中心切割GC-MS法分析煤液化油中的酚类化合物

使用碱洗提酚法提取煤液化油中的酚类化合物,然后结合Deans Switch装置和LTM色谱柱模块,采用中心切割气相色谱(GC)-质谱(MS)法对提取的酚类化合物进行定性。采用GC建立标准曲线,对煤液化油中主要酚类化合物的质量分数进行测定,并测定了煤液化油中邻甲基苯酚、2-乙基苯酚、4-丙基苯酚和5-茚酚4种酚类化合物的加标回收率。结果表明,在煤液化油中共定性出51种酚类化合物,测定了其中的35种酚类化合物的质量分数,其量占煤液化油总量的2.54(wt)%,苯酚和烷基苯酚占35种酚类化合物的88.2(wt)%。煤液化油中4种酚类化合物的加标回收率高,重复性好。     

气相色谱法测定纺织品中五氯苯酚残留量

建立了纺织品中五氯苯酚残留量的测定方法。试样用碳酸钾溶液提取 ,加乙酸酐乙酰化后 ,以正己烷提取乙酰化五氯苯酚 ,用气相色谱 电子俘获检测器 (GC ECD)测定 ,以外标法定量。五氯苯酚的检出限 0 .0 2mg·kg-1,加标回收率 90 %～ 10 5 % ,相对标准偏差≤ 6.7%。     

煤液化油中碱性氮化物的分析方法及分布研究

采用酸液萃取的方法从煤液化油中提取碱性氮化物,气相色谱-质谱联用(GC-MS)和氮化学发光检测器(GC/NCD)进行定性定量。从分析结果可见,碱性氮化物可以通过酸液萃取与油样达到较完全的分离。用GC-MS定性出全馏程煤液化油中含有38种碱性氮化物,主要为吡啶类、苯胺类以及喹啉类氮化物。用GC/NCD对18种全馏程煤液化油中的碱性氮化物定量分析,结果显示其占碱性氮化物总量的88.9%,其中吡啶类占碱性氮化物总量的24.48%,苯胺类占37.98%,喹啉类占26.48%。     

超声波提取-气相色谱法测定油田区土壤中21种酚类化合物

采用超声波提取—气相色谱法测定油田区土壤中21种酚类化合物,主要研究了提取时间及净化条件等对测定结果的影响.对比了加压流体萃取与超声波提取方式对回收率的影响,结果表明:超声波提取法回收率优于加压流体萃取法,其中2,4-二硝基酚和4-硝基酚两种化合物比加压流体萃取法回收率提高了30%.以10.0 g土壤样品计,酚类化合物的检出限为0.01～0.05 mg/kg,样品加标回收率为81.5%～110%,精密度为2.6%～11%.经有证标准物质验证,相对误差为2.6%～14%.试验结果表明,超声波提取法适合于油田区土壤中21种酚类化合物的测定.     

改进的五氟苄基溴衍生化反应测定水中酚类化合物

建立了气相色谱-质谱法测定水中6种酚类化合物(2,6-二氯酚、2,4-二氯酚、2,4,6-三氯酚、2,4,5-三氯酚、2,3,4,6-四氯酚和五氯酚)的方法。样品经二氯甲烷-乙酸乙酯混合溶剂萃取后,用旋转蒸发浓缩至1 mL,加入五氟苄基溴进行改进版衍生化反应,产物用DB-5 mS毛细管柱分离,采用选择离子监测模式测定。酚类化合物的检出限在0.05~0.13μg/L之间。目标物在0.05~1 mg/L范围内线性关系良好,相关系数R²为0.9972~0.9983。以地下水水样为基体,加入3个浓度水平的标准溶液进行加标回收实验,加标回收率在60.4%~109.6%,相对标准偏差在0.1%~12%之间。     

索氏提取-气相色谱法测定高含水率土壤中 21种酚类化合物

高含水率土壤样品与无水硫酸钠混合均匀后,以二氯甲烷-正己烷(2+1)混合液为提取剂进行索氏提取,提取液经氢氧化钠溶液净化,再经酸化后由二氯甲烷-乙酸乙酯(4+1)混合液提取,最后进行浓缩,采用气相色谱法测定浓缩液中21种酚类化合物的含量。用HP-5色谱柱(30m×0.25mm,0.25μm)分离,氢火焰离子化检测器检测。21种酚类化合物的质量浓度均在1.0～100.0mg·L~(-1)内与其对应的峰面积呈线性关系,检出限为0.01～0.07mg·kg~(-1)。以空白样品为基体进行加标回收试验,所得回收率为71.4%～95.1%,测定值的相对标准偏差(n=6)为1.0%～11%。     

