顶空-气相色谱法同时测定食品包装复合膜中13种有机溶剂残留

提出了食品包装复合膜中残留的13种有机溶剂(苯类、醇类、酮类、酯类等)的顶空-气相色谱法。分别选择100℃及30 min作为样品在顶空瓶中的平衡温度和平衡时间。选用CP-WAX毛细管色谱柱(50 m×0.25 mm,0.2μm)分离,氢火焰离子检测器测定。13种有机溶剂在25 min内能完全分离。13种有机溶剂的质量浓度在0.086~1.72 mg.m-2范围内呈线性,测定下限(10S/N)在0.003~0.007 mg.m-2之间。方法用于复合膜样品分析,加标回收率在90.5%~98.7%之间,相对标准偏差(n=6)在1.85%~4.86%之间。     

顶空/气相色谱-质谱法测定圆珠笔中8种挥发性苯系物

建立了顶空/气相色谱-质谱法测定圆珠笔中8种挥发性苯系物(苯、甲苯、乙苯、对二甲苯、间二甲苯、异丙苯、邻二甲苯和苯乙烯)含量的分析方法。选择顶空平衡温度和时间分别为70℃和40 min,以HP-INNOWax色谱柱(60 m×320μm×0.25μm)分离,采用选择离子监测模式(SIM)检测,外标法定量。结果显示,8种苯系物在0.005～0.5 mg/L质量浓度范围内均与对应的峰面积呈良好的线性关系(r~20.999),检出限(S/N=3)为0.01～0.02 mg/kg,加标回收率为86.0%～104%,相对标准偏差(RSD)为2.3%～9.6%。该方法操作简单,快速,且灵敏度高,适用于圆珠笔中挥发性苯系物的快速检测。     

高效液相色谱-四极杆/线性离子阱质谱仪测定盐酸决奈达隆中两种基因毒性杂质的痕量残留

建立了高效液相色谱-四极杆/线性离子阱质谱仪(HPLC-QTRAP-MS/MS)测定盐酸决奈达隆药物中两种基因毒性杂质(杂质C和D)痕量残留的分析方法。盐酸决奈达隆药物以0.1%甲酸水溶液-乙腈(20∶80)溶解后,分别采用Agilent Extend-C18色谱柱(1.8μm,2.1 mm×50 mm)或YMC Pack-CN色谱柱(5μm,4.6 mm×250 mm)进行分离,以0.1%甲酸水和乙腈作为流动相分别进行梯度洗脱,电喷雾正离子(ESI+)扫描方式下选择离子监测(SRM)模式对样品进行检测。结果表明,杂质C和D在1.0~50μg/L范围内线性关系良好,检出限(S/N=3)分别为0.20μg/L和0.30μg/L,定量下限(S/N=10)分别为0.80μg/L和1.0μg/L。该方法操作简单、灵敏度高、重现性好,可用于盐酸决奈达隆药物中两种基因毒性杂质痕量残留的测定。     

顶空/气相色谱-质谱法同时测定蔬菜和水中5种挥发性农药助剂残留

建立了同时测定蔬菜和水样品中甲醇、甲苯、邻二甲苯、间二甲苯、对二甲苯等5种挥发性农药助剂残留量的顶空/气相色谱—质谱分析方法(HS/GCM S)。对溶剂种类、Na Cl溶液浓度、平衡温度、平衡时间以及GC-M S等分离检测条件进行优化。当顶空平衡温度为80℃,平衡时间为20 min,采用DB-624毛细管柱(30 m×0.25 mm×1.4μm)进行分离,选择离子监测模式(SIM)进行检测,可获得良好的分离效果和定量结果。甲醇和苯系物分别在0.12~80 mg/L,0.0003~0.20 mg/L的浓度范围内线性关系良好,相关系数均不小于0.9993,检出限分别为0.04 mg/kg和0.0001 mg/kg。5种挥发性农药助剂在不同添加水平下的平均回收率为63.5%~115.4%,相对标准偏差为1.2%~9.4%。方法适用于西红柿、黄瓜等蔬菜和水中挥发性有机溶剂类农药助剂的残留检测。     

