限进印迹柱在线净化/液相色谱-串联质谱法检测动物源食品中克伦特罗与莱克多巴胺残留量

利用针对β-受体激动剂的限进型分子印迹整体柱,通过切换阀的组合和在线净化条件的优化,建立了检测动物源食品中克伦特罗和莱克多巴胺残留的在线净化/液相色谱-串联质谱法。样品经酶解和乙酸铵缓冲液提取后,由在线分子印迹柱净化,CAPCELL PAK C18色谱柱(2.1 mm×100 mm,5μm)分离,多反应监测模式测定,内标法定量。克伦特罗和莱克多巴胺的定量下限分别为0.02μg/kg和0.09μg/kg。在猪肉、牛肉、香肠和奶粉中添加0.05~0.20μg/kg克伦特罗和0.5~2.0μg/kg莱克多巴胺,回收率为84.0%~103.8%,相对标准偏差小于12%。     

在线固相萃取-液相色谱-串联质谱法测定动物源食品中阿维菌素和伊维菌素的残留量

利用在线固相萃取系统,通过萃取柱的选择和在线洗脱条件的优化,建立了测定动物源食品中阿维菌素和伊维菌素残留量的在线固相萃取-液相色谱-串联质谱法。2.50g样品经5mL乙腈和5mL的0.15%(体积分数)三乙胺溶液提取,采用HySphere C_(18) HD固相萃取柱对提取液进行在线净化。分析物经ZORBAX SB-C_(18)色谱柱(2.1mm×15mm,1.8μm)分离,采用乙腈和含0.2%(体积分数)甲酸的10mmol·L~(-1)乙酸铵溶液进行梯度洗脱。质谱分析采用电喷雾正离子源和多反应监测模式。阿维菌素和伊维菌素的质量浓度在10μg·L~(-1)内与峰面积呈线性关系,测定下限(10S/N)均为5.0μg·kg~(-1)。在猪肉、牛肉和香肠样品中进行加标回收试验,阿维菌素和伊维菌素的加标回收率在74.8%~96.5%之间,测定值的相对标准偏差(n=6)不大于11%。     

超高效液相色谱-串联质谱法测定鸡皮及脂肪组织中抗球虫类药物残留

建立了检测鸡的皮和脂肪中抗球虫类药物的超高效液相色谱-串联质谱分析方法。样品采用甲醇、乙腈、乙酸(4∶1∶0.05;V/V)混合溶液提取,提取液经Sep-Pak tC18固相萃取柱富集净化,在电喷雾正离子模式下,以多反应监测模式采集数据,进行定性与定量分析。结果表明,常山酮和氯苯胍的检出限均为7.0μg/kg,定量限为20μg/kg;盐霉素、莫能菌素、甲基盐霉素、马杜霉素和拉沙洛菌素的检出限均为5.0μg/kg,定量限为15.0μg/kg。本方法在15~200μg/kg添加浓度范围内的回收率为75%~110%,日内相对标准偏差≤12.8%,日间相对标准偏差≤13.4%。     

液相色谱-串联质谱法测定育肥猪配合饲料中的阿奇霉素

通过对提取溶剂、净化方法及色谱-质谱条件的优化,建立了配合饲料中阿奇霉素(AZM)的液相色谱-串联质谱测定方法。样品经乙腈超声波提取,MCX固相萃取柱净化,BDS Hypersil C_(18)(2.4μm,100 mm×2.1 mm)色谱柱分离,以甲醇-0.05 mol/L乙酸铵水溶液为流动相梯度洗脱,正离子模式电离,多反应监测模式检测,同位素内标法定量。在优化条件下,AZM在1~250μg/L范围内线性关系良好,相关系数(r~2)为0.999 1,检出限(S/N≥3)为2.8μg/kg,定量下限(S/N≥10)为8.4μg/kg;在0.5,1,5,10 mg/kg加标水平下,回收率为87.0%~106.6%,批内相对标准偏差为0.58%~5.4%,批间相对标准偏差为3.1%~5.4%。该方法准确、灵敏,选择性强,基质干扰小,可用于配合饲料中AZM的测定。     

高效液相色谱法同步检测牛奶中替米考星、泰乐菌素和螺旋霉素残留量

研究了牛奶中替米考星、泰乐菌素和螺旋霉素残留量的液相色谱同步测定方法。方法采用ZORBAX Eclipse XDB C18(5μm,150 mm×4.6 mmi.d)反相色谱柱,以甲醇为提取液,以SCX因相萃取柱为净化柱,流动相为0.05 mol/L磷酸二氢钠溶液 乙腈,梯度洗脱,流速1 mL/min,用二极管阵列检测器检测,替米考星和泰乐菌素的检测波长285 nm,螺旋霉素的检测波长232 nm,进样量100μL。替米考星、泰乐菌素和螺旋霉素的检出限分别为:30、20、40μg/kg,线性范围为20~800μg/kg,加标回收率为88.8%~99.4%,相对标准偏差为2.2%~8.9%。方法适用于牛奶中替米考星、泰乐菌素和螺旋霉素残留量的同步检测。     

