荧光法测定环境水中微量久效磷

采用荧光分光光度法测定了环境水中微量久效磷的含量。在0.25％的吲哚丙酮溶液与0.25％的过硼酸钠溶液的混合液中,体系温度为5℃时,λ_x/λ_m=420 nm/500 nm。检测限为4.0μg/L,线性范围为0～3.2μg/mL,回收率为98％～104％,结果令人满意。     

顶空气相色谱法测定合成盐酸伪麻黄碱中的甲醇残留量

选用HP-5型毛细管柱(30m×0.53 mm i. d., 1.5μm)和氢火焰离子化检测器,用顶空气相色谱法测定合成盐酸伪麻黄碱中的甲醇残留量。该方法的线性范围为0～11.7μg/mL,线性回归方程为Y=0.204c+0.111,相关系数r=0.9997,检出限为0.4 μg/mL,相对标准偏差为0.8％～1.4％,回收率为97.8％～104.2％。该方法操作简单,测定结果准确。     

硫氰酸汞分光光度法测定空气颗粒物中的氯化氢

用硫氰酸汞分光光度法分别测定空气及空气颗粒物和空气中氯化氢的含量,利用相减法得出空气颗粒物中氯化氢的含量。线性范围为0～1．00μg/mL,线性回归方程为A=0．0799c 0．00124,相关系数为0.9995。该方法灵敏、简便,测定结果的相对标准偏差为6．8％(n=7),加标回收率为98．1％～103．9％。     

HPLC-AFS联用测定海产品中砷的形态

建立了高效液相色谱-原子荧光分光光度法测定海产品中无机砷(As V,AsⅢ)、有机砷(DMA,MMA,AsB)含量的方法.样品经含10％(体积分数)HC1的提取液振荡提取、离心分离、二路形态分析预处理、高效液相色谱分离,用原子荧光光度计检测As(Ⅲ),DMA,MMA,As(v);四路条件(过氧化氢氧化和开启紫外灯)形态分析预处理装置处理,高效液相色谱分离,原子荧光光度计测定AsB.As(Ⅲ)线性范围为0～100.00 μg/L,r2=0.9997;DMA线性范围为0～100.00 μg/L,r2=0.9993;MMA线性范围为0～100.00 μg/L,r2=0.9990;As(Ⅴ)线性范围为0～100.00 μg/L,r2=0.999 1;AsB线性范围为0～200.00 μg/L,,r2=0.9994.3个样品加标回收率为As(Ⅲ)86.7％～89.4％,DMA 111.2％～117.0％,MMA 109.7％～111.6％,As(Ⅴ) 83.8％～90.7％,AsB 88.3％～90.4％.用该方法测定虾仁(干)5个价态测定结果的相对标准偏差为3.07％～9.93％(n=6).5个价态的检出限(S/N=2)为As(Ⅲ)0.29 μg/L,DMA 0.36 μg/L,MMA 0.27 μg/L,As(V) 0.56 μg/L,AsB l.46 μg/L.该方法适用于海产品中As(Ⅲ),DMA,MMA,As(V),AsB含量的测定.     

石墨炉原子吸收分光光度法测定大气颗粒物中的镍

用有机滤膜或有机滤筒采集大气颗粒物样品,以硝酸、高氯酸消解处理,用石墨炉原于吸收分光光度法测定大气颗粒物中的镍含量。方法的线性范围为0～0.50μg/L,线性回归方程为A=0.892c+0.0148,相关系数r=0.9994,相对标准偏差为3.9％～7.8％,回收率为90％～94％,检出限为7.00×10~(-3)μg/L。该方法的各项指标均符合环境监测的质控要求,适用于大气和固定污染源排气颗粒物中镍的测定。     

顺序注射蒸气发生非色散原子荧光光谱法测定环境样品中痕量硒

建立了双泵顺序注射与氢化物发生非色散原子荧光光谱法联用,测定环境样品中痕量硒的方法。线性范围为0．25～10μg/L;检出限为0．02μg／L;测定精度(RsD)为0．97％(2μg／L,n=11)。每小时可分析80(240次注射)个样品。环境水样的回收率为97％～107％;对国家标准参考物质(GBW07405和GBW07314)的测定结果同推荐值一致。     