超高效液相色谱-串联质谱法测定染发剂中7种酚类化合物

提出了应用超高效液相色谱-串联质谱法同时测定染发剂中4-氨基-2-硝基苯酚、3-二乙氨基酚、2-氨基-4-氯苯酚、2-氨基-5-硝基苯酚、2-氨基-3-硝基苯酚、1,7-二羟基萘酚和2,3-二羟基萘酚等7种酚类化合物的方法。采用甲醇萃取染发剂中酚类成分,经WatersAcquityUPLCTMBEHC18色谱柱分离,外标法定量,多反应监测模式采集质谱数据。7种酚类化合物的检出限(3S/N)均低于50.0μg.L-1。在10,20,50μg.g-1三个添加水平下,7种酚类化合物的回收率在68.8%～112.5%之间,相对标准偏差(n=6)在1.58%～12.61%之间。     

高效液相色谱-串联质谱法同时测定空气中10种酚类化合物的含量

提出了高效液相色谱-串联质谱法同时测定空气中苯酚、4-硝基酚、3-甲酚、2-氯酚、2,4-二甲酚、2,4-二氯酚、2,4,6-三氯酚、五氯酚、1-萘酚、2-萘酚等10种酚类化合物含量的方法。用XAD-7采样管采样,用甲醇洗脱;收集2.0 mL洗脱液,分取0.5 mL,再用水定容至1.0 mL,过0.22μm滤膜。以Kinetex C₁₈色谱柱为固定相,以不同体积比的甲醇-水的混合溶液为流动相进行梯度洗脱。分离后的酚类化合物经大气压化学电离源电离,多反应监测模式检测,外标法定量。结果表明：10种酚类化合物标准曲线的线性范围均为10～1 000μg·L^-1,检出限(3.143s)为0.2～1.7μg·m^-3;对空白样品进行3个浓度水平的加标回收试验,回收率为69.3%～102%,测定值的相对标准偏差(n=6)为1.1%～9.6%;方法用于10个实际空气样品分析,其中有3个样品检出苯酚,质量浓度为23.3～40.2μg·m^-3。     

固相萃取-衍生化-气相色谱-质谱法同时测定环境水中双酚A和9种烷基酚类化合物的含量北大核心CSCD

提出了固相萃取-衍生化-气相色谱-质谱法同时测定环境水中双酚A(BPA)和9种C4~C9烷基酚类化合物(APs,包括4-叔丁基苯酚、4-丁基苯酚、4-戊基苯酚、4-己基苯酚、4-叔辛基苯酚、4-庚基苯酚、壬基酚、4-辛基苯酚和4-壬基苯酚)含量的方法。取500 mL水样,用50%(体积分数)盐酸溶液调节pH小于2,以50 mL·min^(-1)速率通过以苯乙烯/二乙烯苯聚合物为吸附剂的SDB-XC固相萃取膜,用5 mL丙酮和10 mL二氯甲烷洗脱。收集洗脱液,加入1 mL正己烷,经10 g无水硫酸钠脱水,用旋转蒸发仪浓缩至约0.5 mL后转移至1 mL容量瓶中。用少量二氯甲烷洗涤浓缩瓶,将洗涤液合并至容量瓶中,再依次加入100μL内标混合溶液和100μL衍生试剂,用二氯甲烷定容至1 mL,室温衍生1 h。上述溶液中各目标物在气相色谱仪中以程序升温和程序升压方式分离,在质谱仪中以选择离子监测模式测定,内标法定量。结果显示:BPA和9种APs标准曲线的线性范围为5.000~500.0μg·L^(-1),检出限为0.002~0.006μg·L^(-1);各目标物在空白加标水样中测定值的相对标准偏差(n=6)为1.2%~15%;方法用于实际地表水、生活污水和工业废水分析,均检出壬基酚和BPA,地表水和生活污水中还检出4-叔辛基苯酚,检出量为0.005~0.657μg·L^(-1),其余APs未检出,实际样品中BPA和9种APs的加标回收率为73.4%~125%。     

气相色谱-质谱法测定化妆品中多种防腐剂

采用超声抽提法对化妆品中的苯甲醇、3-甲基-4-异丙基苯酚、对羟基苯甲酸丁酯和2-苄基-4-氯酚等18种防腐剂进行了气相色谱-质谱法(GC-MS)测定的研究。建立了一种简单、快速、准确测定化妆品中各种防腐剂的测定方法。进行了样品提取溶剂和超声提取时间选择以及线性、回收率、精密度试验。结果表明,该方法能够有效地提取化妆品(口红和香波)中的18种防腐剂,并可对其进行GC-MS分离和鉴定。18种防腐剂的平均回收率为91.66%-100.6%(n=7),相对标准偏差为0.46%-6.23%(n=7),最低检测限为     

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.     

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.     

Facile synthesis of bicyclic 1-arylpyrazol-5-ones

In this Letter, we described a facile method for constructing fused bicyclic 1-arylpyrazol-5-one ring system. We employed various methylene-containing carboxylic acids as the substrates and proved that the pyrazolone ring closure requires activated methylene group in intermediate II. Accordingly, a series of structurally diversified, fused bicyclic 1-arylpyrazol-5-ones was prepared in moderate to high yields using the requisite substrates.