Development of a sensitive fluorescent derivatization reagent 1,2-benzo-3,4-dihydrocarbazole-9-ethyl chloroformate (BCEOC) and its application for determination of amino acids from seeds and bryophyte plants using high-performance liquid chromatography with fluorescence detection and identification with electrospray ionization mass spectrometry

A pre-column derivatization method for the sensitive determination of amino acids and peptides using the tagging reagent 1,2-benzo-3,4dihydrocarbazole-9-ethyl chloroformate (BCEOC) followed by high-performance liquid chromatography with fluorescence detection has been developed. Identification of derivatives was carried out by liquid chromatography/electrospray ionization mass spectrometry (LC/ESI-MS/MS). The chromophore of 2-(9-carbazole)-ethyl chloroformate (CEOC) reagent was replaced by 1,2-benzo-3,4-dihydrocarbazole functional group, which resulted in a sensitive fluorescence derivatizing reagent BCEOC. BCEOC can easily and quickly label peptides and amino acids. Derivatives are stable enough to be efficiently analyzed by high-performance liquid chromatography. The derivatives showed an intense protonated molecular ion corresponding m/z (M + H)(+) under electrospray ionization (ESI) positive-ion mode with an exception being Tyr detected at negative mode. The collision-induced dissociation of protonated molecular ion formed a product at m/z 246.2 corresponding to the cleavage of C-O bond of BCEOC molecule. Studies on derivatization demonstrate excellent derivative yields over the pH 9.0-10.0. Maximal yields close to 100% are observed with a 3-4-fold molar reagent excess. Derivatives exhibit strong fluorescence and extracted detzvatization solution with n-hexane/ethyl acetate (10:1, v/v) allows for the direct injection with no significant interference from the major fluorescent reagent degradation by-products, such as 1,2-benzo-3,4-dihydrocarbazole-9-ethanol (BDC-OH) (a major by-product), mono- 1,2-benzo-3,4-dihydrocarbazole-9-ethyl carbonate (BCEOC-OH) and bis-(1,2-benzo-3,4-dihydrocarbazole-9-ethyl) carbonate (BCEOC)(2). In addition, the detection responses for BCEOC derivatives are compared to those obtained with previously synthesized 2-(9-carbazole)-ethyl chloroformate (CEOC) in our laboratory. The ratios AC(BCEOC)/AC(CEOC) = 2.05-6.51 for fluorescence responses are observed (here, AC is relative fluorescence response). Separation of the derivatized peptides and amino acids had been optimized on Hypersil BDS C-18 column. Detection limits were calculated from 1.0 pmol injection at a signal-to-noise ratio of 3, and were 6.3 (Lys)-177.6 (His) fmol. The mean interday accuracy ranged from 92 to 106% for fluorescence detection with mean %CV < 7.5. The mean interday precision for all standards was < 10% of the expected concentration. Excellent linear responses were observed with coefficients of > 0.9999. Good compositional data could be obtained from the analysis of derivatized protein hydrolysates containing as little as 50.5 ng of sample. Therefore, the facile BCEOC derivatization coupled with mass spectrometry allowed the development of a highly sensitive and specific method for the quantitative analysis of trace levels of amino acids and peptides from biological and natural environmental samples. (c) 2005 Elsevier B.V. All rights reserved.

