快速溶剂萃取–凝胶渗透色谱净化–气相色谱质谱法测定土壤中邻甲苯胺含量

以快速溶剂萃取–凝胶渗透色谱净化–气相色谱质谱法测定土壤中邻甲苯胺的含量。土壤样品经ASE–350快速溶剂萃取仪萃取,萃取液用凝胶渗透色谱净化浓缩后,用全扫描模式(SCAN)采集气相色谱–质谱法测定土壤中的邻甲苯胺含量。该方法检出限为0.01 mg/kg,加标回收率为78.3%~95.5%,测定结果的相对标准偏差为2.35%~14.9%(n=6)。该方法具有分离效果好、灵敏度高、重现性好、前处理操作简便及纯化效果好等优点,可用于测定土壤中邻甲苯胺的含量。     

微波萃取气相色谱–质谱法测定发泡塑料中的甲酰胺

建立了测定发泡塑料中甲酰胺含量的气相色谱–质谱法。以乙醇于80℃微波萃取样品,用气相色谱–质谱联用仪SIM模式外标法定量测定发泡塑料中甲酰胺残留量。在优化的实验条件下,甲酰胺的质量浓度在0~10.0μg/m L范围内与色谱峰面积成良好的线性关系,线性相关系数为0.999 8。甲酰胺的检出限为1.0 mg/kg,样品加标回收率为97.5%~102.3%,测定结果的相对标准偏差为0.57%~3.07%(n=6)。该方法样品处理简单、快速,适用于发泡塑料中甲酰胺的日常检测。     

气相色谱–质谱法测定塑胶中磷酸三(二甲苯)酯

建立气相色谱–质谱联用测定塑胶中磷酸三(二甲苯)酯类化合物的方法。以甲苯为萃取溶剂,对样品进行萃取,选用DB–5HT气相分离色谱柱,用气相色谱–质谱联用仪对磷酸三(二甲苯)酯进行检测。在优化实验条件下,磷酸三(二甲苯)酯在14 min内可以获得良好的分离,其质量浓度在0.05~10 mg/L范围内与色谱峰面积呈良好的线性关系,线性相关系数r=0.999 8,检出限为0.05 mg/L。测定结果的相对标准偏差为3.03%~7.32%(n=7),加标回收率为95.3%~114.6%。该方法简便快捷,灵敏度高,可用于塑胶中磷酸三(二甲苯)酯的快速检测。     

快速溶剂萃取-凝胶渗透色谱净化-气相色谱-质谱法测定土壤中11种半挥发性有机物

建立了快速溶剂萃取–凝胶渗透色谱净化–气相色谱–质谱法测定土壤中11种半挥发性有机物的分析方法。取样量为10.0 g,萃取溶剂为丙酮–二氯甲烷(体积比为3∶7),使用凝胶渗透色谱净化,气相色谱–质谱仪进行测定。11种半挥发性有机物的质量分数在0.1-5 mg/kg的范围内,相对响应因子的相对标准偏差小于15%,方法的检出限为0.04-0.06 mg/kg,当加标量为0.25、0.5、1 mg/kg时,测定结果的相对标准偏差分别为4.8%-13.7%、3.8%-9.5%、3.4%-10.8%(n=6),加标回收率为55%-110%。该方法适用于土壤中11种半挥发性有机物的检测。     

气相色谱–质谱法测定食用植物油中23种农药残留

建立了测定食用植物油中23种农药残留的气相色谱–质谱联用方法。采用固相萃取,以乙腈超声提取,经过PSA,C_(18)柱进行净化,用气相色谱–质谱法测定,外标法定量。23种农药在0.01~1.0 mg/L范围内与色谱峰面积线性关系良好,相关系数为0.997 3~0.999 7,方法检出限为5~15μg/kg。测定结果的相对标准偏差为2.25%~9.40%(n=6),加标回收率为78.4%~127.3%,可以满足食用植物油中多种农药残留的同时分析。采用该方法对国内市场常见的食用植物油进行检测分析,所检测的农药残留均在国家标准的限量范围内。     

