气相色谱-串联质谱法测定鱼肉中毒死蜱及其代谢产物3,5,6,-三氯-2-羟基吡啶的残留量

采用气相色谱-串联质谱法(GC-MS/MS)测定鱼肉中毒死蜱及其代谢产物3,5,6,-三氯-2-羟基吡啶(TCP)残留量。样品经1mol·L-1盐酸-乙腈(1+99)混合液提取,提取液于-20℃冷冻去除脂肪,浓缩近干,残渣用乙酸乙酯溶解后与N-甲基-N-叔丁基二甲基硅基三氟乙酰胺进行衍生反应,产物经净化后采用GC-MS/MS测定。毒死蜱和TCP的线性范围分别为2.0~2 000,1.0~1 000μg·L。鱼肉中毒死蜱和TCP的检出限(3S/N)分别为0.5,0.3μg·kg-1,测定下限(10S/N)分别为1.7,1.0μg·kg-1。加标回收率分别为84.6%~95.6%,73.8%~82.7%,测定值的相对标准偏差(n=6)分别小于10%,13%。     

超高效液相色谱-串联质谱法分析鸡蛋中利巴韦林及其代谢物残留

建立了超高效液相色谱-串联质谱法同时快速测定鸡蛋中利巴韦林及其两种主要代谢物 TCONH2和RTCOOH 的分析检测方法。样品采用乙腈-水(9∶1, V/ V)提取,乙腈饱和正己烷除脂,C18结合 GCB 进行固相分散萃取除杂,Agilent ZORBAX SB-Aq 色谱柱(100 mm ×3.0 mm,1.8μm)分离,超高效液相色谱-串联质谱测定。结果表明：利巴韦林、TCONH2和 RTCOOH 分别在2.0~200μg/ L,0.5~200μg/ L,5.0~200μg/ L 浓度范围内,线性良好,相关系数 R2>0.99,检出限分别为0.54,0.09和1.54μg/ L,定量限分别为1.79,0.31和5.13μg/ L。在5.0,10.0和50.0μg/ L 加标水平下,利巴韦林和 RTCOOH 回收率分别为96.1%~99.6%和42.9%~58.3%;在0.5,2.0和5.0μg/ L 加标水平下,TCONH2的回收率为75.9%~106.7%,相对标准偏差均为4.2%~12.7%。实际样品测定结果表明,本方法操作简单、快速、准确,能够满足鸡蛋中利巴韦林及其两种主要代谢物的分析检测。     

超高效液相色谱-串联质谱法测定鸡血浆中利巴韦林及其主要代谢物

建立了同时检测血浆中利巴韦林(Ribavirin)及其主要代谢物1H-1,2,4-三氮-3-甲酰胺(TCONH2)和1-β-D-呋喃基核糖-三氮唑-3-羧酸(RTCOOH)的超高效液相色谱-串联质谱(UPLC-MS/MS)分析方法。鸡血浆样品加入13C5-利巴韦林内标,以甲醇沉淀蛋白,经ZORBAX SB-Aq(100 mm×3 mm,1.8μm)色谱柱分离,以0.1%甲酸水-甲醇为流动相,梯度洗脱,采用正离子多反应监测模式(MRM),内标法定量。结果表明:利巴韦林、TCONH2与RTCOOH的线性范围分别为5~5 000,5~5 000,50~5 000μg/L,相关系数(r2)分别为0.994 7,0.999 2,0.997 6。质控样品的加标回收率为84.1%~108.2%,批内相对标准偏差(RSD,n=6)为1.6%~13.4%,批间RSD(n=12)为3.8%~16.9%。样品的检出限(S/N=3)为2~10μg/L。本方法快速简便,有效排除了内源性干扰,方法的线性范围宽,重复性好,适用于血浆样品中利巴韦林及主要代谢产物的测定。     

亲水作用色谱-串联质谱测定尿液中尼古丁和可替宁

建立了测定人尿液中尼古丁和可替宁含量的亲水作用色谱-串联质谱(HILIC-MS/MS)方法。尿样加入尼古丁-d4和可替宁-d3同位素内标后,用水稀释10倍,经过滤后的滤液由超高效液相色谱-串联质谱(UPLC-MS/MS)进行分离分析。采用ACQUITY UPLC~BEH HILIC色谱柱(50 mm×3.0 mm,1.7μm),以甲醇和体积分数为0.1%的氨水为流动相,流速为0.2 mL/min,在电喷雾电离源正离子模式下测定尿液中尼古丁和可替宁的含量,用标准曲线法定量。尼古丁和可替宁在1.0~1 000μg/L范围内线性关系良好,相关系数分别为0.994 9和0.995 8;检出限分别为0.082μg/L和0.077μg/L;定量限分别为0.27μg/L和0.26μg/L;加标回收率分别为90.4%~103.5%和93.0%~104.6%;相对标准偏差分别为4.80%~6.21%和4.22%~7.15%。应用所建立的方法测定了200份尿样,结果表明,吸烟人群尿中尼古丁含量为26.68~854.30μg/L,可替宁含量为36.66~1 191.18μg/L(n=86,M_(nicotine)=76.00μg/L,M_(nicotine)=83.52μg/L,M为中位数);非吸烟人群尿中尼古丁含量为5.08~69.66μg/L,可替宁含量为3.16~28.21μg/L(n=114,Mnicotine=7.53μg/L,M_(nicotine)=3.79μg/L)。该方法快速灵敏,操作简单,适用于尿样中尼古丁和可替宁的批量测定,能满足烟草暴露评价的需要。     

