牛奶中16种喹诺酮类药物残留量的高效液相色谱-串联质谱法测定

建立了牛奶样品中萘啶酸、噁喹酸、氟甲喹、诺氟沙星、依诺沙星、环丙沙星、洛美沙星、丹诺沙星、恩诺沙星、氧氟沙星、沙拉沙星、二氟沙星、麻保沙星、培氟沙星、司帕沙星、奥比沙星16种喹诺酮类兽药多残留量的液质联用确证方法.用酸性乙腈萃取样品中16种喹诺酮类药物残留,然后用正己烷脱脂,旋转蒸发仪浓缩,以Inertsil C8-3色谱柱为分离柱,在正离子模式下以电喷雾电离串联质谱仪进行测定.在10、50、100 μg/kg 3个浓度水平进行验证实验,方法的线性范围为10～100 μg/kg,平均回收率为69%～104%.相对标准偏差为4.1%～12.7%.     

蜂蜜中14种喹诺酮类药物残留的高效液相色谱-串联质谱测定

建立了同时测定蜂蜜中14种喹诺酮类药物残留的高效液相色谱-串联质谱分析方法.蜂蜜中喹诺酮类药物残留用0.05 mol/L磷酸盐缓冲溶液(pH＝3.0)提取,样液过滤后,经Oasis HLB固相萃取柱净化,氢氧化铵-甲醇溶液(体积比1:19)洗脱,蒸干定容后,用反相液相色谱分离,电喷雾正离子模式离子化,用多反应监测方式(MRM)监测,三重四极杆质谱测定.环丙沙星在0.4～100.0μg/kg,噁喹酸在0.4 ～50.0μg/kg,恩诺沙星、沙拉沙星、双氟沙星、依诺沙星、诺氟沙星在1.0～100.0μg/kg,氧氟沙星、单诺沙星、氟罗沙星、奥比沙星、麻保沙星在1.0～50.0μg/kg,司帕沙星、氟甲喹在2.0 ～100.0μg/kg范围内呈线性关系,相关系数r>0.997,在2.0、5.0、10.0、50.0 μg/kg 4个添加水平,回收率为66% ～111%,相对标准偏差(RSD)为1.3% ～13.6%.该方法操作简便,稳定性好,选择性好,灵敏度高,其检出限达1.0μg/kg.     

反相离子对液相色谱法同时测定11种氟喹诺酮类药物的研究

建立了高效液相色谱-荧光法同时测定11种氟喹诺酮类药物的分析方法.主要研究了流动相、流动相配比及流动相的pH对氟喹诺酮分离的影响.确定了液相色谱分析最佳条件.分离条件为:Xbridge Shield RP C18柱,以V(0.10%三氟乙酸)∶V(乙腈)∶V(甲醇)=89∶4∶7为流动相;检测波长为λex=280 nm和λem＝450 nm.方法检出限为:诺氟沙星、环丙沙星、培氟沙星和恩诺沙星0.007μg/mL,单诺沙星0.002 μg/mL,沙拉沙星和氧氟沙星为0.04 μg/mL,二氟沙星和奥比沙星为0.02 μg/mL,依诺沙星、麻保沙星为0.4 μg/mL,各组分回收率在97%～100.2%,相对标准偏差为0.2%～2.9%.     

液相色谱-串联质谱法检测水产品中15种喹诺酮类药物残留量

建立了液相色谱-串联质谱技术同时检测水产品中15种喹诺酮类药物(氟罗沙星、氧氟沙星、依诺沙星、诺氟沙星、环丙沙星、恩诺沙星、洛关沙星、单诺沙星、奥比沙星、双氟沙星、沙拉沙星、司帕沙星、口恶喹酸、萘啶酸、氟甲喹)残留量的方法.试样中残留的喹诺酮类药物采用乙腈提取,提取液经正已烷液液分配脱脂后,以强阳离子固相萃取小柱净化,液相色谱.串联质谱法测定.对液/质分离条件与样品前处理条件进行了优化,并对喹诺酮类药物在分析过程的稳定性进行了研究.15种喹诺酮类药物在1.0～100 μg/L范围内线性关系良好,相关系数为0.9924～0.9992.在0.002～0.04 mg/kg浓度范围内,平均加标回收率在79.9%～93.8%;相对标准偏差为4.8%～14.6%.方法可满足水产品中喹诺酮类药物多残留检测与确证的需要.     

高效液相色谱-串联质谱法测定蜂蜜中残留的19种喹诺酮类药物

建立了高效液相色谱-电喷雾串联质谱联用测定蜂蜜中恩诺沙星、环丙沙星、诺氟沙星、氧氟沙星、双氟沙星、恶喹酸、氟甲喹、沙拉沙星、司帕沙星、丹诺沙星、氟罗沙星、马波沙星、伊诺沙星、奥比沙星、吡哌酸、培氟沙星、洛美沙星、西诺沙星和萘啶酸等19种喹诺酮类药物残留的方法。比较酸性溶液阳离子固相萃取(PCX柱)、近中性缓冲溶液反相固相萃取（HLB柱）和碱性溶液阴离子固相萃取(PAX柱)3种不同提取净化方法的提取效果,最终选择使用碱性溶液溶解蜂蜜样品,强阴离子固相萃取柱一步富集净化。以甲醇和0.1%甲酸溶液作为流动相,C18作为分析色谱柱,采用梯度洗脱方式进行液相色谱分离,选择离子反应监测模式检测19种喹诺酮类药物,内标方法定量。在1～100 μg/L范围内,19种喹诺酮类药物的线性相关系数均大于0.991。通过实际样品的添加回收试验,方法的定量限（S/N=10）为1.0 μg/kg,3个添加水平的回收率为71%～118%,相对标准偏差为4.2%～6.7%。     

