气相色谱-质谱法测定禽肉中二氯二甲吡啶酚残留量

球虫病是禽类致病性较强的1种寄生虫病,危害性极大.二氯二甲吡啶酚是疗效较高的1种抗球虫剂,其英文名为clopidol.随着科学技术和国际贸易的发展,世界各国对食品安全卫生项目的要求越来越高,因此二氯二甲吡啶酚作为一种兽药,不少国家都有检测的要求.禽肉中二氯二甲吡啶酚残含量测定,主要采用气相色谱法或液相色谱法.但上述方法测定时,一旦有相同保留时间的干扰物,就很容易造成假阳性.本文应用气相色谱-质谱法(GC-MS)测定禽肉中二氯二甲吡啶酚残含量,能对可疑阳性样品进行准确的鉴别和定量测定,为控制兽药残留检测提供了新的分析方法.     

用量热滴定法研究2，4－二氯酚与吡啶的氢键络合反应

用量热滴定法研究２，４－二氯酚与吡啶的氢键络合反应李志伟，陈爱通，胡日恒（天津大学化学系，天津，３０００７２）（中国科学院化学研究所）关键词２，４－二氯酚，吡啶，正庚烷，氢键，量热滴定利用反应热测定样品滴定度是一种新兴的方法。在反应常数为１０３～１０...     

高效液相色谱-电化学阵列检测器检测10种磺胺药物在鸡肉中的残留

建立了一步有机溶剂提取、HPLC分离、多孔石墨电极阵列检测器检测10种磺胺类药物在鸡肉中残留量的方法。采用乙腈-氯仿混合液(乙腈：氯仿=10：1)提取，10种磺胺药物的提取收率均大于50％；研究了磺胺类药物在多孔石墨电极上的氧化还原特征，确定检测电势为455，560，630，670和710mV；优化了HPLC分离条件，Hypersil BDS C-18色谱柱，pH5、30mmoL／L磷酸二氢钠、8．5％-37．5％乙腈(V/V)线性梯度洗脱，40min内实现10种磺胺药物的基线分离，鸡肉中提取的杂质不干扰样品分离；方法的检出限(S/N=3)为磺胺二甲异喔唑(SIA)40μg／kg及磺胺(SA)、磺胺嘧啶(SDZ)、磺胺甲基嘧啶(SMR)、磺胺二甲基嘧啶(SMZ)、磺胺吡啶(SPD)、磺胺噻唑(STZ)、磺胺甲噻二唑(SMTZ)、磺胺氯哒嗪(SCP)和磺胺甲基异喔唑(SMX)等分别为20μg／kg，在0．1—2．0mg/L浓度范围内各磺胺类药物与其响应信号呈现良好的线性关系，相关系数(r)均大于0．9978；电极再生方法简单，可实现在线清洗，适用于食用畜禽产品中磺胺类药物残留量的分析。     

超高效液相色谱-串联质谱法同时测定鸡肉中的二氯二甲吡啶酚、磺胺类和喹诺酮类药物残留

采用超高效液相色谱-串联质谱（UPLC-MS/MS）在正离子模式下通过多反应监测（MRM）方式同时测定了鸡肉组织中二氯二甲吡啶酚、磺胺嘧啶、磺胺二甲基嘧啶、磺胺对甲氧嘧啶、磺胺甲氧哒嗪、诺氟沙星、氧氟沙星、环丙沙星、恩诺沙星等9种药物残留。试样经乙腈均质提取,冷冻离心脱脂,旋转蒸发浓缩,用流动相复溶后经乙腈饱和的正己烷除油,随后进行UPLC-MS/MS定性定量分析。该方法测定9种药物的检出限为0.1 μg/kg,定量限为0.5 μg/kg。在添加水平分别为0.5、1.0和2.0 μg/kg时,9种药物的加标回收率为81.5%~97.6%,相对标准偏差（RSD）为2.1%~8.9%。该方法简便、准确,可作为鸡肉中9种药物残留检测的确证方法。     

高效液相色谱法测定鸡组织中克球酚残留量

克球酚(3,5-二氯-2,6-二甲基-4-吡啶酚)是一种防治家禽球虫病的饲料添加剂。世界各国对其在鸡组织中的残留限量均有严格规定。关于它的残留量的分析有重氮甲烷、丙酸酐衍生化气相色谱法和不进行衍生化而直接测定的液相色谱法。后者提取净化效果欠佳,测定低含量时基线不稳定,有杂峰干扰定量。本文改进了样品提取方法,提高了     

聚苯乙烯固载聚乙二醇和邻苯二甲酰亚胺的N—烃基化反应中的…

本文报道了聚苯乙烯固载聚乙二醇作为相转移催化剂催化合成Ｎ－烃基邻苯二甲酰亚胺。在无水碳酸钾、无水氟化钾、乙腈和聚苯乙烯固载聚乙二醇４００或聚苯乙烯固载吡啶翁盐－聚乙二醇４００等作用下，合成了三种Ｎ－烃基邻苯二甲酰亚胺。     