顶空固相微萃取-气相色谱/质谱联用分析果汁中愈创木酚和2,6-二溴苯酚

建立了HS-SPME-GC-MS分析果汁中脂环酸芽孢杆菌产生的主要代谢产物的方法。采用顶空-固相微萃取捕集目标代谢产物,利用气相色谱-质谱联用对愈创木酚和2,6-二溴苯酚进行定性和定量分析。在优化后的萃取条件下,愈创木酚在0.49~2.0×10~3μg/L和2,6-二溴苯酚在0.42~1.7×10~3μg/L质量浓度范围内线性关系良好,相关系数(r)分别为0.9981和0.9976,回收率为82.1%~125%,相对标准偏差(n=6)为5.2%~6.0%。方法可用于果汁中脂环酸芽孢杆菌主要代谢产物的检测。     

黄嘌呤和鸟嘌呤在石墨烯-聚唑类化合物修饰电极上电化学行为

采用滴涂法和循环伏安法制备石墨烯-聚唑类化合物复合膜修饰玻碳电极,分别用循环伏安法和差分脉冲伏安法研究黄嘌呤和鸟嘌呤混合物在修饰电极上的电化学行为。在0.2 mol/L的磷酸盐缓冲液(p H 5.5)中,黄嘌呤和鸟嘌呤混合物在修饰的玻碳电极上具有较好的电化学行为。鸟嘌呤和黄嘌呤分别在4.0×10~(-4)~4.0×10~(-6)mol/L和4.0×10~(-5)~4.0×10~(-8)mol/L范围内有较好的电化学响应,鸟嘌呤和黄嘌呤检出限分别为4.0×10~(-7)mol/L和4.0×10~(-9)mol/L。方法用于同时测定人体尿液中鸟嘌呤和黄嘌呤,回收率分别为102.1%~105.9%和96.9%~106.5%。     

同位素稀释结合固相萃取快速测定动物组织中β2-兴奋剂

本文采用同位素稀释结合固相萃取技术,测定动物组织中特布他林、克伦特罗、沙丁胺醇、莱克多巴胺4种β2-兴奋剂。动物组织加同位素内标D3-沙丁胺醇和D9-克伦特罗,经甲醇提取后,正己烷脱脂,过SLS离子交换固相萃取柱净化,用BSTFA 1%(φ)TMCS衍生,采用GC/MS进行测定,内标法定量。实验表明,动物组织中添加2.0~10.0μg/kg浓度水平的β2-兴奋剂,方法回收率在72.5%~97.9%,相对标准偏差1.0%~11.4%,线性范围为12.5~500μg/L,样品中特布他林、克伦特罗、沙丁胺醇、莱克多巴胺最低检出限分别为0.5μg/kg、1.0μg/kg、0.5μg/kg和1.0μg/kg。     

火焰原子吸收光谱法测定铼产品中的痕量钠

建立了火焰原子吸收光谱法测定高铼酸、高铼酸铵、铼粉中痕量钠的方法,对样品的预处理和测定钠的条件进行了研究。结果表明:水溶解法、硝酸溶解法或硝酸-硫酸溶解法溶解样品完全,测得钠的结果吻合;于选定条件下,钠的测定浓度在0.020 0~0.500 0μg/mL范围内线性良好;测定高铼酸、高铼酸铵和铼粉样品中0.27~0.47mg/L、0.000047%~0.00048%和0.000040%~0.00049%的钠含量,检出限、相对标准偏差(RSD,n=7)、加标回收率分别为高铼酸3×10-4μg/mL、6%~10%、98%~102%,高铼酸铵3×10-4μg/mL、8%~9%、96%~102%和铼粉3×10-4μg/mL、5%~9%、96%~103%。方法结果准确、分析快速、操作简便,应用于实际的样品分析,结果满意。     

超高效液相色谱-串联质谱法快速测定化妆品中水杨酸

提出了超高效液相色谱-串联质谱法测定化妆品中水杨酸含量的方法。化妆品试样用甲醇溶解,振荡提取20 min,离心分离取上清液过ACQUITYTMBET C18色谱柱(2.1 mm×100 mm,1.7μm)并用乙腈和甲酸-水(0.3+99.7)溶液(体积比6比4)的混合溶液作为流动相进行分离,串联质谱法进行测定。采用正离子模式多反应监测,同位素内标法定量。水杨酸的线性范围为1.0~5.0×103μg.L-1,方法的检出限(3S/N)为0.15μg.L-1,测定下限(10S/N)为0.50μg.L-1。方法用于分析8种化妆品试样,回收率在97.3%~107.0%之间,相对标准偏差(n=5)在2.0%~3.8%之间。     

高效液相色谱-电感耦合等离子体质谱法测定化妆品中2-溴-2-硝基-1,3-丙二醇

建立了高效液相色谱-电感耦合等离子体质谱(HPLC-ICP-MS)测定化妆品中2-溴-2-硝基-1,3-丙二醇的方法。采用ZORBAX RX-C_8色谱柱(150×2.1 mm,5μm)进行分离,以甲醇-水-5%磷酸(10∶985∶5,用2 mol/L NaOH调至pH 3.0)为流动相,流速为0.7 m L/min,柱温为室温。结果显示,2-溴-2-硝基-1,3-丙二醇在2.5 min处出峰,其线性范围为0.01~1.0 mg/L,相关系数为0.999 9。不同基质化妆品的方法检出限均为1.0μg/g,回收率为94.6%~101.3%,相对标准偏差(RSD,n=6)为1.5%~4.5%。该方法快速、准确、灵敏、无干扰,适用于化妆品中2-溴-2-硝基-1,3-丙二醇的定性定量测定。     

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.