高效液相色谱-串联质谱法测定动物组织中的16种喹诺酮类药物残留

建立了动物组织样品中萘啶酸、恶喹酸、氟甲喹、诺氟沙星、依诺沙星、环丙沙星、洛美沙星、丹诺沙星、恩诺沙星、氧氟沙星、沙拉沙星、二氟沙星、麻保沙星、培氟沙星、司帕沙星、奥比沙星等16种喹诺酮类兽药多残留量的高效液相色谱-串联质谱测定方法。用酸性乙腈萃取样品中的16种喹诺酮类药物残留,然后用正己烷脱脂,旋转蒸发浓缩,以Inertsil C8-3色谱柱分离,在正离子模式下以电喷雾电离串联质谱进行测定。在10，50，100 μg/kg 3个加标水平下进行了验证试验,方法的线性范围为10~100 μg/kg,平均回收率为62.4%~102%,相对标准偏差为1.4%~11.9%。该方法简便、快速、准确,各项技术指标满足国内外法规的要求,可用于鸡肉、鸡肝和鱼肉等动物组织样品中喹诺酮类药物多残留的确证检测。     

反相高效液相色谱法同时测定4种氟喹诺酮类药物在鸡可食性组织中的残留

 建立了一种可同时测定鸡可食性组织中环丙沙星、达氟沙星、恩诺沙星及沙拉沙星等多种残留的反相高效液相色谱 -荧光分析法。鸡的肌肉、皮和脂、肝、肾等4种组织经不同pH值的磷酸二氢钾缓冲溶液匀浆提取,上清液通过C18固相萃 取柱净化,以流动相洗脱。洗脱液经液相色谱分离后,用荧光检测器进行检测(激发波长280 nm, 发射波长450 nm),外标 法定量。对鸡的4种组织进行添加回收率测定,结果显示方法在添加水平为20~300 μg/kg时药物的回收率约为53.9%～93.4%,批间回收率测定值的相对标准偏差低于23%;环丙沙星、恩诺沙星、沙拉沙星 的定量检出限为20 μg/kg,达氟沙星为4μg/kg。方法简单、快速，能满足常规兽药残留检测的需要。     

高效液相色谱检测动物肌肉组织中7种喹诺酮类药物的残留

本研究建立了同时检测动物肌肉组织中环丙沙星、单诺沙星、恩诺沙星、沙拉沙星、二氟沙星、恶喹酸、氟甲喹7种喹诺酮类药物的HPLC-FLD检测方法。动物组织样品用磷酸盐水溶液提取,HLB固相萃取柱净化,采用甲酸水溶液-乙腈体系作为流动相,梯度洗脱,程序波长荧光检测器检测。方法的线性范围为0.3~100μg/L,相关系数(r)大于0.9989;检出限为0.1~0.3μg/kg,定量限为0.3~1.0μg/kg;7种喹诺酮类药物在鸡肉和猪肉的平均回收率分别为70.4%~102.1%和79.6%~105.8%;相对标准偏差分别为1.1%~8.9%和1.3%~9.3%。     

反相高效液相色谱/质谱法同时测定鸡肉中5种喹诺酮药物残留

采用反相高效液相色谱/四级杆串联质谱(RP-HPLC/MS/MS)同时测定鸡肉中的５种喹诺酮药物(quinolones,QNs).均质后的鸡肉样品采用磷酸盐缓冲溶液和乙腈的混和溶液提取.提取液经正己烷液-液分配(LLP)去除脂肪后,用C18固相萃取(SPE)柱净化,氨化甲醇洗脱,洗脱液用氮气吹干,流动相定容后,分析物采用LC/MS/MS电喷雾电离(ESI),正离子,多反应监测(MRM)模式检测,外标法定量.在添加浓度2.5～10μg/kg范围内,５种QNs的回收率在79.8%～95.1%之间;相对标准偏差(RSD)均小于11.7%.环丙沙星、丹诺沙星、恩诺沙星检出限(LOD)为0.5 μg/kg,沙拉沙星为1.0 μg/kg,氟甲喹为0.1 μg/kg.     

鸡肉中11种喹诺酮类药物多残留的高效液相色谱检测

建立了用荧光检测器同时测定11种喹诺酮类药物(包括诺氟沙星、培氟沙星、环丙沙星、恩诺沙星、氧氟沙星、达氟沙星、洛美沙星、二氟沙星、沙拉沙星、恶喹酸和氟甲喹)在鸡肉中的多残留的高效液相色谱检测方法。鸡肉样品用10%三氯乙酸-乙腈(体积比为7∶3)提取两次并稀释,随后用反相固相萃取柱净化。采用Hypersil BDS-C18色谱柱分离,以乙腈和水为流动相梯度洗脱,荧光检测器用程序编程检测波长检测。11种喹诺酮类药物标准曲线的线性范围为5～1200 μg/L,相关系数大于0.998。在高、中、低三个添加水平下的回收率为56%～119%,批内相对标准偏差为0.4%～16.1%,批间相对标准偏差为1.4%～23.0%。检出限和定量限分别为1～23 μg/kg和4～40 μg/kg。该方法快速、灵敏,达到了兽药残留检测的要求。     

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%).     

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.     

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.     

Synthesis of pyrrolo[1,2-a]pyrazines and pyrazino[1,2-a]indoles by Curtius reaction in Morita-Baylis-Hillman derivatives

Synthesis of substituted pyrrolo[1,2-a]pyrazines and pyrazino[1,2-a]indoles from the Morita-Baylis-Hillman derivatives of acrylates via saponification followed by Curtius reaction is described.     

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.