分子印迹功能介孔材料富集-火焰原子吸收光谱法测定溶液中痕量铅

以2-巯基苯骈噻唑为修饰剂,铅离子为印迹离子成功制备分子印迹功能介孔材料,并用扫描电镜(SEM)、傅里叶红外光谱对材料进行了结构表征。铅离子分子印迹功能介孔材料能很好地将Pb(II)与性质相近的二价重金属离子Cu(II),Cd(II)和Hg(II)分离,具有非常好的吸附选择性,且静态吸附容量0.64 mmol/g。利用该材料制备的分离富集柱可以很好地富集溶液中痕量铅离子,且仅用2 mL 0.5 mol/L EDTA以0.4 mL/min流速即可完全洗脱,富集倍数高达250倍。样品预富集后的火焰原子吸收光度法线性范围为0.5～1.2×104μg/L,r=0.999 2,检出限(3σ,n=11)为0.04μg/L。利用功能介孔材料分离富集水样中痕量铅离子,用火焰原子吸收法测定含量,相对标准偏差(RSD)小于等于3%(n=6),回收率在98.2%～99.1%之间。     

流动注射在线分离富集火焰原子吸收法测定环境样品中的铅和镉

使用PT-C18色谱预处理柱,以二乙基二硫代氨基甲酸钠（DDTC）和吡咯啶二硫代氨基甲酸铵（APDC）混合物为螯合剂,甲醇为洗脱剂,采用流动注射在线分离富集与原子吸收联且技术,对铅和镉的测定进行了研究。1min（4.2mL),检出限：Pb为6.90μg/L;Cd为0.45μg/L,相对标准偏差：Pb为2.80%;Cd为2.47%。     

流动注射微柱预富集-火焰原子吸收光谱法测定海水中铅(Ⅱ)

应用流动注射技术,用D412螯合树脂微柱富集海水中的铅(Ⅱ),并与火焰原子吸收光谱法相结合测定海水中铅(Ⅱ)。20mL海水样品以3mL.min-1流量进柱,被树脂螯合吸附富集,以0.2mol.L-1乙酸铵溶液5mL淋洗柱体去除干扰物,以4mol.L-1硝酸溶液4mL为洗脱剂(流量为7mL.min-1),洗脱液直接引入火焰原子吸收光谱仪雾化器,在线检测。当海水样进样20mL时,铅(Ⅱ)测定灵敏度可提高约35倍;检出限(3s)为1.3μg.L-1。实际应用于海水样品分析,加标回收率为94.5%,测定值的相对标准偏差(n=6)为2.2%。     

顺序注射-样品预处理模块系统-电热原子吸收法测定海水中痕量铜

将样品预处理模块与自动化顺序注射系统相结合,建立了未经稀释的海水中痕量铜的分离富集方法。铜-PDC螯合物在样品预处理模块中被吸附在聚四氟乙烯微珠填充柱上,用少量甲醇洗脱后,将洗脱液引入电热原子吸收中测定。进样体积为1.0mL时,富集倍率为20,检出限为0.015μg/L,采样频率为26次/h,线性范围为0.05~1.00μg/L,相对标准偏差(RSD)为1.8%(0.50μg/L)。利用本方法分离富集并测定了标准海水样品NASS-5及近海水样中的铜含量,并进行了加标回收实验。     

流动注射-火焰原子吸收光谱法测定痕量铅——磷酸盐沉淀吸附在线富集

在流动注射-火焰原子吸收光谱法(FI-FAAS)测定铅(Ⅱ)的流路中设计了铅(Ⅱ)的磷酸盐沉淀在线富集的编结反应器,痕量铅(Ⅱ)与2.0×10-9mol·L-1磷酸二氢钾溶液在微酸性条件下在反应器中反应.当试样溶液的进样体积固定为8.00 mL,采用的富集流速为4.4 mL·min-1,富集时间为90 S,生成的铅(Ⅱ)的磷酸盐沉淀吸附于聚四氟乙烯反应管的内壁,毋需过滤,直接用2.0 mol·L-1硝酸流入管内使铅(Ⅱ)的沉淀溶解,溶液中铅(Ⅱ)按选定条件进行FAAS检测.按上述条件,可使增强系数(N)达到20,铅(Ⅱ)的检出限(3σ)达到23μg·L-1.对铅(Ⅱ)0.50 mg·L-1的标准溶液平行测定6次,算得测定结果的相对标准偏差为3.1%.用此方法分析了2件粉饼样品,测定值的相对标准偏差(n=6)分别为2.2%和4.1%.以此样品作基体进行回收试验,测得平均回收率为91%.     