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。     

液液萃取-气相色谱/质谱法同时测定水中3种季胺盐化合物

建立了液液萃取-气相色谱/质谱同时测定水中3种典型季胺盐化合物十二烷基三甲基氯化铵(DTAC)、十六烷基三甲基溴化铵(CTAB)、双十二烷基二甲基氯化铵(DDAC)的分析方法。采用电子轰击(EI)-选择离子模式(SIM)进行定性与定量分析,DTAC和CTAB的特征离子为m/z 58,DDAC的特征离子为m/z 212。考察了萃取剂种类、萃取次数、pH值以及盐度对萃取效率的影响。以HCl及30%NaCl溶液调节水样pH值为1.5及盐度为3%,以5 mL三氯甲烷萃取2次,3种目标化合物的线性范围在0.01~2.0 mg/L之间,检出限LOD(S/N=3)为2.5~8.5μg/L。以此方法测定自来水、湖水、河水、选矿废水样品,3种目标化合物的含量在0.06~2.45 mg/L之间,不同加标水平(0.2,0.5和1.0 mg/L)回收率在65%~113%之间,相对标准偏差在3.8%~23.0%之间。     

高效液相色谱-四极杆/线性离子阱质谱测定替米沙坦中N-甲基邻苯二胺残留量

建立了高效液相色谱-四极杆/线性离子阱质谱(HPLC-QTRAP-MS/MS)测定替米沙坦中N-甲基邻苯二胺残留量的分析方法。替米沙坦药物以水-乙腈(80∶20,体积比)溶解后,采用Agilent Eclipse XDB-C18色谱柱(3.5μm,2.1 mm×100 mm)进行分离,以0.1%(体积分数)甲酸水和乙腈作为流动相进行梯度洗脱,电喷雾正离子(ESI+)扫描方式下选择离子监测(SRM)模式对样品进行检测。结果表明,N-甲基邻苯二胺在2.0~50μg/L范围内线性关系良好(r0.99),检出限(S/N=3)为0.5μg/L,定量下限(S/N=10)为2.0μg/L。该方法操作简单、灵敏度高、重现性好,可用于替米沙坦中N-甲基邻苯二胺残留量的测定。     

液液萃取/高效液相色谱法测定豆干与腐竹中溶剂黄2及溶剂黄56

建立了液液萃取/高效液相色谱法测定豆干和腐竹中溶剂黄2和溶剂黄56的分析方法。样品经乙腈饱和的正己烷提取后,加入正己烷饱和的乙腈萃取,将乙腈层转入浓缩瓶内,重复萃取3次,将萃取液浓缩后用乙腈定容。采用Agilent TC-C18(4.6 mm×250 mm,5μm)色谱柱对样品进行分离;柱温为30℃;流动相为水-甲醇(20∶80);流速为1.0 m L/min;检测波长为410 nm。溶剂黄2和溶剂黄56在0.30~50 mg/L浓度范围内线性关系良好,其检出限(LOD)和定量下限(LOQ)分别均为0.15 mg/kg和0.50 mg/kg,方法的平均回收率为85.4%~94.6%,相对标准偏差(RSD,n=6)为0.3%~2.3%。该方法重复性好,灵敏度高,适用于豆干和腐竹中溶剂黄2和溶剂黄56含量的测定。     

