Concentration and clean-up of trace hydrocarbons from atmospheric particulate matter

Summary The aim of this work is to establish the best conditions for concentration and purification steps in the trace analysis of aliphatic and polycyclic aromatic hydrocarbons (PAH) from atmospheric particulate matter by gas chromatography-flame ionisation detection (GC-FID) and high performance liquid chromatography with ultraviolet and fluorescence detection (HPLC-UV-FL). The best results for the more volatile compound were obtained with a combination of rotary evaporation and a stream of nitrogen (near to 100% for aliphatic hydrocarbons and from 70 to 105% for PAH). Two types of solid phase extraction (SPE)cartridges (Supelclean ^tm LC-Silica SPE tubes and Sep-Pak^? Plus silica cartridges) and glass column were examined for the purification and fractionation step. Blank chromatograms of both types of cartridges analysed by GC-FID made this study difficult, because a PSS (programmed split-splitless) injector was employed thereby increasing the sensitivity. This problem was not observed in the HPLC-UV-FL blank chromatograms of these cartridges. Glass columns filled with silica and alumina were chosen because no interference was found in the GC-FID blank chromatograms and the best recoveries in the fractionation of both aliphatic hydrocarbons and PAH were achieved. This is especially important when aliphatic hydrocarbons concentrations are lower than 1 μg mL⁻¹. Finally, the selected conditions were applied to the analysis of hydrocarbons in real atmospheric particulate samples.     

Monitoring the Hydrolysis of p—Nitrophenyl Acetate Catalyzed by Seryl—histidine with Electrospray Ionization Mass Spectrometry

ＩｎｔｒｏｄｕｃｔｉｏｎＩｎｔｈｅｐａｓｔｄｅｃａｄｅ ,ｉｔｗａｓｆｏｕｎｄｔｈａｔｔｗｏａｍｉｎｏａｃｉｄｒｅｓｉｄｕｅｓ ,ＳｅｒａｎｄＨｉｓ ,ｗｏｒｋａｓｔｈｅａｃｔｉｖｅｓｉｔｅｓｉｎｔｈｅｓｅｒ ｉｎｅｐｒｏｔｅａｓｅ .1 3 Ｉｎｏｕｒｐｒｅｖｉｏｕｓｗｏｒｋ ,ａｄｉｐｅｐｔｉｄｅｓｅｒｙｌ ｈｉｓｔｉｄｉｎｅ (Ｓｅｒ Ｈｉｓ)ｗａｓｆｏｕｎｄｔｏｈａｖｅｔｈｅｐｒｏｔｅｉｎａｎｄｎｕ ｃｌｅｏｓｉｄｅｓｃｌｅａｖａｇｅａｃｔｉｖｉｔｙ .4 7ｐ Ｎｉｔｒｏｐｈｅｎｙｌａｃｅｔａｔｅ (ｐ ＮＰＡ)ｗ…     

Pu（^7Fg）＋H2（X^1∑g^＋,0,0）的分子反应动力学

基于PuH_2分子基态(X~7A_1)的分析势能函数，用准经典的Monte-Carlo轨线法 对Pu(~7Fg)+H_2(X~1∑_g~+，0，0)的分子反应动力学过程进行了计算。结果表明 ：Pu(~7F_g)与H_2(X~1∑_g~+，0，0)碰撞是弹性碰撞。     

A comparative study of several HPLC methods for determining free amino acid profiles in honey

A study of the viability of three derivatizing reagents for obtaining amino acid profiles in honey through high performance liquid chromatography (HPLC) is presented. A method using diode array detection based on a reaction with diethyl ethoxymethylene malonate (DEMM) and two other methods using fluorescence detection based on derivatization with fluorenylmethyl chloroformate (FMOC-Cl) and 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate (AQC) have been developed. The three methods yield detection limits close to the ppb level, but vary in relation to other analytical characteristics. The use of methyl chloroformate derivatives allows the profile to be obtained with the greatest sensitivity within a short time frame. On applying such methods to honey samples of diverse botanical origin, we observe that the proline values obtained are always lower than those found using the official spectrophotometric method, thereby underlining the advisability of using HPLC methods to reduce uncertainty in these results.     

来曲唑的合成、表征及晶体研究

合成了抗癌药物4,4′-(1H-1,2,4-三唑-1-亚甲基)-双-甲苯基氰,测定了其IR, NMR和单晶结构,晶体C17H11N5属单斜晶系,空间群P21/n,晶胞参数:a=0.70300(14) nm, b=1.6170(3) nm, c=1.3360(3) nm, β=104.80(3)°, Z=4.结构解析最终一致性因子R1=0.0897.分子间通过氢键和范德华力形成超分子结构.     

芳亚甲基丙二腈、芳亚甲基氰乙酰胺的固相合成

芳醛和丙二腈、氰乙酰胺在NH4Ac催化下经固相反应高产率的得到芳亚甲基丙 二腈和芳亚甲基氰乙酰胺。     

Application of a mercuric iodide detector for the exploration and exploitation of niobium deposits in remote areas

The comparison of an ambient temperature mercuric iodide spectrometer (HgI₂) with a conventional cooled Si(Li) spectrometer is presented for the determination of niobium in Venezuelan laterites in the laboratory. The energy resolution of the HgI₂ spectrometer was only about 590 eV (FWHM) at 5.9 keV compared to about 150 eV for the conventional Si(Li) spectrometer. The efficiency was about 5 times lower in the region of the Nb_K peak as compared to the Si(Li) detector. Even though its energy resolution and efficiency is much poorer than the conventional Si(Li), the results it produced for the determination of niobium were acceptable for use in the exploration and exploitation of a niobium-rich deposit such as Cerro Impacto, Estado Bolívar, Venezuela.     

钯催化α-炔醇立体专一合成α-（Z）-氯亚甲基-β-内酯

首次在一氧化碳存在下，以仲丁醇和苯为混合反应溶剂，氯化钯和氯化铜为催 化体系催化α-炔醇羰基化，立体专一合成α-（Z）-氯亚甲基-β-内酯环。     

meso-四(对烷氧苯基)卟啉金属配合物的合成和性能研究(IV)

合成了系列卟啉乙酸合锰配合物9个,其中6个为未见文献报道的新化合物.用UV,1HNMR,IR,MS,元素分析等表征确证了配合物的结构,总结了锰与卟啉类配体配合的IR,UV,1HNMR判据.采用差示扫描量热法(DSC)和偏光显微镜(PM)研究了该系列配合物的液晶性能,发现8个配合物具有液晶性.考察了烷氧基链长、配位金属离子和分子空间结构对液晶性能的影响.