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）。     

多功能针式过滤器净化超高效液相色谱法测定大米和花生中玉米赤霉烯酮

建立了一种基于多功能针式过滤器净化的超高效液相色谱测定大米和花生中玉米赤霉烯酮的方法。样品经乙腈提取,采用多功能针式过滤器通过式净化,以超高效液相色谱法测定其中的玉米赤霉烯酮,色谱柱为ACQUITY UPLC BEH C18柱（100 mm×2.1 mm,1.7μm）,以甲醇-乙腈-水（体积比为8∶46∶46）为流动相等度洗脱,流量为0.3 mL/min,用荧光检测器检测,色谱峰面积外标法定量。玉米赤霉烯酮的质量浓度在2.5～500 ng/mL范围内与色谱峰面积线性关系良好,相关系数不小于0.999 5。大米和花生样品的方法检出限分别为15.0、30.0μg/kg,定量限分别为50.0、100.0μg/kg。样品加标回收率为77.11%～93.65%,测定结果的相对标准偏差为0.49%～4.95%(n=6)。该方法简便快速,适用于大米和花生中玉米赤霉烯酮的日常检测。     

粮食中玉米赤霉烯酮和镰刀菌氧萘满酮高效液相色谱分析方法的研究

建立了粮食样品中镰刀菌氧萘满酮（ＴＤＰ－１）和玉米赤霉烯酮（ＺＥＡ）的高效液相色谱－荧光检测分析方法。粮食样品在碱性和中性条件下用乙腈－水（３：１,Ｖ／Ｖ）提取,经正己烷脱脂,过Ｆｌｏｒｉｓｉｌ柱净化,最后用反相高效液相色谱－荧光检测法测定。该法的最低检出灵敏度：玉米赤霉烯酮为５×１０＾－９ｇ,镰刀菌氧萘满酮为１×１０＾－９ｇ。玉米中镰刀菌氧萘满酮和玉米赤霉烯酮的回收率分别为１００．２％和９２．４     

麦类中玉米赤霉烯酮的快速检测

提出了高效液相色谱荧光检测法测定麦类样品中玉米赤霉烯酮的方法.样品经乙腈-水(84 16,体积比)提取,多功能柱净化,C18色谱柱(4.6 mm×250 mm,5um)分离,水-乙腈-甲醇(46 46 8,体积比)混合溶液作流动相,流速1.0 mL·min-1.玉米赤霉烯酮的质量浓度在20.0～5 000 ug·L-1范围内,峰面积与玉米赤霉烯酮浓度之间呈线性关系,样品在50.0,100.0,1 000.0 ng·g-1添加水平的平均回收率分别为74.6%,75.5%,73.5%,相对标准偏差为9.7%～11.5%(n=8)之间,方法的测定限(10S/N)为50.0 ng·g-1.     

液相色谱-串联质谱法测定饲料中14种霉菌毒素及其类似物

采用高效液相色谱-电喷雾串联质谱仪(LC-ESI-MS-MS),在多反应监测(MRM)模式下建立了饲料中玉米赤霉烯酮、黄曲霉毒素和单端孢霉烯族A类毒素等14种毒素及其类似物的快速确认测定方法。试样中的黄曲霉毒素、玉米赤霉烯酮和单端孢霉烯族A类毒素经乙腈-水(84:16,V/V)提取,正己烷脱脂及霉菌毒素多功能净化柱净化,氮气吹干,用1mL乙腈/水(1:1,V/V)定容后,进行液相色谱-串联质谱法测定,采用色谱保留时间和质谱碎片离子丰度比定性,外标法定量。采用正离子扫描和负离子扫描的方式进行仪器方法学研究,确定丰度比最高的2对离子作为监测离子,进行MRM模式定性定量分析。本方法的检出限(LOD)为0.1～0.8μg/kg;线性范围为2.0～200.0μg/L,相关系数r均大于0.999。在5.0～100μg/kg的添加水平上,上述14种霉菌毒素及其类似物的平均回收率为59.0%～107%;相对标准偏差为2.1%～12.6%。     

免疫亲和柱净化-柱后光化学衍生-高效液相色谱法同时检测粮谷中的黄曲霉素、玉米赤霉烯酮和赭曲霉毒素A

建立了同时检测粮谷中黄曲霉毒素(B1、B2、G1和G2)、玉米赤霉烯酮和赭曲霉毒素A的免疫亲和柱净化-柱后光化学衍生-高效液相色谱方法.样品经过甲醇-水(体积比为80∶20)提取,通过免疫亲和柱富集和净化,采用Waters Nova-Pak色谱柱(3.9 mm I.d.×150 mm,4 μm),以甲醇、乙腈和1%的磷酸溶液为流动相,梯度洗脱,柱后光化学衍生、改变波长荧光检测.黄曲霉毒素(B1、B2、G1和G2)、玉米赤霉烯酮和赭曲霉毒素A检出限分别为0.24,4.0和0.5 μg/kg,标准曲线的线性范围分别为0.24～6.0,4.0～100.0和0.5～40.0 μg/L;在小麦、玉米、黑麦样品中,平均加标回收率为70.8% ～94.0%,相对标准偏差为2.79% ～9.38%.     

