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。     

凝胶渗透色谱净化一气相色谱分离同时测定糙米中50种有机磷农药残留

研究了同时检测糙米中50种有机磷农药残留的方法。用乙酸乙酯提取，凝胶渗透色谱净化，环己烷-二氯甲烷(50：50，V/V)作为流动相，气相色谱-氮磷检测器检测。方法检出限为0．001～0．089mg／kg；相对标准偏差为1．7％～18．9％；40多种农药平均回收率在70％～120％。     

气相色谱-质谱法同时测定番茄制品中拟除虫菊酯类农药残留

番茄制品经乙腈提取,盐析,氟罗里硅土固相萃取小柱净化,微池电子捕获检测器(μECD)负化学源质谱(NCI—MS)并联对净化液进行检测,一次进样可对番茄制品中的9种拟除虫菊酯类农药残留准确定量和确证。μECD回收率为87．6％～107．0％;相对标准偏差为5．5％～11．3％;检出限为0．0005～0．005mg／kg;负化学源选择离子(NCI-SIM)模式回收率为91．9％～109．7％;相对标准偏差为5．2％～12．7％;检出限为0．0005～0．005mg／kg(氯菊酯除外),两者之问没有显著的差别。该法快速、灵敏、准确,各项技术指标均满足农药残留检测的要求。     

茶叶中有机磷农药残留量的GC-MS测定

利用GC-MS在选择离子模式下对茶叶中几种有机磷农药进行定性和定量分析，在提取过程中，省去过柱操作步骤，缩短了操作时间。结果表明，5种有机磷农药的添加质量浓度为1．0mg／kg时，回收率均在86．5％～101．5％，RSD在4．8％～9．0％之间，方法的检出限在0．0047～0．023mg／kg，符合农药残留量检测要求。     

对甲苯胺衍生高效液相色谱法测定夏桑菊中熊果酸的含量

建立了柱前衍生高效液相色谱紫外可见检测夏桑菊中熊果酸的分析方法。在CSz介质中用对甲苯胺衍生熊果酸,于C18柱上,以pH=6．2的甲醇-水(80：20,V／V)为流动相,290nm检测衍生物,熊果酸在0．3～30．0mg／L范围内与色谱峰高呈良好线性关系,r=0．9986,检出限为2．46μg／L。平均回收率为101．2％(n=5),相时标准偏差为2．5％。方法易行,可用于该制剂的质量控制。     

使用限进介质色谱柱的柱切换高效液相色谱法直接进样测定大鼠血浆中舒必利

提出一种直接进样测定大鼠血浆中舒必利浓度的高效液相色谱方法,使用限进介质色谱柱作为预柱在线去除血浆蛋白后,将舒必利通过柱切换转移到分析柱中进行分析。限进介质色谱柱为CAPCELLPAKMFSCX阳离子交换柱（20×4．0mmi．d．,5μm）,分析柱为Kromasil C18柱（150×4．6mm i．d．,5μm）,限进介质柱预分离时流动相为PH=6．88的50mmol／L磷酸盐缓冲液乙腈（100：5,V／V）,切换后分析流动相为PH=6．83的50mmol／L磷酸盐缓冲液-乙腈（100：10,V／V）。流速均为1mL／min,检测波长为240nm。该方法检出限为17ng／mL,定量限为50ng／mL。舒必利在50～1400ng／mL之间线性良好（r=0．9997）,高中低浓度的日内、日间相对标准偏差分别为1．5％～4．2％及2．0％～5．2％,方法回收率为98．8％～104．1％．     

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。     

基质固相分散-加速溶剂萃取-气相色谱法测土壤中有机氯农药残留

建立了用弗罗里硅土作基质固相分散剂的加速溶剂萃取、并以灭蚁灵（Mirex）为内标的快速、同时测定土壤中16种有机氯农药的气相色谱法。加速溶剂萃取仪在100℃,10．3Mpa用正己烷和丙酮（1：1,V／V）静态提取样品10min,0．01μg/g加标水平回收率为77．3％-101．3％;方法检出限为0．01—0．04ng／g。方法满足了土壤中有机氯农药残留测定的要求。对我国南方不同地域的72个土壤样品进行了测定,大部分有机氯农药在土壤中都有一定检出量,其中环氧七氯最高（2．6～844．5ng／g）,甲氧DDT（23．2—219．8ng／g）和P,P’-DDT（4．0—183．1ng／g）次之,而o,P＇-DDT在72个土样中都没有检出。     

反胶束萃取-高效液相色谱法测定磺酸型偶氮染料

建立了水中磺酸偶氮染料甲基橙（MO）、刚果红（CR）和酸性铬兰K（ACBK）的反胶束萃取-离子对高效液相色谱定量检测的方法。采用Hypersil C18柱（250×4．6mm,5μm）,流动相为V（甲醇）／V（水）=63：37（含10mmol／L的KH2PO4、4mmol／L的四丁基溴化铵,KOH调pH=7．0）,流速为0.8mL／min,MO、CR和ACBK检测波长分别为449nm、505nm和526nm。结果表明,染料的回收率为92．9％～102．1％,相对标准偏差为0．9％～2．3％,水中MO、CR和ACBK的检出限分别为0．6μg／L、1．2μg／L和1．3μg／L。     

反相高效液相色谱法测定人血浆中利培酮及其代谢物的质量浓度

 建立了测定人血浆中利培酮及其活性代谢物9-羟利培酮质量浓度的反相高效液相色谱方法。用Zor－baxODSC18色谱柱,以V（甲醇）：V（水）：V（1mol／L醋酸铵）：V（3mol／L氨水）＝300：50：3：1为流动相,检测波长为280nm,流速为0．8mL／min。利培酮的线性范围为2～600μg／L（r＝0．996）,回收率为（98．2±3．5）％,日内与日间的标准偏差分别为4．12％和4．83％;9-羟利培酮的线性范围为2～800μg／L（r＝0．998）,回收率为（97．8±3．8）％,日内与日间的标准偏差分别为4．28％和4．81％。     

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.     

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.