饲料中盐酸克伦特罗、沙丁胺醇高效液相色谱测定

建立了用液相色谱法同时测定饲料中违禁药物盐酸克伦特罗、沙丁胺醇含量的方法 ;样品经甲醇 -盐酸溶液提取后 ,经液 -液萃取、固相萃取小柱净化 ,用ZorbaxCN柱分离 ,二极管阵列检测器检测、外标法定量 ;盐酸克伦特罗、沙丁胺醇的定量下限(w)分别为0.10×10-6 、0.36×10-6,回收率分别大于88 %和74 % ,RSD(n=5)分别小于6.4 %和3.0%。     

Fe(Ⅲ)-8-羟基喹啉极谱络合吸附波的研究

以8-羟基喹啉作为络合剂,用单扫描极谱仪对微量Fe(Ⅲ)的络合吸附波进行了研究。8-羟基喹啉用量为2×10~(-3)mol/L时,用氢氧化钾溶液调节pH值至碱性条件(pH约为12.0),于-0.37V(vs. SCE)处,有一灵敏的阴极波。Fe(Ⅲ)浓度在2.1×10~(-8)～2.6×10~(-6)mol/L范围内与一阶导数波峰高成线性关系。该法可用于准确测定样品中痕量Fe(Ⅲ)。     

棉花植株及土壤中丙硫克百威及其代谢物残留气相色谱测定

研究超声波提取、毛细管气相色谱配氮磷检测器(NPD)检测棉花植株及土壤中丙硫克百威及其代谢物残留 ,各组分回收率83%～110 % ,线性范围0.1～100mg/L,最低检测质量分数0.01×10-6～0.02×10-6(w) ;该法具有简单、快速、节省试剂的特点     

利用粉末微电极检测谷胱甘肽及L-半胱氨酸

本文研究了谷胱甘肽 ( GSH)和 L-半胱氨酸 ( L- cys)在碳粉末微电极上的电化学行为 ,并分别用乙炔黑粉末和 Ketjenblack粉末填充的微电极检测了溶液中GSH和 L- cys的浓度。 GSH和 L- cys在粉末微电极上的检出限分别为 3.4× 1 0 - 6mol/ L和 2 .5× 1 0 - 6 mol/ L,线性范围分别为 3.6× 1 0 - 5～ 4.5× 1 0 - 3mol/ L和 1 .5×1 0 - 5～ 5 .0× 1 0 - 3mol/ L。采用粉末微电极技术完全避免了尿酸和对 -乙酰氨基苯酚对测量谷胱甘肽的干扰 ;0 .0 6mmol/ L的抗坏血酸引起的干扰约为 8%。     

几种动物源性食品中氯霉素残留量的气相色谱双电子俘获检测

研究了几种动物源性食品中氯霉素残留量的气相色谱测定方法;样品中氯霉素残留用乙酸乙酯提取,浓缩至干,溶于氯化钠溶液,用正己烷脱脂,水层再用乙酸乙酯提取,浓缩后用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,用外标法定量;采用不同极性的色谱柱定性。当添加水平为0.3×10-9～10×10-9(w)时,回收率大于80%,相对标准偏差小于20%,线性相关系数r＝0.999。     

Ru（bipy）3^2＋—CO3^2——SO3^2——KClO3体系化学发光法测定空气中的二氧化硫

提出了Ru(bipy) 2+ 3-CO 2- 3-SO 2- 3-KClO 3体系化学发光法测定溶液中亚硫酸盐的方法.SO 2- 3浓度与化学发光强度在1.0×10-7～1.0×10-4 mol/L 范围内成正比,检出限为8.76×10-8 mol/L,对1.0×10-4 mol/L SO2-3溶液6次测定的相对标准偏差为2.9%.该法用三乙醇胺作为吸收液,成功地用于测定空气中二氧化硫的含量,结果满意.     

纳米石墨烯修饰电极电化学发光法测定盐酸氯丙嗪的研究

基于盐酸氯丙嗪对联吡啶钌电化学发光的增敏作用,以石墨烯(Graphene)和Nafion复合膜修饰的玻碳电极(GCE)为工作电极,建立了一种直接测定盐酸氯丙嗪的电化学发光新方法。最佳实验条件下,盐酸氯丙嗪浓度在8.0×10-7 ~1.2×10-4 mol/L范围内与其相对发光强度呈良好线性关系(r=0.998 8),且在该修饰电极上的检出限(S/N=3)为4.0×10-7 mol/L。连续测定4.0×10-6 mol/L盐酸氯丙嗪溶液11次,发光强度值的相对标准偏差(RSD)为1.4%,表明该修饰电极具有较好的重复性和灵敏度。盐酸氯丙嗪的加标回收率为93%~104%,RSD(n=5)为4.1%。将该方法应用于药片中盐酸氯丙嗪的检测,结果满意。     

一种评价离子选择性电极综合性能的新方法及其在盐酸强力霉素PVC膜选择性电极研制中的应用

以电极的响应斜率、响应线性、检出限和响应时间等参数 ,首次提出了一个评价离子选择性PVC膜电极综合性能的新方法———综合性能指数 (ICQ) ,应用ICQ 于以盐酸强力霉素 -四苯硼酸根为电活性物 ,以邻苯二甲酸二丁酯为增塑剂的盐酸强力霉素离子选择性电极的PVC膜成分优选 ;该电极在5.0×10-6～3.2×10-2mol/L范围内呈线性响应 ,斜率为54.5mV/pc,检出限为2.4×10 -6mol/L ;采用直接电位法测定药物片剂中的盐酸强力霉素的含量 ,方法的回收率为99.6%～100.1% ;研究发现 ,当溶液 pH>4时以盐酸强力霉素 -磷钨酸根离子缔合物为电活性物的盐酸强力霉素PVC膜电极呈现超_Nernst响应     

溶出伏安法同时测定水中痕量铀和镍

本文报道了同时测定钴和镍的一种方法.在 0.01mol/L NH_3·H_2O-0.01mol/LNH_4Cl-3.0×10~(-5)mol/L安息香缩氨基硫脲(BTSC)溶液中,钴(Ⅱ)和镍(Ⅱ)均产生非常灵敏的还原波,其峰电位分别是:-0.94和-0.75V(vs.SCE),峰电流与钴和镍的浓度分别在2.0×10~(-8)~1.0×10~(-6)和1.0×10~(-8)~8.0×10~(-7)mol/L范围内成直线关系,该方法用于测定水中痕量钴和镍,相对标准偏差分别为1.4~2.0%和2.1~2.5%,回收率分别在98.0%~101.8%和97.9%~102.1%之间.     

流动注射胶束电化学发光测定过氧化氢的研究

建立了一种简易、快速检测过氧化氢的流动注射电化学发光法。本法基于铂丝阳极在 1.3 V(vs.Ag Cl/Ag)时 ,在含有 Na2 CO3 -Na HCO3 缓冲溶液的 KCl支持电解质中现场产生试剂 ,当注入过氧化氢溶液后即产生电化学发光。加入 Triton X-10 0形成的胶束能增强这一体系的发光强度。该法测定过氧化氢的线性范围为 1.0×10 -7～ 1.0× 10 -5 mol/L,对 4.0× 10 -7mol/L的过氧化氢进行 11次测定的相对标准偏差为 2 .6%。用这一方法对雨水中的过氧化氢进行了测定 ,结果满意。     

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.     

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.     

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.     

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%).     

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.     

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.     

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.     

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.