全二维气相色谱-电子捕获检测器法分析土壤中毒杀芬同类物的残留

建立了全二维气相色谱-电子捕获检测器(GC× GC-μECD)检测土壤中毒杀芬同类物的分析方法.以非极性的DB- XLB(20 m×0.25 mm×0.25 μm)为第一色谱柱,中等极性的BPX-50(2 m×0.1 mm×0.1 μm)为第二色谱柱,对土壤中23种高关注毒杀芬同类物进行了分离鉴定,并采用基质曲线外标法进行定量分析.本方法在1～200,μg/L浓度范围内,毒杀芬同类物的线性相关系数(r2)均大于0.99,方法检出限(S/N=3)为0.039～0.482 μg/L,基质加标毒杀芬同类物的回收率为55％～115％,相对标准偏差(RSD)均小于30％(n=5).利用本方法对毒杀芬污染的土壤样品进行了测定,获得了较好的分离效果.     

毛细管气相色谱法测定作业场所空气中的1,3-丁二烯

依据GBZ/T 160.39–2007方法测定作业场所空气中的1,3-丁二烯时,采用毛细管色谱柱分离样品,对HP–1,HP–FFAP,DB–1701 3种极性不同的毛细色谱柱进行了对比,确定采用HP–1柱。1,3-丁二烯的质量浓度在45~450μg/m L范围内与色谱峰面积呈良好的线性关系,相关系数大于0.999,检出限为0.05μg/m L。解吸效率为87.9%~91.3%,方法精密度在1.5%~2.4%(n=6)之间。毛细管气相色谱法分离效果好,灵敏度高,方法检出限、精密度和解吸效率满足GBZ/T 160.39–2007的要求。     

正相高效液相色谱法快速测定化妆品中维生素K1

建立了快速测定化妆品中维生素K1的正相高效液相色谱方法。不同基质的样品由正己烷采用不同的方式进行提取,高速离心,过滤,以Si柱(4.6×250 mm,5μm)为分离色谱柱,体积比4:6的二氯甲烷-正己烷为流动相,等度洗脱,用高效液相色谱/二极管阵列检测器(λ=271 nm)进行定性、定量分析。对不同的色谱分离、提取和净化方法作了系统的研究,在优化实验条件下,维生素K1正反异构体与基体杂质分离效果良好,在0.5~50.0 mg/L范围内线性关系良好,相关系数R2为0.9998,方法的回收率为90.2%~96.8%,相对标准偏差小于8.6%,方法定量限为5.0 mg/kg。该方法可用于各类化妆品中维生素K1含量的检测。     

高效液相色谱法同时测定洗涤产品中7种防腐剂

建立同时测定洗涤产品中4-氯-3-甲酚、双氯酚、苄氯酚、邻苯基苯酚、对氯间二甲苯酚、三氯生、三氯卡班7种防腐剂的高效液相色谱分析方法。不同基质的样品经甲醇涡旋混匀及超声提取后,用X–Bridge C18反相色谱柱(250mm×4.6 mm,5μm)进行分离,以甲醇–水为流动相,梯度洗脱,采用二极管阵列检测器(DAD)进行检测,检测波长为285 nm。在优化的实验条件下,7种防腐剂的质量浓度在0.2~500 mg/L范围内与其色谱峰面积呈良好的线性关系,相关系数(r2)均为0.999 9,方法的检出限(S/N=3)为1.0~2.5 mg/kg,定量限(S/N=10)为3.0~7.5 mg/kg。7.5,25.0,75.0 mg/kg 3水平加标回收率为92.1%~105.8%,相对标准偏差为0.8%~4.5%(n=6)。该方法简单、快速、准确,适用于洗涤产品中7种防腐剂的测定。     

高效液相色谱-串联质谱法测定烟用香精香料中的甲基异噻唑啉酮及其氯代物的含量

采用高效液相色谱-串联质谱法测定烟用香精香料中的甲基异噻唑啉酮及其氯代物的含量。样品采用甲醇提取,以Agilent ZORBAX 300SB-C8色谱柱为分离柱,以不同体积比的甲醇和水混合液为流动相进行梯度洗脱,采用电喷雾正离子源多反应监测模式检测。甲基异噻唑啉酮及其氯代物的线性范围均为0.05~5.0mg·L~(-1),检出限分别为3.2,3.6μg·L~(-1)。加标回收率在77.1%~95.0%之间,测定值的相对标准偏差(n=6)均不大于5.0%。     

