对标准偏差为1.04%~1.26%,加标回收率为99.2%~101.2%。该方法操作简单,精密度和准确度高,可用于大部分可燃性有机化合物中硫、氯含量的检测。     

氧弹燃烧–离子色谱法测定电子电气产品中卤素

利用氧弹燃烧处理样品,采用离子色谱法测定电子电气产品中的卤素含量。在0.2~1.0 mg/L范围内,氟、氯、溴、碘离子的质量浓度与离子色谱峰面积呈良好的线性关系,线性相关系数均大于0.999,各离子加标回收率为90%~110%,测定结果的相对标准偏差不超过5.0%(n=6)。该方法快速、准确,可应用于电子电气产品中卤素的测定。     

动物源性食品中硫氯酚残留量的高效液相色谱-电喷雾串联质谱法测定

建立了高效液相色谱-串联质谱(HPLC-MS/MS)测定动物源性食品中硫氯酚的方法.对样品前处理方法进行了改进,并对HPLC-MS/MS检测参数进行了优化.均质后的样品直接用乙腈提取,正己烷除脂净化后,采用HPLC-MS/MS电喷雾离子源、多反应监测负离子模式扫描,选择m/z 357/163、357/194作为定性离子对,m/z 357/163作为定量离子对,采用外标法定量.硫氯酚标准液的工作曲线在1 ～110 μg/kg范围内呈线性,相关系数为0.999 0;方法检出限和定量下限分别为 0.5、2 μg/kg;硫氯酚在添加含量2 ～100 μg/kg范围内平均回收率为80% ～112%,相对标准偏差为1.8% ～7.1%.该法操作简便、灵敏度高、回收率好,适用于动物肌肉、内脏及牛奶等动物源性基质中硫氯酚残留量的检测.     

氧瓶燃烧-离子色谱法测定植株中硫和氯

采用氧瓶燃烧法对样品进行燃烧,然后用0.08mol.L-1碳酸钠-0.01mol.L-1碳酸氢钠-过氧化氢吸收液吸收释放出的氯化氢和三氧化硫,并提出了离子色谱法分离测定植株中硫和氯含量的方法。以Ionpac AS14A(4mm×250mm)离子交换柱,以0.008mol.L-1碳酸钠-0.001mol.L-1碳酸氢钠溶液为淋洗液等度洗脱。硫和氯的方法检出限(3S/N)分别为0.04mg.L-1和0.02mg.L-1。方法用于大米(GSB-1S)、黄豆(GSB-4S)、菠菜(GSB-6S)和圆白菜(GSB-5S)标准样品的分析,测定值与认定值相一致,硫和氯的相对标准偏差(n=5)分别为3.1%和4.2%,回收率分别为97.0%和93.8%。     

在线中和富集-离子色谱法测定高纯氢氧化钠中痕量阴离子

建立了在线中和、富集待测离子后用离子色谱对高纯氢氧化钠中痕量阴离子进行检测的分析方法。样品经超纯水溶解、稀释后直接进样。试样经外接纯水输送至In Guard H消除OH-基体干扰,然后经过富集柱浓缩待测阴离子,再经阀切换技术进入离子色谱系统,以淋洗液发生器产生的KOH为淋洗液,流速为1.0m L/min,采用Ion Pac AS11-HC分析柱分离后,电导检测器检测。结果表明,在0.1~10.0 mg/L的线性范围内,氯离子、硫酸根、氯酸根的线性相关系数分别为0.999 8,0.999 6和0.999 2。方法对于氯离子、硫酸根、氯酸根的检出限分别为0.03,0.07,0.06 mg/kg,加标回收率分别为92%~104%,91%~111%和92%~106%,相对标准偏差(n=7)均小于2.0%。     

多次高温裂解、富集-离子色谱法检测己内酰胺中的痕量氯

建立了多次高温裂解、富集-离子色谱检测己内酰胺(CPL)中痕量氯的分析方法。CPL样品在富氧环境下经3次高温(800℃)裂解后,痕量有机氯转化为氯气或氯化氢气体,经5 mL 10 mmol/L的NaOH溶液吸收、富集,然后转化为氯离子,在阴离子抑制电导检测模式下进行离子色谱分析,检测其中氯离子(Cl-)的含量。在优化的条件下,Cl-在0.05~1.0 mg/L范围内呈良好线性,相关系数为0.999 7,方法检出限为0.37μg/g。对0.8 mg/L的Cl-标准溶液连续进样7次,其保留时间、峰面积、峰高的RSD分别为0.04%、0.24%和0.20%;分别对CPL样品进行处理和检测,得到痕量氯含量的RSD为1.52%(n=4);Cl-标准溶液的转化率为93.3%~104.0%,CPL样品的加标回收率为95.3%~113.1%。该方法操作简单、前处理条件可控、重复性好、检出限低,可满足实际样品中痕量氯的检测。     

液相色谱-串联质谱法与气相色谱-串联质谱法测定茶叶中苦参碱残留量

建立了茶叶中苦参碱残留检测的两种前处理方法,比较了液相色谱-串联质谱(LC-MS/MS)与气相色谱-串联质谱(GC-MS/MS)检测茶叶中苦参碱残留量分析方法的适用性。结果表明,在添加标准样品10~100μg/kg 3个水平时,两种前处理方法的回收率和精密度无显著差别;GC-MS/MS和LC-MS/MS回收率分别为81%~85%、82%~86%,相对标准偏差(RSD)分别为4.6%~11.5%和2.9%~4.2%。结果表明两种样品前处理方法以及LC-MS/MS与GC-MS/MS检测均能满足茶叶中苦参碱残留量的测定,但采用前处理方法二,LC-MS/MS检测茶叶中苦参碱残留更具优势。     

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.