固相萃取-HPLC法测定蜂蜜中残留的10种磺胺类药物

研究了用固相萃取-高效液相色谱法同时测定蜂蜜中10种磺胺类药物残留量的方法。样品经三氯甲烷溶液提取,过Oasis HLB C18固相萃取柱净化,用乙腈洗脱10种磺胺,反相高效液相色谱-紫外检测器测定。检测波长为270nm,柱温45℃．流动相：磷酸水溶液-乙腈梯度洗脱．该方法前处理简单,梯度洗脱分离效果和重现性好,在0．010～1．0mg／kg添加水平,10种组分的回收率在86．5％～100．8％之间,室内相对标准偏差在3．5％～8．1％之间,线性范围为0．010～10μg／mL,检出限为0．005mg／kg。该方法快速、灵敏、专属,可用于食品中磺胺类药物残留量的常规检测。     

高效液相色谱法测定动物源食品中磺胺类药物残留量

试样中残留磺胺药物用乙腈提取并经正己烷萃取和通过碱性氧化铝层析柱进行净化。所得乙腈-水（30＋70）洗脱液用于高效液相色谱法测定。采用C18色谱柱（250mm×4．6mm）作固定相,以乙腈（A）及乙腈＋乙酸＋水（20＋1＋79）的混合液（B）按不同比例混合液作流动相进行梯度淋洗使5种磺胺药物分离,最后在270nm波长处作紫外检测,所测定的磺胺药物的质量浓度与其峰面积之间在0．05～1.00mg·L^-1范围内呈线性关系。方法的测定下限（S／N=10）为0．04mg·kg^-1,以猪肉样品为基体加入3种药物的标准溶液进行回收试验,测得回收率在73．65％～93．45％之间。     

高效液相色谱法测定盐酸噻吩诺啡有关物质的方法研究

建立盐酸噻吩诺啡药物有关物质检查的液相色谱方法。采用ZORBAX—C18色谱柱，流动相为甲醇-乙腈-（0．002mol／L KH2PO4—0．3％三乙胺，pH3），检测波长为220nm。该方法能较好地分离药物与有关物质，样品在测定浓度范围内线性关系良好，药物纯度为99．0％以上。对药物中的未知杂质用质谱法鉴定，确认杂质来源。方法可用于盐酸噻吩诺啡药物的有关物质检测。     

多功能柱净化-高效液相色谱法同时检测小麦中雪腐镰刀菌烯醇和脱氧雪腐镰刀菌烯醇

建立了小麦中雪腐镰刀菌烯醇（NIV）和脱氧雪腐镰刀菌烯醇（DON）的高效液相色谱同时检测方法。样品采用乙腈-水（体积比85：15）混合溶剂进行提取．通过多功能净化柱（MFC）进行一次性净化，以C18柱为分离柱，水-乙腈-甲醇（体积比90：5：5）混合溶剂为流动相进行高效液相色谱分离和检测。在小麦样品中，本方法在0．2～5μg／g添加范围内的凹收率为87％～99％；相对标准偏差为1．5％～8．3％；DON和NIV的检出限分别为0．12和0、16μg／g（5／N=3）。     

固相萃取-梯度洗脱高效液相色谱法同时检测饲料中十三种磺胺类药物

建立了一种同时检测饲料中十三种磺胺类药物含量的方法,样品用磷酸盐缓冲液提取,HLB固相萃取小柱净化,梯度洗脱-HPLC分析,方法定量下限为0．5mg／kg,在0．5～10．0mg／kg添加水平上的回收率为63．6％～118．2％,相对标准偏差4．78％～17．24％,方法简便．适用于饲料中低含量磺胺类药物检测．     

反相高效液相色谱法用于地钱中黄酮类化合物的分离与测定

采用反相高效液相色谱,在RP—C18柱上以乙酸-甲醇-乙腈-磷酸-水为多元流动相,等度洗脱,在30min内对地钱的黄酮提取物进行分离与测定,检测波长350nm,流速0．60mL／min,采用校准曲线法对实际样品中的芹菜素、槲皮素和木犀草素进行定量分析。结果表明：平均加标回收率96．79％～101．13％．相对标准偏差0．66％～1．52％．     

生鲜牛乳中农药多残留分析方法研究

本文报道生鲜牛乳中不同类型农药的多残留同时快速检测方法。样品经乙腈、丙酮(1：1,V／V)混合溶剂提取,离心,C18固相萃取柱纯化、富集,采用毛细管气相色谱法,电子捕获检测器检测,进行定性、定量检测有机氯、有机磷和拟除虫菊酯等14种农药的残留量。本法的加标回收率为78．5％～104．6％(敌敌畏为63．2％);检出限为0．5～14．0μg／L;线性相关系数,r^2≥0．9922。     

多功能柱净化-高效液相色谱法检测谷物中的玉米赤霉烯酮

建立了玉米和小麦中玉米赤霉烯酮（ZEN）的多功能柱净化-高效液相色谱检测方法。样品经乙腈-水混合溶剂（V（乙腈）：V（水）=84：16）提取，通过多功能净化柱（MFC）进行一次性净化，以Symmetry^R C18柱为分离柱，甲醇-水（V（甲醇）：V（水）=68：32）为流动相进行高效液相色谱分离和检测。玉米赤霉烯酮的质量浓度在0．01～4．0μg／mL范围内呈良好线性，相关系数为0．9996。检出限为0．04μg／g，在0、04—5．0mg／kg添加范围内的回收率为87．5％～98．6％，相对标准偏差为1．5％～8．3％。     

高效液相色谱法测定动物组织中8种磺胺类药物残留量

提出了一种快速、准确地同时测定动物组织中磺胺类药物残留量的检测方法。样品中加入无水硫酸钠后，用乙腈均质、提取，在离心后的沉淀物中加入乙腈，再次提取，合并乙腈提取液。提取液用乙腈饱和正己烷溶液净化，去除脂肪和杂质，用高效液相色谱方法进行测定。通过优化色谱条件，利用紫外检测器(VWD)或二极管阵列检测器(DAD)对8种磺胺类药物残留进行同时测定，测定结果的相对标准偏差为5.1％～12.8％，平均回收率为62.7％～105．1％，检出限为10μg/kg。     

大豆中6种磺酰脲类除草剂残留量的高效液相色谱-质谱法测定

建立了LC—MS选择离子监测(SIM)同时检测大豆中6种磺酰脲类除草剂残留量的方法。样品经乙腈提取，正己烷液-液分配，Florisil柱净化，然后采用HPIE—ESI( )-MS测定。6种磺酰脲类除草剂在25～1000μg／L范围内线性良好，相关系数为0．9996～0．99977在0．02～1．0mg／kg范围内，平均加标回收率在72％～99％之间，相对标准偏差为0．9％～7．7％。方法的检出限低于10μg／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.     

Toward new camptothecins. Part 6: Synthesis of crucial ketones and their use in Friedländer reaction

In the context of the preparation of camptothecin and luotonin A analogs, the synthesis of some key keto-precursors and their use in Friedländer condensation are described. This paper also focuses on the stability of these keto intermediates and emphasizes the major differences between indolizinones and pyrroloquinazolinones series. Noteworthy is also the report of some original structures isolated as by-products of some experiments.     

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.