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。     

免疫亲和层析净化-高效液相色谱法测定大米中桔霉素

大米样品经甲-醇10 mmol.L-1磷酸溶液(70+30)提取,提取液稀释过滤后经CitriTestTM免疫亲和柱层析净化后用高效液相色谱法测定其桔霉素的含量。以Kromasil 100-10 C18色谱柱(250 mm×4.6 mm,5μm)为分离柱,甲酸(1+99)溶液与乙腈以体积比1比1混合的溶液作流动相,采用荧光检测,激发波长为350 nm,发射波长为500 nm。必要时采用液相色谱-串联质谱法对结果作验证。桔霉素的质量浓度在5.0~500.0μg.L-1范围内与其峰面积呈线性关系,测定下限(10S/N)为10.0μg.kg-1。方法的回收率为73%~76%,相对标准偏差(n=8)为7.5%~11.8%。     

二维液相色谱法在线检测哈茨木霉发酵液中2460A含量

建立了在线检测哈茨木霉发酵液中微量2460A的二维液相色谱方法。利用Ultimate 3000双三元液相色谱仪,采用阀切换二维色谱技术,组合3根色谱柱实现2460A的在线净化、富集和含量检测。净化柱采用资生堂MF C8柱(10 mm×4.6 mm,5.0μm),富集柱采用资生堂MGC18柱(20 mm×4.6 mm,5.0μm),以水-甲醇为流动相,梯度洗脱,流速2.0 m L/min;二维分析柱采用Thermo Hypersil GOLD C18柱(250 mm×4.6 mm,5.0μm),以水-甲醇为流动相,梯度洗脱,流速1.0 m L/min;进样量1.0 m L;柱温40℃;检测波长424 nm。方法验证结果显示,2460A的线性范围为0.0025~10.0 mg/L(r=0.9981,n=8),检出限为1.2μg/L;定量限为2.5μg/L;方法回收率为88.0%~104.4%。     

改良的QuEChERS结合高效液相色谱-串联质谱同时测定水产品中7种阿维菌素类药物残留

建立了改良的QuEChERS结合高效液相色谱-串联质谱(HPLC-MS/MS)同时测定水产品中7种阿维菌素类药物(阿维菌素、伊维菌素、多拉菌素、塞拉菌素、乙酰氨基阿维菌素、莫西菌素和埃玛菌素)的分析方法。样品经0.2%(v/v)氨化乙腈提取,3 g无水硫酸镁和2 g无水硫酸钠除水剂和沉淀蛋白质,100 mg十八烷基硅烷(C18)和500 mg无水硫酸镁净化。以0.1%(v/v)甲酸乙腈(含5 mmol/L乙酸铵)-0.1%(v/v)甲酸水溶液(含5 mmol/L乙酸铵)为流动相,采用Varian Pursuit ULTRA C8色谱柱(100 mm×2.0 mm,2.8μm)进行分离。在加热电喷雾离子(HESI)源、正离子模式下采用多反应监测模式检测,基质匹配标准曲线外标法定量。阿维菌素、伊维菌素、多拉菌素、塞拉菌素、乙酰氨基阿维菌素和莫西菌素在2~200μg/L范围内、埃玛菌素在0.2~20μg/L范围内呈线性相关,相关系数(r)均≥0.997 2,水产品中阿维菌素类药物的加标回收率为71.6%~112.8%,相对标准偏差(RSD)为4.7%~13.1%,不同水产品的基质效应均小于15%。阿维菌素、伊维菌素、多拉菌素、塞拉菌素、乙酰氨基阿维菌素和莫西菌素的定量限均为5μg/kg,埃玛菌素的定量限为0.25μg/kg。该法操作简便,重复性好,适用于水产品中7种阿维菌素类药物残留量的同时测定。     

TurboFlow在线净化/液相色谱-串联质谱法测定水果蔬菜中多菌灵、吡虫啉、啶虫脒与甲基硫菌灵的残留量

建立了TurboFlow在线净化/液相色谱-串联质谱同时测定水果蔬菜中多菌灵、吡虫啉、啶虫脒和甲基硫菌灵残留的方法。样品用乙腈提取,经Cyclone-p在线净化柱净化后,将富集的分析物洗脱转至Betasil Phenyl-hexyl C18分析柱,经色谱分离后,电喷雾串联质谱检测。结果表明,4种农药在1~50 ng/mL范围内呈良好线性,相关系数均大于0.999 7。方法的定量下限(LOQ)为10μg/kg。4种农药在3个水平的加标回收率为80.3%~109.9%,相对标准偏差为1.5%~7.8%。     

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.