免疫亲和柱净化-高效液相色谱法同时检测鸡蛋中6种玉米赤霉醇类化合物残留量

建立了鸡蛋中6种玉米赤霉醇类化合物(α-玉米赤霉醇、β-玉米赤霉醇、α-玉米赤霉烯醇、β-玉米赤霉烯醇、玉米赤霉酮和玉米赤霉烯酮)残留量的免疫亲和柱净化-高效液相色谱检测方法。样品酶解后用叔丁基甲醚提取、氢氧化钠反萃取,经免疫亲和柱富集和净化后,采用高效液相色谱-紫外检测器进行测定。色谱柱: Agilent Eclipse XDB-C18(150 mm×4.6 mm, 3.5 μm);流动相: 甲醇-乙腈-水(50:15:35, v/v/v);流速: 1.0 mL/min;检测波长: 270 nm。结果表明,6种目标物在0.01～0.2 mg/L范围内线性关系良好,相关系数(r)≥0.9998,检出限(LOD,S/N≥3)为1.0 μg/kg,平均回收率为73.2%～95.7%,相对标准偏差小于8%。该方法灵敏度高、重现性好,适用于鸡蛋样品中痕量玉米赤霉醇类药物残留的测定。     

多功能柱净化-柱后光化学衍生-高效液相色谱法同时检测玉米和花生中9种真菌毒素

建立了同时检测玉米和花生中黄曲霉毒素B1、B2、G1、G2、M1、M2、玉米赤霉烯酮、呕吐毒素和展青霉素的多功能柱净化-柱后光化学衍生-高效液相色谱检测方法。样品经乙腈-水(体积比为86∶14)提取,多功能净化柱净化,采用C18柱分离,以甲醇、乙腈和水为流动相进行梯度洗脱,在线光化学衍生,以荧光和二极管阵列测器同时检测。黄曲霉毒素B1、B2、G1、G2、M1、M2、玉米赤霉烯酮、呕吐毒素和展青霉素的检出限分别为0.02μg/kg、0.01μg/kg、0.03μg/kg、0.05μg/kg、0.08μg/kg、0.04μg/kg、0.09μg/kg、0.20mg/kg和0.04 mg/kg,在相应浓度范围内线性相关系数均大于0.999,平均加标回收率为80.0%~101.5%,相对标准偏差在1.3%~5.6%之间。该方法简便快速、灵敏度高、重现性好,可满足玉米、花生中9种黄曲霉毒素的检测。     

谷物中脱氧雪腐镰刀菌烯醇的高效液相色谱检测及质谱确证

建立了谷物中脱氧雪腐镰刀菌烯醇DON的高效液相色谱检测和质谱确证方法。样品用水提取,通过免疫亲和柱进行富集和净化,以Hypersil BDS C18柱为分离柱,乙腈-水（10：90,V/V）混合溶剂为流动相进行高效液相色谱分离和检测,利用大气压化学电离质谱（APCI）进行阻性结果的鉴定和确认。在小麦、大麦和面粉等样品中,本方法在0．1～10μg／g添加范围内的回收率为82．4％-103％,相对标准偏差1．4％-7．6％,检出限0．1μg／g。     

固相萃取-超高效液相色谱-串联质谱法检测粮食及其制品中的玉米赤霉烯酮类真菌毒素

建立了粮食及其制品中6种玉米赤霉烯酮类物质(α-玉米赤霉醇、β-玉米赤霉醇、α-玉米赤霉烯醇、β-玉米赤霉烯醇、玉米赤霉酮和玉米赤霉烯酮)的超高效液相色谱-串联质谱(UPLC-MS/MS)检测方法。样品用84%(体积分数)乙腈水溶液提取,通过ENVI-Carb石墨化炭黑(GCB)固相萃取柱进行富集净化,用6 mL二氯甲烷-甲醇(7:3, v/v)溶液洗脱,采用UPLC-MS/MS进行测定。在ACQUITY UPLCTM BEH C18反相柱上分离,梯度洗脱,流动相为水和乙腈;质谱采集模式为电喷雾负离子多反应监测模式。以α-玉米赤霉烯酮-d4为内标,6种目标物的线性范围为0.1～50 μg/L,相关系数(R2)大于0.99,检出限为0.1～0.2 μg/kg, 3个不同水平的加标平均回收率为79.9%～104.0%,相对标准偏差不大于10%。应用该方法对北京市的粮食及相关产品进行了分析,结果发现玉米赤霉烯酮的检出率最高,含量为0.42～220.7 μg/kg;此外还检出了α-和β-玉米赤霉烯醇。该方法具有操作简单、灵敏度高、重现性好等特点,符合食品样品中痕量污染物的检测要求。     

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.