固相萃取-气相色谱/质谱选择离子检测法测定水中27种有机农药EI北大核心CSCD

采用固相萃取(SPE)技术,结合气相色谱/质谱(GC-MS)选择离子检测法(SIM)对水中27种有机农药进行提取、净化、浓缩前处理,实验优选出了分离效果较好的色谱柱VF-1701 ms(30 m×0.25 mm×0.25μm),优化了固相萃取及GC-MS的分析条件,建立了水样中7类27种有机农药的SPE-GC-MS/SIM分析方法。样品中各组分曲线相关系数R2均大于0.9981,检测限为0.015~0.054μg/L,平均加标回收率为72.8%~110.8%,相对标准偏差RSD为5.5%~16%。与传统方法相比,该法无需对有机污染物进行分类处理,可以同时快速测定7类27种有机农药。     

固相萃取-气相色谱/质谱选择离子检测法测定水中27种有机农药EI北大核心CSCD

采用固相萃取(SPE)技术,结合气相色谱/质谱(GC-MS)选择离子检测法(SIM)对水中27种有机农药进行提取、净化、浓缩前处理,实验优选出了分离效果较好的色谱柱VF-1701 ms(30 m×0.25 mm×0.25μm),优化了固相萃取及GC-MS的分析条件,建立了水样中7类27种有机农药的SPE-GC-MS/SIM分析方法。样品中各组分曲线相关系数R2均大于0.9981,检测限为0.015~0.054μg/L,平均加标回收率为72.8%~110.8%,相对标准偏差RSD为5.5%~16%。与传统方法相比,该法无需对有机污染物进行分类处理,可以同时快速测定7类27种有机农药。     

固相萃取-气相色谱/质谱选择离子检测法测定水中27种有机农药

采用固相萃取(SPE)技术,结合气相色谱/质谱(GC-MS)选择离子检测法(SIM)对水中27种有机农药进行提取、净化、浓缩前处理,实验优选出了分离效果较好的色谱柱VF-1701 ms(30 m×0.25 mm×0.25μm),优化了固相萃取及GC-MS的分析条件,建立了水样中7类27种有机农药的SPE-GC-MS/SIM分析方法。样品中各组分曲线相关系数R2均大于0.9981,检测限为0.015~0.054μg/L,平均加标回收率为72.8%~110.8%,相对标准偏差RSD为5.5%~16%。与传统方法相比,该法无需对有机污染物进行分类处理,可以同时快速测定7类27种有机农药。     

加速溶剂萃取同步净化-同位素内标-气相色谱-高分辨质谱测定水产品中32种多氯联苯

建立了加速溶剂萃取同步净化-同位素内标-气相色谱-高分辨质谱同时测定水产品中32种多氯联苯含量的方法。通过在加速溶剂萃取仪中加入2 g无水硫酸钠、1 g弗罗里硅土、50 g中性氧化铝作为吸附剂实现同步净化的效果，萃取溶剂为二氯甲烷-正己烷（1:1，v/v），萃取温度为100℃，循环2次。萃取结束后分别用0.5 mL浓硫酸净化两次，净化液浓缩定容后，采用气相色谱-高分辨质谱测定，同位素内标法定量。32种多氯联苯在0.1~20 μg/L范围内平均相对响应因子（RRF）的相对标准偏差（RSD）值（n=7）均小于15%，定量限（S/N=10）为0.3~1.9 ng/kg。在草鱼和海鲈鱼空白基质中做加标回收试验，添加水平为5、20和50 ng/kg，得到的平均回收率为71.9%~119.0%（n=6），RSD为3.5%~19.6%。该方法背景干扰低，灵敏度高，重现性好，回收率稳定，适用于水产品中多氯联苯的检测。     

气相色谱-串联质谱检测鹅组织中哌嗪残留

建立了鹅组织(肌肉、肝脏、肾脏以及皮肤和脂肪)中哌嗪残留的气相色谱-串联质谱检测法。鹅组织经加速溶剂萃取(ASE350),乙腈提取,过Strata-X-C固相萃取小柱净化后的样品在乙酸酐和三乙胺条件下衍生。衍生产物经气相色谱-串联质谱仪(GC-MS/MS)检测,色谱柱为TG-5MS Amine(30 m×0.25 mm i.d.,0.25μm),载气为氦气,进样口和检测器温度均为280℃。采用EI模式,SCAN和SIM扫描定性,Auto SRM结合外标法定量。哌嗪添加量在5.1~2.5×10~3μg/kg范围内,线性关系良好,相关系数为0.9995。在定量限(LOQ:5.1,5.2,5.2,5.2)~2.0×10~3μg/kg的加标水平上,鹅组织中哌嗪的平均回收率为85.2%~95.5%,相对标准偏差(RSD)为1.6%~4.7%,日内RSD为1.2%~5.3%,日间RSD为2.0%~7.7%。检测限(LOD)和定量限(LOQ)分别在1.4~1.6μg/kg(S/N≥3)和5.1~5.2μg/kg(S/N≥10)之间。方法适用于鹅组织中哌嗪残留的检测。     