气相色谱法检测仿真饰品中的卤代烃

建立了仿真饰品中残留卤代烃的气相色谱检测方法。对比分析了不同溶剂和萃取时间对卤代烃提取效果的影响,应用超声提取法进行样品前处理,使用DB–624气相色谱柱及35~245℃的程序升温条件,以ECD检测器进行检测分析,仿真饰品中7种卤代烃可以实现良好的分离。色谱峰面积与卤代烃的质量浓度在1.0~20.0 mg/L范围内线性相关,相关系数均大于0.990。7种卤代烃加标回收率为81.2%~98.2%,测定结果的相对标准偏差为1.51%~2.52%(n=6)。该方法适用于检测不同材质仿真饰品中卤代烃的含量。     

气相色谱-质谱法测定轨道交通塑料产品中18种有害物质

建立气相色谱–质谱联用检测轨道交通塑料产品中的18种有毒有害物质的方法。用甲苯超声萃取60 min,选用DB–5HT(15 m×0.25 mm, 0.1μm)色谱柱,气相色谱–质谱法对样品进行检测。在优化的分析条件下,18种待测物质于20 min内获得对称的色谱峰,分离效果良好。待测物质的线性范围为0.5～4.5 mg/L,线性相关系数均在0.999以上,检出限达到0.5 mg/L,测定结果的相对标准偏差小于7%(n=6),样品加标回收率为85.3%～107.9%。该测试方法方便快速,测试结果准确、可靠,可以满足轨道交通塑料产品中多种有害物质的测定要求。     

固相萃取–气相色谱–串联质谱法测定塑料食品包装材料中3种抗氧化剂的残留量

建立了气相色谱–串联质谱法测定塑料食品包装材料中抗氧化剂二丁基羟基甲苯(BHT)、丁基羟基茴香醚(BHA)和特丁基对苯二酚(TBHQ)残留量的分析方法。样品采用环己烷–乙酸乙酯混合溶剂超声萃取,经固相萃取法富集和净化,采用气相色谱–串联质谱在多反应监测模式下进行测定。结果表明,3种抗氧化剂质量浓度在0.05~20 mg/L范围内线性关系良好,线性相关系数大于0.999;BHT,BHA,TBHQ的检出限分别为0.005,0.01,0.03mg/kg;平均添加回收率为88.7%~104.0%;测定结果的相对标准偏差小于5.5%(n=6)。该方法操作简便,灵敏度高,重复性好,可用于塑料食品包装材料中抗氧化剂BHT,BHA,TBHQ残留量的测定。     

分散液液微萃取–气相色谱–质谱法测定水中3种硝基甲苯同分异构体

建立分散液液微萃取-气相色谱–质谱测定水中3种硝基甲苯同分异构体的方法。水中硝基甲苯用分散液液微萃取富集后经CD–5MS色谱柱分离,采用气相色谱质谱法测定。3种硝基甲苯同分异构体的质量浓度在0.0~40.0μg/L范围内与色谱峰面积均具有良好的线性关系,相关系数大于0.999,方法检出限为0.03~0.04μg/L。测定结果的相对标准偏差均小于2%(n=7),样品加标回收率为90.2%~95.9%。该方法操作简便,萃取效率高,有机试剂用量少,适用于环境水样中硝基甲苯的检测。     

快速溶剂萃取–气相色谱质谱法测定土壤中戊唑醇残留量

建立快速溶剂萃取–气相色谱质谱法测定土壤中戊唑醇残留量的分析方法。土壤样品经ASE–350快速溶剂萃取仪萃取,萃取液用硅酸镁(弗罗里硅土)柱净化浓缩,然后用选择离子监测/全扫描(SIM/SCAN)模式,气相色谱–质谱法测定土壤中的戊唑醇含量。该方法检出限为0.008 mg/kg,加标回收率为84.0%~97.5%,测定结果的相对标准偏差为2.2%~11.6%(n=6)。该方法具有分离效果好,灵敏度高,重现性好,前处理操作简便等优点,可用于测定土壤中戊唑醇的残留量。     

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.     

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.     

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.     

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.