固相萃取-超高效液相色谱-串联质谱法测定畜禽饮用水中23种抗生素和3种β-受体激动剂

建立了固相萃取-超高效液相色谱-串联质谱同时测定畜禽饮用水中4类23种抗生素(磺胺类、喹诺酮类、四环素类、氯霉素类)和3种β-受体激动剂(克伦特罗、莱克多巴胺、沙丁胺醇)的分析方法。样品经高氯酸调节pH至5.0,加入乙二胺四乙酸二钠(Na2EDTA),HLB固相萃取柱富集,用超高效液相色谱-质谱联用仪分时段多反应监测离子模式分析,外标法定量抗生素,内标法定量β-受体激动剂。23种抗生素和3种β-受体激动剂的空白基质加标回收率为50.7%~104.6%,相对标准偏差(n=3)为2.6%~8.8%。23种抗生素和3种β-受体激动剂的线性关系良好,相关系数均大于0.994,检出限为0.01~0.20 ng/L。通过该方法分析了北京地区36家规模化畜禽养殖场畜禽饮用水中的抗生素和β-受体激动剂,检出了多种抗生素,并对含量进行了定量计算。     

液相色谱-串联四极杆质谱法对动物源基质中β2-受体激动剂的检测

β2-受体激动剂苯乙胺类药物(phenethylamines,PEAs)具有苯乙醇胺结构骨架,苯环上连接有碱性的β-羟胺侧链.目前使用的β2-受体激动剂已有30多种,我国禁止所有β2-受体激动剂用于养殖业.农业部235号公告<动物性食品中兽药最高残留限量>规定在所有食用动物的可食组织中不得检出此类药物.本文在已有方法的基础上进行了改进,利用Agilent 6410A串联四极杆质谱同时测定了11种β2-受体激动剂.实验结果表明该方法快速、简单、灵敏度高,可达到出口欧盟和日本的检测要求.     

猪尿中7种β-肾上腺素能激动剂残留检测的超高效液相色谱-串联质谱法研究

β-肾上腺素能激动剂(简称β-激动剂),有强而持久的松弛支气管平滑肌的作用.在畜牧生产中使用,可明显提高动物的瘦肉率,但使用剂量过大,则会对动物和人(间接)的肝脏、肾脏等器官产生相当大的毒害作用[1].     

高效液相色谱-线性离子阱质谱法测定畜禽肌肉中β_2-受体激动剂及β-阻断剂类药物残留

利用高效液相色谱-线性离子阱质谱(HPLC-ITMS)以同位素稀释技术测定了肌肉组织中23种β2-受体激动剂及5种β-阻断剂.肌肉样品经5%的三氯乙酸溶液酸解提取,以弱阳离子固相萃取柱进行净化.以甲醇和含0.1%甲酸的水溶液为流动相在液相色谱柱上梯度洗脱分离,采用ESI源正离子模式在选择离子监测(SRM)模式下进行扫描.以9种经氘代同位素标记的β2-受体激动剂为内标进行定量.猪肉中23种β2-受体激动剂及5种β-阻断剂的线性范围为5～200μg/L,相关系数(r)大于0.995,各化合物在肌肉中的检出限均能达到0.2μg/kg.以空白猪肉样品进行的加标水平为5、10、20μg/kg的加标回收试验,各化合物的回收率在47.3%～123.7%之间,相对标准偏差在3.2%～25.7%之间.对猪肉样品和鸡肉样品进行了测定,得到了满意的结果.该方法灵敏度高,定性准确,可以用于畜禽肌肉中β2-受体激动剂和β-阻断剂类药物残留的确证检测.     