聚苯乙烯固载聚乙二醇在邻苯二甲酰亚胺的N-烃基化反应中的相转移催化作用

本文报道了聚苯乙烯固载聚乙二醇作为相转移催化剂催化合成Ｎ－烃基邻苯二甲酰亚胺。在无水碳酸钾、无水氟化钾、乙腈和聚苯乙烯固载聚乙二醇４００或聚苯乙烯固载吡啶盐一聚乙二醇４００等作用下，合成了三种Ｎ－烃基邻苯二甲酰亚胺。     

气相色谱-串联质谱法快速测定鸡肉组织中氯羟吡啶残留量

采用气相色谱-串联质谱法快速测定鸡肉组织中的氯羟吡啶残留,样品经乙腈-水提取,冷冻脱脂后,直接以丙酸酐衍生,采用气相色谱-串联质谱(GC-MS/MS)进行分析,多反应监测(MRM)模式检测。结果表明,氯羟吡啶在0.5~40 ng/m L浓度范围内呈良好的线性关系,方法的定量下限为5.0μg/kg,回收率为101.5%~111.8%,相对标准偏差(RSD)小于7.7%。该方法简便、快速、灵敏度高,重现性好,可用于鸡肉组织中氯羟吡啶的快速确证检测。     

固相萃取高效液相色谱法测定动物肝中四种磺胺残留量

用高效液相色谱法同时测定了动脉肝中四种磺胺药物残留量。样品经乙腈－氯仿提取，液－液萃取、固相萃取小柱净化后用HPLC分离，外标法定量。方法简便、快速，下限为0.050mg/kg，回收率＞82％，相对标准偏差＜5％。     

2-(3,5-二氯-2-吡啶偶氮)-5-二甲氨基苯胺激光热透镜光谱法测定钯

基于2－（3，5－二氯－2－吡啶偶氮）－5－二甲氨基苯胺（3，5-diCl-PADMA)与钯的显色反应，以激光热透镜头谱法测定了微量钯。实验表明，在强酸性介质中，Pd^2 与3，5－diCL-PADMA室温显色形成稳定的蓝色配合物，最大吸收波长位于623nm处，与所用激光器输出激光波长匹配较好，从而建立了激光热透镜光谱法测定钯的新方法。钯浓度分别在0．005－0．04mg/L和0．03－0．025mg/L范围内呈线性关系，方法灵敏度高，选择性、重现性好，用于样品测定，结果满意。     

A carbanion induced synthesis of highly congested pyrazole and imidazole containing heterocycles

An efficient approach to the synthesis of highly congested di, penta and hexacyclic pyrazoles as well as imidazole fragment containing novel heterocyclic molecule has been developed through a carbanion induced transformation of suitably functionalized 2H-pyran-2-ones, benzo[h]chromene and thiochromeno[4,3-b]pyrans. Due to the presence of fluorescence, we report their prime application metal sensor as off/on switching in ferric ions.     

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.     

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%).     

Selective synthesis of 4,5-dihydroimidazo- and imidazo[1,5-a]quinoxalines via modified Pictet–Spengler reaction

An efficient tandem approach for the selective synthesis of 4,5-dihydroimidazo[1,5-a]quinoxalines 6a–g and imidazo[1,5-a]quinoxalines 7a–h by the reaction of 2-imidazolyl anilines 4a–c with aryl aldehydes 5a–k under mild reaction conditions is described. Introduction of electron releasing alkyl groups in substrates 4a–b was found to be instrumental for the success of the reaction.     

Understanding the Diels-Alder reactivity of 1,2-azaborine analogues

The Diels-Alder reactivity of 1,2-heteroborines (H₄C₄B(H)X, X?=?NH, PH, AsH; O, S, Se) has been computationally explored by means of Density Functional Theory (DFT) calculations. The influence of the HB?=?X fragment on the reactivity of the system has been quantitatively analyzed in detail by means of the so-called Activation Strain Model (ASM) of reactivity. It is found that the interaction between these species and the dienophile is significantly stronger than that computed for their all-carbon isoelectronic counterpart, benzene. In addition, the strain energy plays a key role in the observed reactivity trends. The role of the aromaticity strength of these heteroarenes on the reactivity is also assessed.     

Synthesis of N-substituted carbazolones from α-iodo enaminones via Pd(0)-catalyzed intramolecular coupling under microwave irradiation

A variety of N-aryl and N-alkyl carbazolones were conveniently achieved in good to high yields via Pd₂(dba)₃-mediated intramolecular coupling of N-substituted α-iodo enaminones under microwave irradiation. The Pd(0)-catalyzed cyclization was found to proceed favorably with the more electron-deficient phenyl ring during the reactions involving unsymmetrical N,N-diaryl α-iodo enaminones. This unique property enables the construction of carbazolone skeleton containing nitro substituted benzenoid ring.     

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.     

Synthesis of substituted 2,4,5,6-tetrahydrocyclopenta[c]pyrazoles and 2,4,5,6-tetrahydropyrrolo[3,4-c]pyrazoles by intramolecular nitrilimine cycloaddition

Both substituted 2,4,5,6-tetrahydrocyclopenta[c]pyrazoles and 2,4,5,6-tetrahydropyrrolo[3,4-c]pyrazoles have been synthesized by the 3+2 intramolecular dipolar cycloaddition of nitrilimines to alkynes. This cyclization has been extended to more versatile 3-bromo derivatives by the use of alkynylbromides as dipolarophiles.