火焰原子吸收法测定苹果汁中的钠

用浓硝酸及高氯酸消化苹果汁样品，以氯化钾作为电离缓冲剂，建立了测定苹果汁中钠的火焰原子吸收法。方法的线性范围为0～0．6μg／mL，线性回归方程为A=1．0182c 0．0462，相关系数r=0．9971，检出限为0.9μg／L。测定浓缩苹果汁、苹果原汁中钠的相对标准偏差分别为0．6％、1．3％，加标回收率分别为99.0％～lOl.3％、98．0％～103．2％。     

石墨炉原子吸收分光光度法测定空气中的铍

对300余个样品进行监测,选择灵敏度高的石墨管和最佳基体,提高灰化、原子化的温度,确立了石墨炉原子吸收法测定空气中铍含量的实验条件。样品采用干灰化消解法,最佳溶剂为质量分数l％的硝酸溶液,利用仪器内置的样品浓度计算程序,绘制工作曲线直接获得样品中铍的含量。方法检出限为0．021μg／L,测定结果的相对标准偏差小于2％（n=6）,线性范围为0～6．5μg／L,加标回收率为91．6％～107％。     

火焰原子吸收光谱法测定预混合饲料及浓缩饲料中的高含量锰

以锰280．1nm次灵敏线作为分析谱线，用原子吸收光谱法测定预混合饲料和浓缩饲料中的高含量锰。锰的线性范围为0～12μg／mL，相关系数r=0．9994，相对标准偏差小于l％，回收率为97％～102％。该方法的测定结果与常规灵敏线原子吸收光谱法的测定结果基本一致。     

高压釜消解-氢化物发生原子荧光光度法测定土壤中的砷、硒

对高压釜密封消解一氢化物发生原子荧光法测定土壤中砷、硒的方法进行了研究。采用HNO3-HClO4作消解剂，在最佳的消解条件和测定条件下，测定砷、硒的线性回归方程分别为I=244．1c 1．03、I=88．26c 2．86．线性范围均为0．50～10．00μg／L，相关系数均为0．9999，检出限均为0．0002μg/mL。测定土壤中砷、硒的回收率分别为90％～105％、89％～104％，RSD分别为2．2％～4．0％、1．9％～3．1％。     

二氧化碳和丙烯直接合成甲基丙烯酸的NiPMo/TiO2催化剂的研究

用溶胶-凝胶法以磷钼酸(MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2催化剂.使用ICP、 XRD、 TG-DTA、 IR、 TPD-MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能.杂多钼酸盐与TiO2通过O2-在TiO2表面发生了键合.在623 K下,杂多阴离子仍保持原有的Keggin结构.CO2在Lewis酸位Ni(Ⅱ)和Lewis碱位Ni-O-Mo的桥氧协同作用下生成CO2卧式吸附态Ni(Ⅱ)←O-(CO)←(O--Ni).丙烯有多种吸附态在催化剂上吸附.在563 K、 1 MPa和空速1500 h-1的反应条件下,丙烯的摩尔转化率为3.2%,产物MAA选择性为95%.     

Synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives

Different approaches for the synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives from simple amino acids have been investigated. A library of 33 precursors for the preparation of N-hydroxy pyrazinones was obtained in moderate to good yields.     

A general and convenient synthesis of 4-(tosylmethyl)semicarbazones and their use in amidoalkylation of hydrogen,heteroatom, and carbon nucleophiles

A general synthesis of previously unknown semicarbazone-based α-amidoalkylating reagents, 4-(tosylmethyl)semicarbazones, has been developed. The synthesis involved three-component condensation of semicarbazones of aliphatic or aromatic aldehydes with the same or other aldehydes and p-toluenesulfinic acid. The scope and limitations of this reaction were investigated. The compounds obtained were demonstrated to be an efficient α-(4-semicarbazono)alkylating agents. They were reacted with H- (sodium borohydride), O- (sodium methylate), S- (sodium phenylthiolate), N- (pyrrolidine, sodium succinimide), P- (trialkyl phosphites), and C-nucleophiles (sodium diethyl malonate) to give the corresponding products of the tosyl group substitution, 4-substituted semicarbazones, including analogues of nitrofurazone. Among the prepared compounds tested in vitro for antibacterial and antifungal activity, three nitrofuryl-containing semicarbazones exhibited high biological activities with minimum inhibitory concentration (MIC) values of 8–32 μg/mL.     