气相色谱-质谱法测定肝、肾和肉中β2-受体激动剂残留量

本文用气相色谱-质谱法同时测定肝、肾和肉中β-受体激动剂中10种β2受体激动剂残留。样品经粉碎、酶水解、沉淀蛋白质、液-液分配后,经SCX柱净化和TMS衍生化后,用美托洛尔(metoprolol)为内标,GC-MS测定。可同时测定11种β2-受体激动剂,检出限为0.002mg／kg。1实验部分1.1样品处理方法在10g经捣碎样品中,加入15mLpH5.2的乙酸钠缓冲溶液。添加120ng美托洛尔内标。加50μL的β-盐酸葡萄糖醛甙酶-芳基硫酯酶,于恒温箱中37℃培养18h。加入10mL0.1mol／L的高     

在线固相萃取-高效液相色谱-质谱法快速测定绵羊尿液中3种轭合态β-受体激动剂

采用双三元高效液相色谱和液相质谱联用(HPLC-MS/MS)建立了测定绵羊原始尿液及酶解后尿液中β-受体激动剂(沙丁胺醇、克伦特罗、莱克多巴胺)在线SPE(Turboflow)检测的方法。分别对Turboflow柱和分析柱条件进行优化,最终确定样品上样速率4 m L/min,进样体积100μL,样品净化时间0.5 min。本方法的回收率在91.3%~112.2%之间,线性范围为0.1~100μg/L,精密度RSD<1%,日间峰面积RSD<12%,说明方法的重现性和稳定性良好。在对酶解后的尿液检测中发现,对于苯酚类β-受体激动剂(沙丁胺醇、莱克多巴胺),酶解后的尿液中检出化合物含量明显高于未酶解样品,对苯胺类β-受体激动剂(克伦特罗)的影响不大。本方法只需对原始尿液或酶解后的尿液进行过膜处理,样品的在线净化、富集、柱平衡和最终分析可在15 min内完成,大大缩短了日常分析所需时间。本方法操作简单,可用于养殖动物β-受体激动剂大规模筛查。     

分子印迹固相萃取-超高效液相色谱-串联质谱法快速测定猪尿中15种β_2-受体激动剂残留

建立了分子印迹固相萃取(MISPE)-超高效液相色谱-串联质谱(UPLC-MS/MS)快速测定猪尿中15种β_2-受体激动剂的分析方法。分别优化了上样溶液的pH值、淋洗和洗脱溶液等MISPE净化条件及质谱条件。将猪尿样品离心,经MISPE柱上样,依次用水、乙腈、0.5%(v/v)乙酸乙腈溶液淋洗,10%(v/v)乙酸甲醇溶液洗脱,氮气吹干,0.1%(v/v)甲酸水-乙腈(9∶1,v/v)复溶;采用BEH C_(18)色谱柱分离,以乙腈-0.1%(v/v)甲酸水溶液为流动相,采用梯度洗脱,在电喷雾正离子多反应监测模式下外标法定量。考察了MISPE对15种β_2-受体激动剂的吸附特异性;猪尿中15种β_2-受体激动剂在0.1~20μg/L范围内线性关系良好(r~2≥0.992);检出限和定量限分别为0.03和0.1μg/L;15种β_2-受体激动剂的加标回收率为65.6%~115.0%,批内、批间相对标准偏差分别为0.57%~16.1%和1.11%~16.8%。该方法操作简单、快速、灵敏度高、特异性好。     

UPLC-MS/MS结合SPSS研究多种β_2-受体激动剂的萃取效率及快速检测方法

研究了液液萃取提取,超高效液相色谱-串联质谱(UPLC-MS/MS)测定水中14种β_2-受体激动剂的方法。通过单因素与正交试验研究水的pH、有机溶剂种类、振荡时间、萃取温度等因素对水中β_2-受体激动剂萃取效率的影响,用SPSS对数据进行分析。该方法 14种β_2-受体激动剂的检出限为0.03~0.2 ng/mL,添加回收率为62.8%~88.3%,RSD为3.4%~13%。方法可用于β_2-受体激动剂的多残留检测研究。     

超高效液相色谱-串联质谱法测定畜禽毛发中8种β-受体激动剂

采用超高效液相色谱串联质谱(UPLC-MS/MS)法,通过优化β-受体激动剂在毛发中的提取、净化等前处理过程,建立了一种测定畜禽毛发中8种β-受体激动剂含量的方法。样品经β-葡萄糖醛苷酶/芳基硫酸酯酶酶解,2%甲酸-乙腈溶液提取,MCX固相萃取小柱净化,通过C18色谱柱分离,电喷雾串联质谱多反应监测模式测定。结果表明,8种β-受体激动剂在0.2～10μg/L范围内线性关系良好,相关系数均大于0.991,回收率在71.5%～114.3%之间,相对标准偏差为1.2%～13%。沙丁氨醇、特布他林、氯丙钠林、莱克多巴胺、拖布特罗和喷布特罗的检出限为0.5μg/kg,西马特罗和克伦特罗的检出限为1.0μg/kg。该方法适用于畜禽毛发中8种β-受体激动剂的定性定量分析。     

