加速溶剂萃取-超高效液相色谱-串联质谱法测定沉积物中的8种环境内分泌干扰物

取经前处理后的沉积物样品(5.000g)与中性氧化铝粉25g充分混匀,按规定条件用丙酮-甲醇(1+1)混合液进行加速溶剂萃取其中的8种内分泌干扰物。所得萃取液吹氮浓缩至2mL,加水400mL并调节pH至3,溶液经HLB固相萃取小柱净化。小柱用氮气吹干后,用丙酮8mL洗脱。洗脱液经处理后进行超高效液相色谱-串联质谱分离。以BEH C18柱为固定相,以不同体积比的甲醇和0.1%(体积分数)氨水溶液为流动相进行梯度洗脱。在质谱分析中,采用电喷雾负离子源和多反应监测模式。8种化合物的质量浓度在2.0~100.0μg·L~(-1)范围内呈线性,检出限(3s)在0.03~0.05μg·kg~(-1)之间。按标准加入法在3个浓度水平上进行回收试验,回收率在62.8%~104%之间,测定值的相对标准偏差(n=6)在2.8%~15%之间。     

气相色谱-串联质谱法测定纸质及塑料食品包装材料中12种多环芳烃的含量

取经剪碎或粉碎的纸质或塑料包装材料样品2.000g,加入500μg·L-1 D8-萘同位素溶液100μL作内标后,加入正己烷-丙酮(1+1)混合液10mL和水10mL,超声萃取30min。取上层有机相,于其中加入新型吸附剂净化2次(每次加25mg)。经净化的有机相按仪器工作条件进行分析。在气相色谱分离中用HP-5MSUI色谱柱为固定相,在质谱分析中采用多反应监测模式。12种多环芳烃的质量浓度在一定的范围内与其峰面积呈线性关系,方法的检出限(3S/N)在0.04~0.59μg·L-1之间。以空白样品为基体进行加标回收试验,所得回收率在77.0%~105%之间,测定值的相对标准偏差(n=6)在1.4%~9.3%之间。     

顶空固相微萃取-气相色谱法测定水中16种有机氯农药的含量

取水样(8.00 mL)置于20 mL顶空瓶中,加入3 g氯化钠至饱和。采用聚二甲基硅氧烷/二乙烯基苯(PDMS/DVB)萃取纤维头,在振动速率250 r·min-1下于70℃萃取60 min。萃取后将PDMS/DVB萃取纤维头插入气相色谱仪,解吸4 min,采用HP-5色谱柱为固定相进行色谱分离。16种有机氯农药的质量浓度在一定范围内与其峰面积呈线性关系,检出限(3.143s)为0.001~0.005μg·L-1。按标准加入法进行回收试验,回收率在70.6%~132%之间,测定值的相对标准偏差(n=6)在3.7%~30%之间。利用上述方法开展了水中有机氯农药的保存试验研究。     

磁固相萃取-高效液相色谱法测定环境水样中双酚A

采用磁固相萃取-高效液相色谱法测定环境水样中双酚A的含量。优化的试验条件如下:1 50mL水样中加入20mg磁性微球进行萃取;2水样的pH为3.0;3萃取时间为15min;4解析溶剂为甲醇(80+20)溶液;5解析时间为10 min。采用C18色谱柱为分离柱,以甲醇-水(85+15)混合液为流动相,在检测波长224nm处进行测定。双酚A的质量浓度在5.0~500μg·L-1范围内与其峰面积呈线性关系,方法的检出限(3S/N)为1.0μg·L-1。方法应用于环境水样的分析,加标回收率在81.4%~109%之间,测定值的相对标准偏差(n=6)在5.7%~8.6%之间。     

微型液液萃取-气相色谱-质谱法测定烟用香料中丁酸和乳酸的含量

样品0.500 0g置于10mL烧杯中,用0.1mol·L~(-1)氢氧化钾-甲醇溶液调节pH至8~9,于100℃将水分挥干。残渣用硫酸-甲醇(5+95)溶液10 mL溶解,并于70℃酯化反应30min。取甲酯化后的溶液200μL采用自主设计的微型液液萃取装置,以二氯甲烷1mL为萃取剂进行萃取,再加入水1mL进行振荡萃取。所得萃取液采用气相色谱-质谱法(GC-MS)测定其中丁酸和乳酸的含量。结果表明:丁酸和乳酸的质量浓度在0.10~50.00mg·L~(-1)内与其峰面积呈线性关系,检出限(3S/N)分别为0.1,0.4 mg·kg~(-1)。按标准加入法进行回收试验,回收率为97.7%~108%,相对标准偏差(n=5)为0.60%~12%。     