气相色谱-串联质谱同位素内标法测定中草药中124种农药及其代谢物残留

建立测定中草药中124种农药及其代谢物残留的气相色谱-串联质谱(GC-MS-MS)方法。采用同位素内标法,样品经乙腈提取,采用混合型固相分散萃取剂净化,加入分析保护剂校正基质效应。色谱柱为DB-5MS(30 m×0.25 mm×0.25μm),程序升温,GC-MS-MS测定。124种农药残留在0.005~0.40μg/m L内呈线性关系,在0.06~0.3 mg/kg内的平均回收率为84.8%~108.7%,RSD为2.1%~12%,方法检出限(LOD)为0.005~0.013 mg/kg。该方法适合于中草药中农药多残留的同时检测。     

改良的QuEChERS-气相色谱-质谱联用法测定茶叶中多种农药残留

建立了以QuEChERS作为前处理方法,气相色谱/质谱联用法同时测定茶叶中33种农药残留的检测方法。样品经改进的QuEChERS法进行提取净化,采用DB-5MS(30m×0.25mm×0.25μm)毛细管色谱柱分离,选择离子模式下同时测定,外标法定量。33种农药残留在0.01~3.00mg/L范围内线性关系良好,相关系数均大于0.999。方法的检出限为4.0~35μg/kg,样品平均添加回收率为82.7%~103.8%,相对标准偏差为0.73%~6.8%。方法适用于茶叶中毒死蜱、联苯菊酯等33种不同类型农药残留的同时检测。     

固相萃取-气相色谱/质谱法测定水中6种有机磷酸酯类阻燃剂和增塑剂

采用C18固相萃取小柱富集环境水样中6种常见的有机磷酸酯类阻燃剂和增塑剂,经气相色谱/质谱(选择离子扫描模式)检测,内标法定量,优化了固相萃取和气相色谱质谱检测参数。磷酸三(丁氧乙基)酯二次回归相关系数大于0.999,定量限为32ng/L。其余磷酸三丁酯、磷酸三(2-氯乙基)酯、磷酸三(2-氯异丙基)酯、磷酸三(1,3-二氯异丙基)酯和磷酸三苯酯5种有机磷酸酯组分在10~800μg/L浓度范围线性相关系数大于0.999,定量限介于1.1~4.1ng/L。纯水加标样品中6种组分回收率范围为73%~112%,相对标准偏差范围为1.2%~12.9%。应用该方法分析了太湖、长江和自来水样品,均检出多种有机磷酸酯组分,且太湖中浓度水平高于长江。实际样品中6种组分的加标回收率范围为83%~146%,相对标准偏差范围为0.9%~15.1%。     

同位素内标稀释气相色谱-质谱联用法测定果蔬中的滴滴涕含量

建立了果蔬中滴滴涕(DDT)的气相色谱-质谱联用的测定方法。样品用乙腈提取,采用Florisil固相萃取柱净化,以HP-5ms色谱柱(30m×0.25mm×0.25μm)分离,在选择离子模式(SIM)下,以自行研制的p,p′-DDT-D8为内标进行定性定量分析。线性范围为1~1 000μg/L,检出限为0.02~0.05μg/kg,加标回收率为88.67%~101.73%,相对标准偏差(RSD)为1.6%~3.8%(n=5)。该方法为果蔬中滴滴涕的检测提供了一种可靠实用的方法。     

加速溶剂萃取和净化-气相色谱/三重四极杆串联质谱法测定水体沉积物中多氯联苯

建立了加速溶剂萃取同步净化-气相色谱/三重四极杆串联质谱法测定水体沉积物中7种指示性多氯联苯(PCB28,PCB52,PCB101,PCB118,PCB153,PCB138,PCB180)的方法。通过加速溶剂萃取条件和弗罗里硅土净化剂的优化,一步完成了萃取和净化过程,很好地去除了基质干扰。采用改进的色谱柱提高了分析效率,通过优化三重四极杆串联质谱的离子对(母离子/子离子)、碰撞电压、扫描峰宽等条件,显著提高了7种多氯联苯的灵敏度。7种多氯联苯在0.1~50μg/L浓度范围内线性良好,线性系数(R2)为0.9997~0.99993,方法检出限为0.005~0.010μg/kg。在2.0μg/kg和20.0μg/kg两个浓度添加水平,其回收率为83.5%~96.1%和85.1%~97.5%,相对标准偏差(RSD)为2.4%~7.6%和1.5%~8.2%。该方法已成功应用于实际水体沉积物中多氯联苯的测定。     

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.