超高压液相色谱-串联质谱法测定畜禽粪便中3种β-受体激动剂残留

建立了畜禽粪便中3种β-受体激动剂药物残留的超高压液相色谱-串联四极杆质谱联用仪测定方法。样品酶解后经高氯酸溶液净化,调节p H值至碱性,乙酸乙酯提取,净化浓缩后以流动相定容,用超高压液相色谱-质谱联用仪检测,内标法定量。3种β-受体激动剂在0.5~20.0μg/L范围内线性关系良好,相关系数均大于0.998。畜禽粪便中3种β-受体激动剂的加标回收率为80.3%~110.2%,相对标准偏差为3.0%~7.7%,检出限(S/N=3)为0.04~0.07μg/kg。     

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.     

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.     

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.     

Catalyst free,visible-light promoted photoaddition reactions between C60 and N-trimethylsilylmethyl-substituted tertiary amines for synthesis of aminomethyl-1,2-dihydrofullerenes

An efficient and benign method for the preparation of aminomethyl-substituted fullerenes has been developed. The process, involving catalyst free, visible-light irradiation of 10% EtOH-toluene solutions containing fullerene C₆₀ and N-trimethylsilylmethyl-substituted amines by using a 20 W compact fluorescent lamp, leads to formation of aminomethyl-substituted fullerene adducts in a highly efficient manner. The photoaddition reaction takes place via a pathway initiated by visible light absorption by C₆₀, followed by SET from the amine to the triplet excited state of C₆₀. Ethanol-promoted desilylation of the resulting a minimum radical then generates the corresponding α-amino radical which couples with the C₆₀ radical anion to form the anion precursor of the fullerene adducts. The new approach using visible-light takes place under mild conditions and it does not require the use of photocatalysts. Thus, the method developed in this effort could broadens the range of functionalized fullerene derivatives that can be readily prepared.     

Highly efficient and stereoselective cycloaddition of nitrones to indolyl- and pyrrolylacrylates

The reactions of various nitrones with indolyl- and pyrrolylacrylates proceeds regioselectively with high diastereoselectivity in the case of aldonitrones, and represents an effective method for obtaining new indolyl- and pyrrolyl-substituted isoxazolidine carboxylates stabilized by weak (CH?O) and moderate (NH?N) strength intramolecular hydrogen bonding. The resulting cycloadducts exhibit promising in vitro anti-influenza activities.     

Transition metal-free direct amination of benzoxazoles using formamides as nitrogen sources

A transition metal-free method for the direct amination of benzoxazoles using formamides as nitrogen sources is reported, which was mediated by an inexpensive and environmentally friendly tetrabutylammonium iodide/tert-butyl hydroperoxide system and gave the 2-aminobenzoxazole derivatives with moderate to good yields.     

l-Proline-catalyzed five-component domino reaction leading to multifunctionalized 1,2,3,4-tetrahydropyridines

Multifunctionalized 1,2,3,4-tetrahydropyridines are concisely synthesized in good yields via l-proline-catalyzed or l-proline/FeCl₃-cocatalyzed one-pot multicomponent reactions (MCRs). The MCRs involve a domino hydroamination/prins reaction/Mannich-type reaction/intramolecular dehydration-cyclization process. The molecular structure of 5baa, one of multifunctionalized 1,2,3,4-tetrahydropyridines, was confirmed by single-crystal X-ray diffraction.     

Exploring the scope of the Gewald reaction: Expansion to a four-component process

An efficient four-component reaction was developed to take advantage of the reactivity of the 2-aminothiophene-3-carbonitrile functionality, which is obtained during the classical three-component Gewald reaction. Various α-methylene bearing ketones were reacted with malononitrile, elemental sulfur, and aryl/heteroarylnitrile derivatives in t-BuOH/NaOH to afford 2-arylthieno[2,3-d]pyrimidin-4-amines in high yields. Preliminary studies revealed the photophysical properties of the products and their potential for use as metal sensors.