大体积进样离子色谱法测定环境水样中高氯酸根

采用大体积500μL进样离子色谱法,电导检测测定了几种水体中高氯酸盐的含量。分析柱为容量高、亲水性强的以脂肪族碳骨架为基质的阴离子交换柱IonPac AS20,淋洗液在线发生器自动产生35 mmol/LKOH淋洗液,0.25 mL/m in等浓度淋洗。这种新型的以脂肪族碳骨架为基质的阴离子交换柱的采用,极大的削弱了该色谱柱对对氯苯磺酸的保留,完全消除了现行美国EPA高氯酸盐分析方法中高氯酸根与对氯苯磺酸共淋洗的问题。方法对高氯酸根的检出限(S/N=3)为0.5μg/L,高氯酸根浓度在1~1000μg/L范围内具有良好的线性(r=0.9991)。将本方法应用于自来水、河水和雪水样品中高氯酸盐的检测,实际样品的加标回收率在87%~114%之间;1μg/L高氯酸根连续进样9次,色谱峰面积相对标准偏差(RSD)为6.9%。     

动物肌肉组织中己烯雌酚残留量的液相色谱-串联质谱法测定

建立了动物肌肉组织中己烯雌酚残留的液相色谱-串联质谱分析方法。样品用乙腈-甲酸溶液均质提取,以乙腈-水(体积比85∶15)为流动相经反相色谱柱分离后,采用多反应监测(MRM)负离子模式检测,定性离子对为m/z266.9/237.0和266.9/251.0;其中m/z266.9/251.0用于外标法定量。空白样品及其加标实验结果表明,特征离子相对强度比值稳定,无基质干扰,结合保留时间可实现准确的定性定量,方法检出限为0.10μg/kg(S/N=3),不同肌肉基质样本添加水平在0.5~5.0μg/kg时,平均回收率为82%~96%,相对标准偏差(n=6)为3.7%~6.4%。     

高效液相色谱法快速检测茶叶中三氯杀螨醇

建立了茶叶中三氯杀螨醇残留量的高效液相色谱快速检测方法。选择丙酮:正己烷(1:2,V/V)对不同茶叶中三氯杀螨醇农药残留进行提取,经浓硫酸净化,1 mL甲醇定容后供高效液相色谱检测。Agilent Acclaim TM 120 C_(18)色谱柱(250×4.6,5μm)分离,流动相为乙腈-水(85:15,V/V)混合溶剂,梯度洗脱。对不同茶叶类型,提取、净化条件进行考察优化。结果表明,标准工作曲线,在0.02~5 mg/kg范围内,三氯杀螨醇线性关系良好(r为0.9999),方法定量限为0.05 mg/kg。在绿茶、红茶、黄茶、青茶、白茶、黑茶6种茶叶中4个添加水平0.05,0.1,5,50 mg/kg的平均回收率范围分别为91.8%~108.3%,88.8%~102.5%,83.7%~94.3%,80.9%~84.2%,相对标准偏差在1.2%~14%之间(n=6)。     

固相萃取–气相色谱–负化学源质谱法检测水果和蔬菜中的毒杀芬

采用改进的分散固相萃取(QuEchERs)法对样品进行前处理,建立水果和蔬菜中毒杀芬残留的气相色谱–负化学电离源质谱(GC–NCI–MS)检测方法。样品中的毒杀芬由正己烷提取,经吸附剂PSA+GCB净化,在GC–NCI–MS的选择离子扫描模式下进样分析。毒杀芬的色谱保留时间在12.5~18.0 min区间内,采用面积归一化法积分,外标法定量。毒杀芬质量浓度在0.050~2.000 mg/L范围内与色谱峰面积呈良好的线性关系,相关系数r=0.999 1。分别以蓝莓、黄桃、菠菜为基质,在0.025,0.050 mg/kg添加水平下,毒杀芬的回收率为107.2%~118.1%,测定结果的相对标准偏差为5.5%~8.8%(n=6),定量限为0.025 mg/kg。该方法检测快速,适用于水果和蔬菜中毒杀芬残留的日常检测。     

高效液相色谱-串联质谱法快速测定水果中氯吡脲残留量

应用高效液相色谱-串联质谱法快速测定水果中的氯吡脲残留量。水果样品经乙腈均质提取,以N-丙基乙二胺、C18和无水硫酸镁作吸附剂净化。所得净化液以C18色谱柱为分离柱,以不同体积比混合的甲醇和5mmol·L-1乙酸铵溶液为流动相梯度洗脱进行分离,采用电喷雾正离子源多反应监测模式检测。氯吡脲的质量浓度在0.005~0.200mg·L-1范围内与峰面积呈线性关系,测定下限(10S/N)为1.0μg·kg-1。在0.01,0.05,0.10mg·L-1 3个浓度水平进行加标回收试验,回收率在86.4%~106%之间,相对标准偏差(n=6)在3.2%~9.5%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%.     

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.