近海贻贝、牡蛎中有机氯农药和多氯联苯的气相色谱法测定

应用毛细管柱气相色谱技术对大连近海的贻贝、牡蛎体中的有机氯农药和多氯联苯进行了分析研究;贻贝、牡蛎样品中有机氯和多氯联苯经超声提取、柱色谱分离后 ,由GC -ECD测定 ,检出了8种有机氯农药(α_666、β_666、γ_666、δ_666、o,p′_DDE、p,p′_DDE、p,p′_DDD、p,p′_DDT)和10种多氯联苯(PCB28、PCB52、PCB155、PCB101、PCB112、PCB118、PCB153、PCB138、PCB180、PCB198);有机氯农药含量分布在0.16×10-9～37.9×10-9(w)之间 ,回收率为77 %～89% ;多氯联苯含量分布在0.03×10-9～28.9×10-9(w)之间 ,回收率为75 %～101%。     

气相色谱-负化学源质谱法测定蜂蜜和奶粉中氯霉素残留量

研究了蜂蜜和奶粉中氯霉素残留量的气相色谱——质谱分析方法。将样品溶于水，其中的氯霉素残留物用乙酸乙酯提取，提取物用C18固相萃取柱净化，净化液再用乙酸乙酯反提取，经N，O-双(三甲基硅烷基)三氟乙酰胺(BSTFA) 1％三甲基氯硅烷(TMCS)衍生后，用配有负化学源质谱检测器的气相色谱仪测定。当添加水平为0．1～10μg/kg时，回收率为80．4％～95．3％，相对标准偏差为9．3％～18．1％。     

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。     

两种离子源技术GC/MS法检测蔬菜中多类除草剂的残留量

采用电子轰击(EI)和负化学(NCI)离子源两种离子源技术气相色谱-质谱联用法(GC-MS)测定了蔬菜中10类除草剂的残留量, 并对两种方法进行了比较. 样品经乙腈提取后, 用PSA固相萃取柱净化, 由气相色谱-质谱联用EI或NCI技术进行定量和定性分析. 对含电负性强的除草剂分析, NCI灵敏度高, 在10 ng/g, 20 ng/g和40 ng/g 3个添加水平下的方法回收率为70%～115%, RSD为1.7%～10.1%, 两种离子源技术可以互相补充用于准确检测蔬菜中多类除草剂.     

分散固相萃取/气相色谱质谱法测定动物源性食品中的氟虫腈及其代谢物

采用电子轰击(EI)和负化学(NCI)两种离子源技术建立了气相色谱-质谱联用法(GC-MS)和气相色谱-三重四极杆串联质谱法(GC-MS/MS)测定肉、蛋及内脏中氟虫腈及其代谢物残留的分析方法,并对3种方法进行了比较。样品经乙腈提取,PSA、C18和GCB净化后,由气相色谱-质谱联用EI或NCI技术及GC-MS/MS在多反应离子监测(MRM)模式下进行测定,外标法定量。结果表明,3种方法下氟虫腈及其代谢物在0.001~2.0 mg/L范围内均呈良好的线性关系,相关系数(r2)均大于0.999 0,GC-MS/EI、GC-MS/NCI以及GC-MS/MS/EI的检出限(LOD)分别为0.15、0.05、0.15μg/kg,定量下限(LOQ)分别为0.5、0.2、0.5μg/kg。对电负性强的氟虫腈及其代谢物进行分析,GC-MS/NCI的灵敏度高,在2、50、500μg/kg 3个加标水平下的方法回收率为80.0%~108.0%,相对标准偏差(RSD)为1.1%~7.6%。3种方法可互相补充用于动物源性食品中氟虫腈及其代谢物的检测和确证。     

气相色谱-负化学电离质谱测定蔬菜中啶虫丙醚的残留量

建立以固相萃取净化和气相色谱-负化学质谱(GC/NCI/MS)技术快速测定蔬菜中啶虫丙醚残留量的方法。经乙腈提取,共提物中的基体杂质经PSA/SAX固相萃取柱去除,用负化学源质谱检测,灵敏度选择性高于气相色谱-电子轰击源质谱。目标农药的平均回收率为87.0%～91.0%,平均相对标准偏差为6.45%～6.80%(n=7),方法的检出限为1μg/kg。     

离子阱串联质谱法检测鱼肉中指示性多氯联苯

建立了使用离子阱串联质谱技术和同位素稀释技术准确测定鱼肉中的7种指示性多氯联苯（PCB）单体的方法。方法的检出限为0．025—0．068ng／g,6个加标鱼样（添加水平1ng／g）中7个单体的回收率为87.2％～103.7％,RSD为3．2％-8．7％（n=6）。本方法定量准确可靠,可用于食品中指示性PCB的测定。     

高效液相色谱-串联质谱法测定动物源性食品中硝基呋喃类代谢物残留量

依次用甲醇、乙醇和乙醚溶剂提取，使动物源性样品中呋喃唑酮、呋喃西林、呋喃它酮、呋喃妥因等4种硝基呋喃类游离态代谢物进入提取液，而结合态代谢物保留在残渣中。在酸性条件下用2-硝基苯甲醛分别衍生游离态和结合态代谢物，经乙酸乙酯提取浓缩后，用液相色谱-四极杆串联质谱仪定性，用同位素内标法定量。检出限均为0．3μg/kg。在0．3、1．0和5．0μg/kg3个浓度水平上进行加标回收试验，回收率为85．2％～112．5％，相对标准偏差均不大于6．3％(n=6)。     

气相色谱-负化学电离源质谱法测定鱼油中16种多氯联苯

建立了气相色谱-负化学电离源质谱(GC-NCI-MS)同时测定鱼油中16种多氯联苯(PCBs)的方法。鱼油样品经正己烷提取和浓硫酸净化,在选择离子监测模式下进行GC-NCI-MS检测。所检测的PCBs在0.01~10 μg/L范围内呈现良好的线性关系(r>0.99),定量限(S/N=10)在3~67 pg/g之间。基质加标回收率为62.3%~121.8%,相对标准偏差(n=3)≤12%。相比传统的多种填料固相萃取前处理法,本方法样品处理简单快速,有机溶剂使用量少,具有较好的抗基质干扰能力和较高的灵敏度,适用于鱼油中痕量共平面多氯联苯及常见指示性多氯联苯等的同时检测。     

基质固相分散和GC-NCI-MS法分析果汁中拟除虫菊酯农药残留量

建立了基质固相分散法（MSPD）和气相色谱-负化学离子源-质谱法（GC—NCI—MS）应用于果汁中10种拟除虫菊酯农药残留量的快速分析方法，并对这些农药NCI—MS的阴离子结构与断裂机理进行初步探讨。采用以中性氧化铝为吸附刺、Florisil硅藻土为净化剂和乙酸乙酯为洗脱剂的MSPD样品前处理方法，以PCB103为内标物和GC—NCI—MS的选择离子监测方式（SIM）进行定性与定量分析。当样品的加标浓度水平为50、250μg／kg时，平均加标回收率为86．7％～114．8％，相对标准偏差为1.9％～14．1％；除氯菊酯农药的方法检出限（MDL）为14.7μg／kg外，其余农药的MDL大都小于1．0μg／kg；线性范围为10～500μg／kg，相关系数都大于0.997，在所分析的大部分果汁中至少分析出两种以上的拟除虫菊酯农药残留。     

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.