水产品中螺旋霉素、替米考星、泰乐菌素与北里霉素残留量的超高效液相色谱-紫外检测法同时测定

建立了水产品肌肉组织中螺旋霉素、替米考星、泰乐菌素、北里霉素同时测定的超高效液相色谱-紫外检测(UPLC-TUV)方法。样品经乙腈提取后,浓缩至近干,用4%NaCl溶解残渣,正己烷除脂,经固相萃取小柱净化,乙腈洗脱;以乙腈-25 mmol/L磷酸二氢铵(pH2.5,含10%乙腈)为流动相,以ACQUITYUPLC BEHC18为分离柱,柱温为45℃,流速为0.3 mL/min,紫外检测。方法在0.100~20.0 mg/L范围内呈线性相关,螺旋霉素、替米考星、泰乐菌素和北里霉素的相关系数分别为0.998 7、0.999 3、0.999 4和0.998 0。平均回收率为70%~102%,相对标准偏差为2.9%~11.2%,螺旋霉素、替米考星、泰乐菌素和北里霉素的检出限分别为25、25、50、75μg/kg。方法满足水产品肌肉组织中螺旋霉素、替米考星、泰乐菌素和北里霉素的残留量测定。     

肉食品中常见4种抗生素残留的高效液相色谱分析

建立了同时测定肉食品中泰乐菌素、替米考星、氯霉素、氟苯尼考的高效液相色谱方法,样品经乙腈提取,正己烷脱脂, HLB小柱净化后,以C18反相色谱柱为分离柱,甲醇－磷酸二氢钠缓冲溶液(pH 3.0,含体积比为10％的甲醇溶液）为流动相进行梯度洗脱,检测波长λ为275 nm.泰乐菌素、替米考星、氯霉素、氟苯尼考的线性范围是0.1～20.0 mg/L,相关系数分别为0.9987、0.9992、0.9985、0.9970.其平均回收率为75％～87%,相对标准偏差为1.35％～5.41％,泰乐菌素、替米考星、氯霉素、氟苯尼考的检出限分别为20、32、19、16μg/kg.方法满足肉食品中泰乐菌素、替米考星、氯霉素、氟苯尼考的残留量测定.     

固相萃取净化/高效液相色谱-串联质谱法测定饲料中7种大环内酯类药物含量

建立了添加剂预混合饲料、精料补充饲料、配合饲料和浓缩饲料中7种大环内酯类药物(替米考星、罗红霉素、螺旋霉素、泰乐菌素、红霉素、克拉霉素和阿奇霉素)含量的高效液相色谱-串联质谱(HPLC-MS/MS)测定方法。饲料样品经1%氨化乙腈提取,Oasis PRiME HLB固相萃取柱净化后,采用ACQUITY UPLC BEH C_(18)色谱柱(2.1 mm×100 mm,1.7μm)分离,以0.1%甲酸水-乙腈为流动相梯度洗脱,电喷雾离子源正离子模式下检测,外标法定量。结果表明,替米考星、螺旋霉素和红霉素的线性范围为0.5～50μg/L(r~20.99),罗红霉素、泰乐菌素、克拉霉素和阿奇霉素的线性范围为0.25～50μg/L(r~20.99);7种待测物的检出限(LOD)为1.25～2.5μg/kg,定量下限为2.5～5.0μg/kg,5、10、50μg/kg 3个加标浓度下的平均回收率为61.4%～103%,批内和批间相对标准偏差为0.43%～15%。该方法简便、快速、灵敏,基质干扰小,适用于各类饲料中大环内酯类药物的常规监测和定量测定。     

高效液相色谱串联质谱法测定牛奶中林可酰胺类和大环内酯类抗生素残留量的研究

建立了牛奶样品中洁霉素、氯洁霉素、红霉素、螺旋霉素、交沙霉素、泰乐菌素、竹桃霉素等7种林可酰胺类及大环内酯类药物残留量的确证方法。用乙腈萃取样品中7种林可酰胺类及大环内酯类抗生素,然后用正己烷脱脂,旋转蒸发仪浓缩,以Luna C18(2)色谱柱分离,在正离子模式下以电喷雾电离串联质谱仪进行测定。在20、50、200μg/kg 3个浓度水平进行验证试验,方法的线性范围为20~200μg/kg,总体平均回收率为74.5%~97.5%,相对标准偏差为2.7%~11.3%。该方法各项技术指标满足国内外法规的要求,可用于牛奶样品中林可酰胺类及大环内酯类抗生素残留量的确证检测。     

高效液相色谱法测定动物组织中四环素类抗生素残留量的研究

建立了动物组织中四环素、金霉素、土霉素、强力霉素、去甲基金霉素、甲烯土霉素和二甲胺四环素等7种四环素类抗生素残留量的液相色谱同时测定方法。方法采用Inertsil C8-3(5μm,250 mm×4.0 mm i.d)反相色谱柱,以pH 4.0的EDTA-Mcllvaine缓冲溶液为提取溶液,以HLB固相萃取柱为净化柱,流动相为甲醇+乙腈+0.01mol/L三氟乙酸(梯度洗脱),流速1.5 mL/min,检测波长350 nm,进样量100μL。方法的检出限为1.5~5.0μg/kg,测定低限为50μg/kg,线性范围为50~1200μg/kg,加标回收率为73.8%~103%,相对标准偏差为0.5%~8.5%。方法适用于动物肌肉、肝脏和肾脏组织中7种四环素类抗生素残留量的同时检测。     