高效液相色谱-电感耦合等离子体质谱法同时测定烟用接装纸中三价铬与六价铬的含量

烟用接装纸样品1.000g置于50mmol·L-1氢氧化钠溶液15mL中回旋振荡提取2h,过滤。取其提取液0.5mL,用0.1mol·L-1盐酸溶液中和至pH 7.0后,加入0.1mol·L-1Na2-EDTA溶液5mL,在80℃条件下反应20min。所得溶液进行色谱分离,用Dionex AS19色谱柱为固定相,用pH 7.0的0.15mol·L-1硝酸铵溶液作为流动相。在质谱分析中,用氦气作为碰撞气,可减小35Cl 16 O1 H+、40 Ar12C+对52Cr+的质谱干扰。结果表明:Cr(Ⅲ)和Cr(Ⅵ)的线性范围依次为20.0~1 000μg·L-1,0.20~10.0μg·L-1,检出限(3s)分别为4.81,0.63μg·kg-1。在3个浓度水平上进行加标回收试验,测得两者的回收率依次在95.2%~104%和80.0%~116%之间,测定值的相对标准偏差(n=7)依次在2.5%~3.1%和2.6%~3.6%之间。     

高效液相色谱法测定食品包装材料中双酚A的含量

样品(2.000 0 g)经甲醇50 mL超声提取60 min,提取液用水稀释至100 mL,经0.22μm滤膜过滤后进行色谱分离。以Agilent Eclipse plus C18柱为固定相,50 mmol·L-1柠檬酸缓冲液(p H6.0)-甲醇(45+55)混合液为流动相。电化学检测器的检测池电压为400 m V(ECD1)和575 m V(ECD2)。双酚A的质量浓度在0.2~20.0μg·L-1内与其峰面积呈线性关系,检出限(3S/N)为3.3μg·kg-1。按标准加入法在3个浓度水平上进行回收试验,回收率在95.6%~98.2%之间,测定值的相对标准偏差(n=5)在2.1%~5.3%之间。     

分散液液微萃取-气相色谱-质谱法测定长江水体中18种苯系物

取经滤膜过滤的长江水样8.00mL,加入含四氯乙烯10μL的丙酮0.50mL,样品中的苯系物在几秒钟内即被萃取至四氯乙烯微小液滴中。经高速离心,萃取相沉积在离心管底部,移取萃取相8μL置于进样瓶中供气相色谱-质谱分析。在气相色谱分离中用HP-INNOWAX毛细管柱为固定相,在质谱分析中采用全扫描和选择离子检测模式。18种苯系物的质量浓度在1 000μg·L-1以内与其峰面积呈线性关系,方法的检出限(3S/N)在0.055~0.156μg·L-1之间。加标回收率在66.5%~106%之间,相对标准偏差(n=5)在3.1%~8.6%之间。     

固相萃取-高效液相色谱-原子荧光光谱法联用测定水中无机汞(Ⅱ)及有机汞

采用固相萃取-高效液相色谱-原子荧光光谱法联用技术测定了水样中无机汞及有机汞。水样流经以DDTC溶液改性的C18固相萃取小柱。用含有10%(体积分数)乙腈的混合洗脱液4mL,分4次,以1~2mL·min-1流量从小柱上将3种形态的汞洗脱。收集洗脱液,混匀,过滤后通过Venusil MP C18色谱柱,用乙腈、145mmol·L-1乙酸铵溶液和20mmol·L-1半胱氨酸溶液(5+45+50)混合液作为流动相进行色谱分离。根据选定的形态分析条件,用原子荧光光谱法进行测定。汞质量浓度在0.5~20μg·L-1范围内与其峰面积呈线性关系,汞(Ⅱ)、甲基汞、乙基汞的检出限(3S/N)依次为1.6,0.5,1.2ng·L-1。加标回收率在71.2%~95.2%之间,测定值的相对标准偏差(n=6)在4.9%~10%之间。     

超高效液相色谱-串联质谱法测定玩具材料中六溴环十二烷的3种同分异构体的含量

纺织纤维材质的玩具样品(0.5g)用丙酮10mL于60℃超声提取30min。提取液吹氮蒸干,残渣用甲醇溶解并定容至5mL。橡胶、塑料材质的玩具样品(0.5g),用甲苯-甲醇(10+1)混合液进行索氏提取。将提取液蒸至近干,残渣用甲醇溶解并定容至5mL,所得溶液供超高效液相色谱-串联质谱分析。用Acquity UPLC BEH C18色谱柱作固定相,用(A)甲醇-乙腈(4+1)混合液和(B)10mmol·L-1乙酸铵溶液(5+95)混合液作流动相进行洗脱,实现了六溴环十二烷的3种同分异构体的色谱分离。α,β,γ-六溴环十二烷的质量浓度均在1.0~2.0mg·L-1范围内呈线性,3种异构体的检出限(3S/N)依次为0.1,0.2,0.5μg·L-1。加标回收率在70.0%~112%之间,测定值的相对标准偏差(n=6)在0.070%~9.9%之间。     

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.