中草药中有机氯农药和拟除虫菊酯农药残留量的测定

建立了中草药中11种有机氯农药和8种拟除虫菊酯农药的残留气相色谱分析方法。样品用含30％丙酮的乙腈提取,用正己烷进行液液分配,提取液用弗罗里硅土柱净化,采用兰州化物所的农残Ⅱ号毛细管柱分离,用GC-ECD同时检测。在两个水平添加时的回收率(n=5)分别为78．6％～119．7％和86．5％～114．0％,相对标准偏差分别为3．6％～8．7％和4．4％～10．2％。该方法的检出限为：有机氯农药0．005mg／kg,拟除虫菊酯农药0．01mg／kg。方法用于江西中草药样品中农药残留测定,结果满意。     

中药材中5种拟除虫菊酯农药残留量的测定

研究中药材中5种拟除虫菊酯农药残留量的测定方法。用石油醚-丙酮混合溶剂超声提取，固相萃取法净化，用气相色谱-电子捕获检测器（ECD）测定。5种拟除虫菊酯农药在3种代表性中药材的加标回收率为72．6％-135．0％，相对标准偏差为3．6％。27％；方法的检出限为0．001—0．005μg／g。方法灵敏度高，选择性好，操作较为简便，适用于植物性（根、茎类）药材中5种拟除虫菊酯农药残留量的测定。     

土壤中多种有机氯及拟除虫菊酯类农药的GC-ECD测定

气相色谱法同时测定土壤中多种有机氯及拟除虫菊酯类农药。对土壤的分析结果：有机氯农药的检出限0．001～0、003μg／mL，拟除虫菊酯类农药检出限0.008～0．02μg／mL，线性相关系数0．9978～0．9999。用y（石油醚）：V（丙酮）=3：1超声波提取，有机氯农药回收率94．2％～124．0％，相对标准偏差为3．3％～8．8％（n=5）；拟除虫菊酯类农药回收率95．2％～118．3％，相对标准偏差为5．7％～7．1％（n=5）；方法适用于土壤样品中农药残留测定。     

柱后光化学反应荧光检测高效液相色谱法测定茶叶中的五种菊酯类农药残留

建立了柱后光化学反应荧光检测高效液相色谱法测定茶叶中菊酯类农药残留的方法。采用Hypersil ODS色谱柱，以乙腈／水为流动相、梯度洗脱进行分离。用自制的光化学反应器作为荧光衍生装置，优化了柱后光化学反应的实验条件，并用于茶叶样品中菊酯类农药残留的测定。方法的检出限为0．012～0．048μg／g(干重)；线性范围0．040～8．0μg／g，相对标准偏差3．4％～6．4％(0．1mg／L，n=8)。     

应用搅拌棒吸附萃取-热脱附-气相色谱-质谱测定烟叶和茶叶中拟除虫菊酯类农药残留

应用搅拌棒吸附萃取(SBSE)技术分别萃取烟叶和茶叶中的5种拟除虫菊酯,并利用热脱附系统将萃取到的物质进行热脱附,然后通过气相色谱-质谱联用仪(GC-MS)进行分析测定。实验过程中对影响SBSE的因素及影响热脱附的条件进行了优化。在优化条件下,采用外标法分别对烟叶和茶叶中的5种拟除虫菊酯类农药残留进行了定量分析。结果表明,烟叶中5种拟除虫菊酯的检出限范围为3.3~11.4 ng,加标回收率为94.8%~103.4%,6次测定的相对标准偏差（RSD）为5.3%~8.6%;茶叶中5种拟除虫菊酯的检出限范围为4.2~10.5 ng,加标回收率为98.2%~110.1%,6次测定的RSD为5.0%~9.6%。实验证明该法具有较高的准确度、灵敏度和较好的重现性,可用于烟叶和茶叶中拟除虫菊酯类农药残留的快速分析测定。     

气相色谱法同时测定土壤中10种有机氯农药残留量

运用气相色谱及内标法定量测定土壤中的七氯、艾氏剂、六六六及滴滴涕类等10种有机氯农药残留。测定结果的相对标准偏差为4．2％～22．0％，回收率为70．3%-119．0％。通过实样分析验证了方法的适用性。     

毛细管气相色谱法测定中药材中多种拟除虫菊酯农药残留量

研究了气相色谱法测定中药材中多种拟除虫菊酯类残留量的分析方法。样品经正己烷．丙酮混合液[V（正己烷）：V（丙酮）=1：1]提取，氟罗里硅土层析柱净化，采用毛细管色谱柱分离，GC-ECD可同时测定8种拟除虫菊酯类农药残留量，回收率为76．6％～104．2％。     

气相色谱-质谱法快速筛选测定浓缩苹果汁中105种农药残留量

采用硅藻土柱层析法对样品中的农药进行提取及净化后，用气相色谱—质谱法在选择离子监测模式下进行快速测定，以保留时间和特征离子定性定量；采用此方法测定了包括有机氯农药、有机磷农药、氨基甲酸酯农药、拟除虫菊酯农药、三嗪类农药在内的105种农药，大多数农药的线性范围为0.05～10mg／kg，相关系数大于0.99；90％以上农药在0．2mg／kg添加水平的平均回收率在70％～110％的范围内。     

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。     

气相色谱-电子捕获检测器同时测定茶叶中有机氯及拟除虫菊酯类农药残留

在超声波辅助下,以正己烷-二氯甲烷（1：1,V／V）混合溶剂提取样品,提取液用弗罗里硅土和中性氧化铝混合柱净化,用气相色谱-电子捕获检测器（GC-ECD）同时测定茶叶中18种有机氯和9种拟除虫菊酯类农药残留。有机氯农药在0.001-0.2μg／mL,拟除虫菊酯类农药在0.005-1.0μg／mL范围内线性良好。有机氯农药在0.04、0.01μg／mL两个添加水平的回收率分别为89.5％-113.2％和80.0％-112.7％,相对标准偏差分别为3.82％-9.64％和5.32％-13.8％。拟除虫菊酯在0.2、O.05μg／mL两个添加水平的回收率分别为97.5％-129.6％和87.3％-110.2％,相对标准偏差分别为3.78％-10.72％和3.02％-13.84％。本方法快速、灵敏、准确、可靠,用于江西茶叶样品中有机农药残留测定,获得较好结果。     

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.