高效液相色谱-串联质谱法同时检测动物性食品中多种大环内酯类药物

高效液相色谱-串联质谱法同时检测动物性食品中6种大环内酯类药物泰乐霉素、交沙霉素、柱晶白霉素、螺旋霉素、替米考星和红霉素残留。样品经乙腈提取,C18固相萃取柱净化,以0.1%(φ)甲酸-乙腈和0.1%(φ)甲酸-水作流动相梯度洗脱。电喷雾正离子MRM模式检测,罗红霉素作为内标。方法的定量下限为20μg/kg。在2~50μg/L范围内,峰面积与质量浓度成良好的线性关系,相关系数大于0.999。样品在20、100、200μg/kg添加水平的回收率为70%~110%,相对标准偏差为4.1%~10.3%(n=6)。方法灵敏、检出限低、实用性强。     

HPLC-MS/MS检测猪肉中六种大环内酯类抗生素

建立了以高效液相色谱-质谱(HPLC-MS/MS)检测猪肉中替米考星(TILM)、红霉素(ERY)、泰乐菌素(TYL)、吉他霉素(KIT)、罗红菌素(ROX)及交沙霉素(JOS)等6种大环内酯类抗生素的多残留分析方法.样品用乙腈提取后,经正己烷脱脂,过C18 柱净化,4%氨甲醇洗脱后经氮气吹干,采用多反应监测,对6种大环内酯类药物作定性和定量分析.在10～1000μg/L的范围内,6种药物线性良好(R>0.998).在50、100、200μg/Kg添加水平下,6种药物的回收率在62.2%～102%,相对标准偏差为2.7%～16%.替米考星和吉他霉素的检出限(S/N=3)为0.1μg/Kg,其它药物为0.05μg/kg.     

超高效液相色谱-串联质谱法对动物源食品中13种林可胺类及大环内酯类药物残留的检测

建立了动物源食品中林可霉素、克林霉素、吡利霉素、红霉素、泰乐菌素、螺旋霉素、替米考星、竹桃霉素、吉他霉素、克拉霉素、阿奇霉素、罗红霉素和交沙霉素13种林可胺类和大环内酯类药物残留检测的超高效液相色谱-串联质谱分析方法.动物组织样品经乙腈提取后,用正己烷去除脂肪等杂质,然后用Waters Acquity UPLC BEH C18色谱柱分离,以乙腈和50 mmol/L乙酸铵水溶液为流动相进行梯度洗脱,电喷雾正离子(ESI+)模式电离,多反应监测模式检测.结果表明:13种药物在5 ～200 μg/L范围内呈现良好的线性关系,相关系数R2均大于0.990,13种药物在动物组织中的检出限均为1 μg/kg,定量下限均为2.5 μg/kg.以2.5、25、100 μg/kg 3个水平进行回收实验,13种药物的回收率为72% ～104%,批内批间相对标准偏差为4.8% ～14.3%.     

高效液相色谱串联质谱法测定动物组织中林可酰胺类和大环内酯类抗生素残留

建立了动物组织样品中洁霉素、氯洁霉素、红霉素、螺旋霉素、交沙霉素、泰乐菌素、竹桃霉素等7种林可酰胺类及大环内酯类药物多残留的液/质联用确证方法。用乙腈萃取样品中7种林可酰胺类及大环内酯类抗生素,然后用正己烷脱脂,旋转蒸发仪浓缩,以LunaC18(2)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。方法的检出限为0.05~5.3μg/kg。在20、50、200μg/kg3个浓度水平进行验证实验,方法的线性范围为20~200μg/kg;总体平均回收率为70.3%~102%;相对标准偏差为2.4%~16.6%。本方法简便、快速、准确,各项技术指标满足国内外法规的要求,可用于动物组织样品中林可酰胺类及大环内酯类抗生素残留的确证检测。     

固相萃取-高效液相色谱法同时测定牛奶中13种磺胺残留

建立了固相萃取-高效液相色谱同时测定牛奶中13种磺胺类药物残留的方法。样品经乙腈溶液漩涡超声提取后,采用自制碱性氧化铝固相萃取小柱(SPE)净化,洗脱液减压浓缩至近干后用流动相溶解并定容,过PTFE滤膜后在Thermo Fisher Scientific ODS hypersil色谱柱上,以乙腈-20 mmol/L H3PO4溶液为流动相进行梯度洗脱,检测波长为270 nm。13种磺胺在50~5000μg/L范围内具有良好的线性,相关系数≥0.999,检出限为2.0~4.2μg/L,定量限为8.9~14.2μg/L。在20,50,100μg/L添加水平的加标回收率为79.0%~118.2%,相对标准偏差在2.7%~6.9%之间。方法能对牛奶中13种磺胺类药物残留实现准确定量分析。     

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.     

正丁胺对激光染料荧光谱影响的研究

用正丁胺作为碳源,采用射频辉光放电制备碳膜,选用激光染料R6G和聚乙二醇混合液作为蒸气源,采用单源热蒸发,在蒸发室与染料同时沉积得到混合膜,用拉曼光谱和红外光谱分析了碳膜的结构和键合方式,分析表明:碳膜中存在胺基团和氢原子.混合膜的荧光谱测量结果表明,认为正丁胺对染料荧光谱的影响是因为胺基和氢原子的存在.     

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.