Toward new camptothecins. Part 6: Synthesis of crucial ketones and their use in Friedländer reaction

In the context of the preparation of camptothecin and luotonin A analogs, the synthesis of some key keto-precursors and their use in Friedländer condensation are described. This paper also focuses on the stability of these keto intermediates and emphasizes the major differences between indolizinones and pyrroloquinazolinones series. Noteworthy is also the report of some original structures isolated as by-products of some experiments.     

Synthesis of novel chiral bidentate hydroxyalkyl-N-heterocyclic carbene ligands and their application in palladium-catalyzed Mizoroki–Heck couplings and asymmetric addition of diethylzinc to benzaldehyde

A small library of new chiral bidentate hydroxyalkyl-imidazolium salts 1 is conveniently synthesized on multi-gram scale from inexpensive and commercially available chiral pool amino acids. The corresponding carbenes, generated by deprotonation of imidazolium salts 1, in combination with palladium(II) chloride were tested in the Mizoroki–Heck coupling reaction. The most significant results in terms of yields and reactivities were achieved with low catalyst loading. The catalytic activities of these imidazolium salts were also investigated in the asymmetric addition of diethylzinc to benzaldehyde. The use of MgO nanoparticles as an additive in conjunction with these ligands played a crucial role in increasing the efficiency of these reactions.     

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.     

CoFe2O4自形成磁性液体场致结构化对磁化的影响

The Langevin paramagnetic theory can’t describe the relation between magnetization of ferrofluids and applied magnetic field. The structuralization of ferrofluids, which is considered the main influence factor of the magnetization, is regarded. The part of magnetization works is deposited when the structure is forming. This action influences the magnetization of ferrofluids directly or indirectly. On the base of the “compressing” model, the Langevin function that usually describes the magnetization of ferrofluid is modified, and a well-fitted curve is obtained. An equation of the relation between the equivalent volume fraction after being “compressed” and the intensity of magnetic field is discovered, which approximately describes the process of magnetization. The relation between the approximate initial susceptibility and the volume fraction can be obtained from modified formula.     

Microwave-assisted copper-catalyzed stereoselective ring expansion of three-membered heterocycles with α-diazo-β-dicarbonyl compounds

Microwave-assisted copper-catalyzed ring expansions of three-membered heterocycles with α-diazo-β-dicarbonyl compounds were investigated. Thiiranes generated 3-acyl-5,6-dihydro-1,4-oxathiines in the presence of copper sulfate and trans-3-acyl-5,6-dihydro-1,4-oxathiines as stereospecific products for 1,2-disubstituted cis-thiiranes through an intramolecular S_N2 process. Oxiranes gave rise to 2-acyl-5,6-dihydro-1,4-dioxines under the catalysis of copper hexafluoroacetylacetonate and cis-3-acyl-5,6-dihydro-1,4-dioxines as stereospecific products for 1,2-disubstituted cis-oxiranes via an intimate ion-pair mechanism. The current method provides a direct and simple strategy in efficient preparation of 3-acyl-5,6-dihydro-1,4-oxathiines and 2-acyl-5,6-dihydro-1,4-dioxines, important agents in medicinal and agricultural chemistry, from readily available thiiranes and oxiranes, respectively.     

KMnO4-mediated oxidative CN bond cleavage of tertiary amines: Synthesis of amides and sulfonamides

KMnO₄-mediated oxidative CN bond cleavage of tertiary amines producing secondary amine was introduced, which was trapped by electrophiles (acyl chloride and sulfonyl chloride) to form amides and sulfonamides. The reaction could take place at mild condition, tolerating a wide range of function groups and affording products in moderate to excellent yields.