利用碳纳米管固相萃取气相色谱法对水中有机氯农药和多氯联苯的测定

研究利用碳纳米管作为固定相,萃取水中4种有机氯农药(Heptachlor、 Aldrin、 Dieldrin、 Endrin)和5种多氯联苯(PCB052、 101、 138、 153、 180),并用GC/ECD测定.建立了碳纳米管柱SPE/GC/ECD同时测定水中4种有机氯农药和5种多氯联苯的分析方法.通过空白加标和样品基质加标实验考察了方法性能,测得碳纳米管柱萃取的方法检出限为0.10～0.27μg·L-1,相对标准偏差为8.61%～19.3%,9种目标化合物的回收率在62～0%之间.     

双抗体夹心酶联免疫检测法测定蓖麻毒素

建立了双抗体夹心酶联免疫法检测蓖麻毒素的方法。优化了最佳蓖麻毒素多克隆抗体包被浓度和包被方法、蓖麻毒素单克隆抗体工作浓度、酶标记二抗体工作浓度和显色时间等实验条件。方法的线性范围在1.2~10.0μg/L之间,线性回归方程y=0.05x 0.42,相关系数为0.9962,检出限为0.2μg/L。将该方法用于检测实际水样蓖麻毒素加标样品,回收率为91.7%~104.0%;检测实际土壤加标样品,回收率为83.3%~98.0%;检测奶粉加标样品,回收率为83.3%~94.0%;检测实际血液加标样品,回收率为75.0%~82.0%。     

快速溶剂萃取-气质联用法同时测定纺织品中12种有机磷农药

使用体积分数5%的丙酮水溶液为萃取剂,采用快速溶剂萃取仪萃取纺织品中的有机磷。萃取到丙酮水溶液中的有机磷用碳纳米管吸附后,采用少量二氯甲烷将其从碳纳米管中洗脱,洗脱液中的有机磷用气相色谱-质谱联用仪测定。该法可同时测定纺织品中的12种有机磷,方法的平均加标回收率为75%~95%,相对标准偏差(RSD)在8%以内,检出限小于0.5 mg/kg,满足分析要求。     

电感耦合等离子体原子发射光谱(ICP-AES)法测定含硅镁合金中营养元素锶和钙

采用氢氟酸溶解硅,高氯酸冒烟除氢氟酸处理,利用电感耦合等离子体原子发射光谱(ICPAES)法测定生物医用可吸收含硅镁合金中营养元素锶和钙。对仪器参数以及被测元素的谱线选择进行了讨论。在选定最佳条件下,探讨了检测方法中检出限、精密度及加标回收率等指标,方法相对标准偏差小于1%(n=5),加标回收率为100.6%~117.2%。方法实用性强,已成功应用于含硅镁合金中锶和钙的测定。     

磁性多壁碳纳米管固相萃取-气相色谱-质谱法检测水样中的13种邻苯二甲酸酯类化合物

建立了磁性多壁碳纳米管(MWCNTs)固相萃取结合气相色谱-质谱检测水样中13种邻苯二甲酸酯类化合物(PAEs)的方法。优化了萃取时间、水样pH值、解吸溶剂的种类和用量、解吸时间等影响萃取效率的主要条件。最终确定萃取时间为10 min,水样pH 5～7,解吸溶剂为2 mL丙酮,解吸时间为5 min。在优化的条件下,各组分的萃取回收率为89.7%～100.5%。方法具有较高的灵敏度,检出限(信噪比(S/N)为3)为0.08～0.47 μg/L。3种实际样品的加标回收率为84.5%～107.5%,相对标准偏差为1.9%～12.8%。该方法操作简便、省时,准确、灵敏、环保,可用于水样中PAEs的检测,并成功地应用于自来水、瓶装饮用水和湖水样品的分析,13种PAEs均未检出。     

ICP-MS法测定LED有机硅封装胶中铂

建立了混酸消解,ICP-MS法直接测定LED有机硅封装胶中Pt的分析方法,并对消解方法、ICP-MS工作参数及条件进行了优化和选择。LED封装胶用HNO_3+HClO_4+HF混酸体系消解后加入Cs为内标,用ICP-MS直接检测。方法的检出限为0.1 ng/mL,定量限为0.3 ng/mL。对5种不同含量水平的实际样品分析结果表明,RSD为0.8%~2.8%,加标回收率为96%~103.5%,满足分析的要求。     

