吹扫捕集-气相色谱-质谱法测定地下水中挥发性有机物

应用吹扫捕集-气相色谱-质谱联用法测定地下水中54种挥发性有机污染物(VOC′s)含量.选定在40℃条件下吹扫捕集11 min,取样品溶液10 mL于吹扫瓶中,利用PTA 3000型吹扫捕集器直接进样,经DB-5MS毛细管色谱柱分离,电子轰击电离(EI)全扫描检测,选用特征离子,以内标法进行定量测定;54种VOC′S样品加标回收率在83.2%～115.5%之间,相对标准偏差在0.85%～3.88%之间,方法的检出限范围在0.03～0.12μg·L-1之间.     

吹扫捕集-气相色谱-质谱法测定海岸带表层沉积物中挥发性有机物

应用吹扫捕集-气相色谱-质谱法测定海岸带表层沉积物中28种挥发性有机物的含量。选定在40℃条件下吹扫捕集11min,取样品于吹扫瓶中,利用PTA 3000吹扫捕集仪直接进样,经J&W DB5-MS毛细管色谱柱分离,电子轰击电离全扫描检测,内标法进行定量测定。28种挥发性有机物的方法检出限在0.16～0.38μg.kg-1之间,样品加标回收率在70.7%～115.5%之间,相对标准偏差(n=7)在1.7%～7.8%之间。     

吹扫捕集–气相色谱–质谱法测定地表水中5种硝基苯类化合物

对吹地表水中5种硝基苯类化合物进行吹扫捕集富集,解吸后用气相色谱-质谱联用法同时测定,内标法定量,加入硫酸钠提高方法的灵敏度,优化并验证检测方法。实验结果表明,使用Te Kmer-Dohrmann 3100型吹扫捕集仪,在吹扫温度为45℃、吹扫14 min的条件下测定水质中5种硝基苯类化合物,在0~60μg/L范围内线性关系良好,检出限为0.03~0.05μg/L,加标回收率为91.7%~95.9%,测定结果的相对标准偏差为1.00%~1.84%(n=7)。该方法操作简便、准确度高、重现性好,能够满足地表水中5种硝基苯类化合物的同时测定。     

气质联用仪结合吹扫捕集测定固体废物中挥发性卤代烃

使用岛津GCMS-QP2020 NX气相色谱质谱联用仪结合吹扫捕集CDS 7000E建立了固体废物中30种挥发性卤代烃的测定方法。样品置于棕色吹扫捕集瓶中，挥发性卤代烃经吹扫捕集富集后用GCMS进行分析，以SIM方式进行采集，内标法定量。30种挥发性卤代烃在1.0～20μg/L的浓度范围内相关系数R在0.995以上。2.0μg/L标准溶液连续进样，峰面积RSD为1.21%～8.05%。加标浓度为1.0μg/kg时，平行试验3次，各组分的回收率在69.07%～138.07%之间。该方法前处理简单、灵敏度高，完全满足固废中挥发性卤代烃检测的要求。     

吹扫捕集-气相色谱-质谱法同时测定土壤中27种挥发性有机物

应用吹扫捕集-气相色谱-质谱法测定土壤中27种挥发性有机物的含量。选定在25℃条件下吹扫捕集11min,取样品溶液5mL于吹扫瓶中,利用Tekmar Stratum吹扫捕集器直接进样,经TR-5MS毛细管色谱柱分离,电子轰击电离(EI)全扫描和选择离子扫描检测,内标法进行定量测定。27种挥发性有机物的质量浓度与其峰面积在一定的浓度范围内呈线性关系,方法检出限(3S/N)在0.077～0.69μg·kg~(-1)之间。样品加标平均回收率在86.5%～117.5%之间,相对标准偏差(n=7)在1.6%～8.2%之间。     

吹扫捕集/气相色谱-质谱法测定水中痕量全氟碘烷类化合物

利用吹扫捕集/气相色谱-质谱联用技术,建立了一种同时测定水中9种全氟碘烷类化合物的新方法,并对捕集管的型号、吹扫温度、吹扫时间、解吸时间及盐效应等样品吹扫条件进行了优化。在最佳实验条件下,9种全氟碘烷类化合物在0. 1～100μg·L-1范围内线性关系良好,相关系数(r2)不小于0. 996,方法检出限为5. 6～15 ng·L-1,定量下限为17～36 ng·L-1。在高、中、低3个加标水平下,9种全氟碘烷类化合物的回收率为75. 7%～118%,相对标准偏差为2. 2%～8. 3%。将建立的方法用于某典型污染区域环境水样的分析,检出9种全氟碘烷类化合物,质量浓度为21. 3～469 ng·L-1。     

吹扫捕集–气相色谱质谱联用法测定地表水中6种氯苯类化合物

建立吹扫捕集–气相色谱质谱联用法测定地表水中6种氯苯类化合物的方法。在水样中加入过饱和硫酸钠溶液提高吹扫捕集效率,通过吹扫捕集富集水样中的6种氯苯类化合物,解吸后用气相色谱–质谱联用法同时测定,内标法定量。6种氯苯类化合物在0~60μg/L范围内与定量离子色谱峰面积线性关系良好,线性相关系数为0.999 0~0.999 5,检出限为0.01~0.02μg/L,测定结果的相对标准偏差为1.74%~3.83%(n=6),加标回收率为92.8%~97.9%。该方法操作简便,准确度高,重现性好,能够满足地表水中6种氯苯类化合物的同时测定。     

吹扫捕集-气相色谱-质谱法测定土壤和地下水中四氢呋喃

建立吹扫捕集-气相色谱-质谱法测定土壤和地下水中四氢呋喃。最佳的吹扫捕集条件:吹扫温度为40℃,吹扫时间为15 min,脱附温度为250℃,脱附时间为2 min。四氢呋喃的质量浓度在10～200μg/L范围内与色谱峰面积线性关系良好,相关系数不小于0.990。土壤和地下水中四氢呋喃的检出限分别为1.5、1.4μg/L,标准样品平均加标回收率分别为84.5%、77.2%,测定结果的相对标准偏差分别为3.3%、5.8%(n=6)。该方法适用于土壤和地下水中四氢呋喃含量的检测。     

吹扫捕集气相色谱法测定水中苯系物

采用吹扫捕集-气相色谱法测定生活饮用水中苯系物(笨、甲苯、乙苯、邻、间、对二甲苯、异丙苯、苯乙烯),并对吹扫捕集的条件进行优化,缩短了分析周期,提高了方法的灵敏度和准确度.方法的最低检出浓度为0.9～1.7μg/L,相对标准偏差为0.63%～1.36%(n=7),平均加标回收率为97.4%～101.3%.本方法适合于地表水和生活饮用水中苯系物的测定.     

气相色谱–质谱法测定地表水中硝基苯

建立吹扫捕集–气相色谱–质谱联用法测定地表水中硝基苯的方法。用吹扫捕集法对水样进行前处理,以HP–5弱极性毛细管柱(30 m×0.32 mm,0.25μm)进行分离,质谱法测定水中硝基苯的含量。硝基苯的质量浓度在0.00~60.0μg/L范围内与色谱峰面积线性关系良好,线性相关系数为0.999 4,方法的检出限为0.03μg/L。测定结果的相对标准偏差小于2%(n=7),地表水样品加标回收率在91.2%~96.5%之间。该方法操作简便,检出限低,精密度和准确度高,适用于地表水中硝基苯的测定。     

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%.     

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.     

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.     

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.     

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.     

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.