汞的形态分析研究 Ⅱ.固相萃取预富集-液相色谱分离测定不同形态的有机汞

本文报道了固相萃取预富集处理样品继以液相色谱分离测定不同形态痕量有机汞的方法.二乙基二硫代氨基甲酸钠(DDTC)作络合剂及甲醇作洗脱液的预富集系统能在线富集甲基汞(MeHg)、乙基汞(EtHg)和苯基汞(PhHg).用于测定加标海水中MeHg、EtHg和PhHg,回收率分别为96.9％、102.4％和98.0％;相对标准偏差分别为3.5％、5.0％和5.0％;检测下限分别为 1.0μg/L、1.2 μg/L和 1.2 μg/L.     

硫代乙酰胺键合硅胶在线选择性固相萃取火焰原子吸收测定环境样品中痕量铜

以制备的硫代乙酰胺键合硅胶为微柱填充材料,建立酸性条件(pH 1 0)下流动注射微柱选择性预富集,0.6 mol/L硫脲溶液洗脱,火焰原子吸收测定环境样品中痕量铜的方法。流动注射在线固相萃取的最佳采样流速为8.0 mL/min;最佳洗脱流速为5.0 mL/min,时间为60 s。在优化的条件下,采样体积为10和50 mL时,线性范围分别为2.0～100.0μg/L和0.5～30.0μg/L;检出限(3σ)分别为0.36和0.07μg/L;富集倍数分别为80和170;相对标准偏差分别为(n=9)3.5%和2.0%。研究了环境样品中常见阴阳离子对测定的干扰。应用于灌木枝叶样品(GBW07602)、标准模拟水样(GBW08608)样品和环境样品中铜的分离与富集,取得满意结果。     

流动注射在线分离富集-火焰原子吸收光谱法测定水中镍(Ⅱ)

应用D412螯合树脂作为富集柱填充物,将在线分离富集装置与火焰原子吸收光谱法联用测定水中镍(Ⅱ)的含量。优化的试验条件如下:1富集柱采用干法填充;2吸附介质的p H为6;3进样速率为5 m L·min-1;4 3 mol·L-1硝酸溶液(洗脱剂)用量为2.5 m L;5洗脱速率为7.5 m L·min-1。镍的质量浓度在50μg·L-1以内与其吸光度呈线性关系,检出限(3s)为0.35μg·L-1。方法用于自来水和河水样品的分析,加标回收率在96.0%~101%之间,测定值的相对标准偏差(n=7)在2.5%~3.1%之间。     

流动注射壳聚糖在线微柱预富集电热原子吸收光谱法测定痕量Cr(VI)

以天然高分子材料壳聚糖作在线预富集柱填料,流动注射与电热原子光谱联用测定痕量Cr(VI)。采样体积5.80mL,采样频率22样/h,富集倍数51倍,线性范围0.02μg/L～0.12μg/L,该方法的检出限(3s,n=11)0.69ng/L,相对标准偏差5.1%(CCr(VI)=0.10μg/L,n=11)。将该方法用于环境水样、茶叶样品和头发样品中Cr(VI)的测定,结果满意。     

分散固液微萃取在线热洗脱原子荧光法测定矿泉水中的痕量汞

研究制备了CI/SiO2/PDMS固相萃取剂,建立了分散固液微萃取在线热洗脱原子荧光联用测定矿泉水中痕量汞的方法。方法使用分散剂将CI/SiO2/PDMS均匀分散于样品溶液中,吸附并富集Hg2+与DDTC形成的Hg-DDTC螯合物。用磁子吸附收集固相萃取剂,并置于石英管中。利用电磁感应加热技术,在线加热洗脱,原子荧光法定量。方法的富集倍数达30倍,检出限为6.0ng/L;精密度RSD为3.8%(n=11,ρ=0.1μg/L)。     

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.     

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.     

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.     

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.     

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.     

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.     

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.