气相色谱法测定创可贴中环氧乙烷和氯乙醇

将创可贴置于顶空瓶中,在已恒温60℃的烘箱中放置30 min,抽取瓶中气体进样检测环氧乙烷,并通过外标法定量。将创可贴置于密封瓶中,加5 mL浸提液,25℃下浸提24 h后进样检测氯乙醇,并通过外标法定量。气相色谱法检测环氧乙烷的加标回收率为93.1%～97.5%,检出限(3S/D)为0.1μg/g。气相色谱法检测氯乙醇的加标回收率为93.2%～99.3%,检出限(3S/D)为0.05 mg/L。     

磁性碳纳米管固相萃取-原子荧光光谱法测定水中痕量镉

建立了检测水中痕量镉的磁性固相萃取-原子荧光光谱法。制备磁性碳纳米管,以其作为固相萃取吸附剂用来萃取和富集水中的痕量镉,采用氢化物发生-原子荧光光谱法进行检测。在最佳条件下,镉在0.05~5.0μg·L-1范围内呈线性,检出限(3σ)为1.6 ng·L-1。加标回收率在97.1%~101%之间,测定值的相对标准偏差在1.6%~4.8%之间。方法用于分析标准物质,测定值与认定值相符。     

碳纳米管修饰电极离子色谱电化学法测定盐酸麻黄碱

采用阴离子交换分离,碳纳米管修饰电极安培检测离子色谱电化学法测定盐酸麻黄碱.在优化条件下,用碳酸钠溶液和甲醇溶液混合溶液为淋洗液,用碳纳米管修饰玻碳电极,在0.8 V电位处进行直流安培检测.结果发现在碳纳米管修饰玻碳电极后盐酸麻黄碱的电流响应值比未修饰前大大增加,方法的灵敏度比未修饰电极提高了10倍,用未修饰电极测定的检出限为2.4 μg·L-1,用修饰电极测定的检出限为0.2 μg·L-1,样品加标回收率为103.6%..     

气相色谱法同时测定花生中12种有机磷农药残留量

建立了气相色谱法同时测定花生中12种有机磷农药残留量的方法.花生中有机磷农药残留通过乙腈提取,经液-液分配后有机相浓缩以丙酮定容,应用氮磷检测器(NPD)检测.除敌百虫和杀扑磷的检测限分别为20、50 μg/kg以外,其余10种有机磷农药检测限均为10 μg/kg.加标回收率为68.70%～108.45%,测定结果的相对标准偏差为3.05%～19.10%(n=5).该法与单独测定这12种有机磷农药的加标回收率和相对标准偏差基本符合.     

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.     

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.     

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.     

Highly regioselective Buchwald–Hartwig amination at C-2 of 2,4-dichloropyridine enabling a novel approach to 2,4-bisanilinopyridine (BAPyd) libraries

The highly regioselective Buchwald–Hartwig amination at C-2 of the cheap and readily accessible reagent, 2,4-dichloropyridine with a range of anilines and heterocyclic amines is described. This new methodology is robust and provides a facile access to 4-chloro-N-phenylpyridin-2-amines on 0.25 mol scale. These intermediates undergo a further Buchwald–Hartwig amination at higher temperature to enable rapid exploration of the chemical space at C-4 and to provide a library of 2,4-bisaminopyridines.     

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.     

Chemistry of heterocyclic compounds at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, over 50 years (Review)

The review contains a concise historical account and information on the most significant researches undertaken by the staff at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences on the Chemistry of Heterocyclic Compounds. Dedicated to Academician of the Russian Academy of Sciences B. A. Trofimov on his 70th jubilee. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1443–1502, October, 2008.     

Sulfur-directed metal-free and regiospecific methyl C(sp3)–H imidation of thioanisoles

Regiospecific and direct imidation of the methyl C(sp³)–H bond of thioanisoles is realized under mild and metal-free conditions with N-fluorobis(benzenesulfonyl)imide as an oxidant and nitrogen source. Proposed mechanism suggests that thionium ion intermediates and a Pummerer-type reaction are involved. The imidation has advantages such as high step-economy, excellent functionality tolerance, and regiospecificity, giving structurally diverse imidation products.     

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.