禽蛋中头孢噻肟残留的高效液相色谱-串联质谱法测定

建立了高效液相色谱-串联质谱(LC-MS/MS)测定禽蛋中头孢噻肟药物残留的方法。禽蛋样品中的头孢噻肟用纯水提取,乙腈沉淀蛋白,Oasis HLB(500 mg,6 mL)固相萃取柱净化,8 mL甲醇洗脱。采用Zorbax XDB-C18(2.1 mm×50 mm,3.5μm)色谱柱,以0.2%甲酸水-乙腈为流动相,0.3 mL/min梯度洗脱,经高效液相色谱分离后,采用电喷雾质谱正离子模式电离,多反应选择离子检测(MRM)模式测定。检测离子对为m/z456.1/396.1、m/z456.1/324.1,其中m/z456.1/396.1为定量离子对。在1.35~135μg/L范围内标准曲线的线性关系良好,相关系数为0.999 3;在1.0、50.0、100μg/kg3个添加水平的平均加标回收率为87%~99%,相对标准偏差为1.9%~3.9%;方法检出限为0.3μg/kg,定量下限为1.0μg/kg。该方法简便、灵敏、准确、可靠,适用于禽蛋中头孢噻肟药物残留的分析。     

顶空-气相色谱法测定海水中8种苯系物

提出了顶空-气相色谱法测定海水中残留的8种苯系物的方法。分别选择40℃及30min作为样品在顶空瓶中的平衡温度和平衡时间。选用Nukol毛细管色谱柱(30m×0.25mm,0.25μm)分离,氢火焰离子化检测器测定。8种苯系物在13min内能完全分离。8种苯系物的质量浓度在10.0～200μg.L-1范围内与其峰面积呈线性关系,检出限(3S/N)均为2μg.L-1。以海水样品为基体,在3个浓度水平上进行加标回收试验,回收率在93%～119%之间,相对标准偏差(n=6)在1.1%～5.3%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%.     

α-Amino acid derived enaminones and their application in the synthesis of N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates and other heterocycles

A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives.     

Specific intramolecular aromatic CH insertion of diazosulfonamides

The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp³)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp²)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp²)?H and aliphatic 1,5- and 1,6-C(sp³)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp³)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp²)?H insertion.     

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.     

N-Heterocyclic carbene-palladacyclic complexes: synthesis,characterization and their applications in the C-N coupling and α-arylation of ketones using aryl chlorides

N-Heterocyclic carbene-palladacyclic complexes 3 were successfully achieved in a one-pot procedure under mild conditions. The structure of 3a was unambiguously confirmed by X-ray single crystal diffraction and it was an active catalyst in the Buchwald-Hartwig amination and α-arylation of ketones even at very low catalyst loadings (0.01?mol%).     

Iodine-mediated oxidative Pictet-Spengler reaction using terminal alkyne as the 2-oxoaldehyde surrogate for the synthesis of 1-aroyl-β-carbolines and fused-nitrogen heterocycles

An efficient iodine-mediated oxidative Pictet-Spengler reaction in dimethyl sulphoxide (DMSO) using terminal alkynes as the 2-oxoaldehyde surrogate for the synthesis of aryl (9H-pyrido[3,4-b]indol-1-yl)methanones is described. The scope of the protocol includes the total synthesis of Fascaplysin, Eudistomins Y₁ and Y₂. The methodology is extended for preparing pyrrolo[1,2-a]-quinoxaline and indolo[1,5-a]quinoxaline derivatives. The utility of 1-aroyl-β-carbolines was demonstrated by performing palladium-catalyzed β-carboline directed ortho-C(sp2)-H functionalization of the phenyl ring with thiomethyl (SMe) group using DMSO as source and for accessing 4-aryl-canthin-6-ones.     

Facile synthesis of bicyclic 1-arylpyrazol-5-ones

In this Letter, we described a facile method for constructing fused bicyclic 1-arylpyrazol-5-one ring system. We employed various methylene-containing carboxylic acids as the substrates and proved that the pyrazolone ring closure requires activated methylene group in intermediate II. Accordingly, a series of structurally diversified, fused bicyclic 1-arylpyrazol-5-ones was prepared in moderate to high yields using the requisite substrates.     

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.     

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.     

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.