流体地球化学：成因、流动和流体-岩石相互作用及塔里木盆地实例研究

Geofluid in sedimentary basins is related to petroleum generation, migration, accumulation and preservation, and is a topic of geological frontier. By integrating the multi-discipline methods of petroleum geochemistry, sedimentology, hydrogeology, petroleum geology and experimental geochemistry, the thesis has carried out experiments of microcline dissolution in solutions with organic acids, crude oil, brines with high total dissolved solids (TDS), and has dealt with Al distribution between the crude oil and the brines after the experiments. Cases for study includes Central Tarim, Hetianhe Gas Field and Kucha forland basin with data containing fluid chemistry and isotopic compositions, thin sections of sandstones and carbonates, homogenization temperatures and salinities of fluid inclusions, isotopic compositions of bulk rock and autigenic minerals. The aims are to elucidate fluid origin and flow in the three areas, effect of hydrocarbon emplacement on diagenesis, and to show occurrence of microbe-mediated, and thermochemical sulfate reduction in the Tarim Basin. Microcline dissolution experiments show that after 100 hour, part of the dissolved Al distributes in the crude oil, and the Al concentrations in the crude oil rise when organic acids are added. The result can be used to explain that most oilfield waters in the Tarim Basin are characterized by less than 3mg/L Al. Crude oil added to the solutions can enhance microcline dissolution, which is also observed in the case - Silurian sandstones with early crude oil emplacement in the Central Tarim. Al and Si have higher concentrations in the experiments of oxalic acid than of acetic acid under the same pH conditions, suggesting that there exist Al-oxalate and Si-oxalate complexes. Presence of acetate can enhance the activity of Ca and Al, but Al concentrations have not been increased significantly due to formation of small Al-acetate complex during the experiments. Relationships between δD and δ~(18)O in conjunction with chemistry of oilfield waters show that the waters are evaporated connate waters, which subsequently mixed with meteoric water, and were influenced by water-rock interactions such as salt dissolution, dolomitization of calcite, albitization of feldspar. In the Hetianhe Gas Field where salt dissolution took place, δD and δ~(18)O values can be used to trace nicely meteoric water recharge area and flow direction, but TDS can not. Part of the waters have high TDS but very light δD and δ~(18)O. When combined with paleo-topography, or fluid potentials, meteoric water is suggested to flow eastward in the Hetianhe Gas Field, which is the same with the Central Tarim. Whist in the Kuche forland basin, meteoric water may have permeated Cambrian-Ordovician strata. Relationship between ~(87)Sr/~(86)Sr and 1/Sr can be used to indicate migration and mixing of brines from carbonate strata (low ~(87)Sr/~(86)Sr ratio but high Sr content), clastic strata (high ~(87)Sr/~(86)Sr ratio but low Sr content) and crystalline basement (high ~(87)Sr/~(86)Sr ratio and heavy δ~(18)O value). Using this approach, it can be found that ~(87)Sr-depleted brine from Ordovician carbonates have migrated up to and mixed with ~(87)Sr-enriched waters from Silurian and Carboniferous sandstones, and that Silurian brines have mixed with meteoric water. In the Kuche forland basin, brines from the Cambrian and Ordovician carbonates have higher ~(87)Sr/~(86)Sr ratios than those from the overlying sandstones, when combined with chemistry, δ~(15)N and ~3He/~4He ratios of the coexisting natural gases, suggesting that the brines were derived from the basement. There exists some debate on the effect of hydrocarbon emplacement on mineral diagenesis. Case-study from Silurian sandstones in the Central Tarim show that quartz has kept overgrowing secondarily when oil saturation was decreased by meteoric water flushing subsequently to hydrocarbon emplacement. Silicon precipitates on the water-wet quartz surface, leading to decreased Si concentration close to the surface. A Si grads can result in Si diffusion, which supplies Si for quartz overgrowth. Hydrocarbon oxidation-sulfate reduction is an important type of organic-inorganic interaction. Not only can it make secondary alteration of hydrocarbons, but generate H_2S and CO_2 gases which can improve reservoir property. Thermochemical sulfate reduction took place at the temperatures more than 125 ℃ to 140 ℃ in the Cambrian-Ordovician carbonates, the products - H_2S and CO_2 gases migrated up to the Silurian, and precipitated as pyrite and calcite, respectively. The pyrite has an average δ~(34)S value close to those of Ordovician seawater and anhydrite, and calcite has δ~(13)C value as low as -21.5‰. In the Hetianhe Gas Field, sulfate reduction bacteria carried by meteoric water flowing eastward may have preferentially depleted ~(12)C of light hydrocarbon gases, and results in heavier δ~(13)C values of the residual hydrocarbon gases and higher molar CO_2 in the natural gases in the west than in the east. Coexisting pyrite has δ~(34)S values as low as -24.9‰.

Enhancement of molar heat capacity of nanostructured Al2O3

The nanosized alumina prepared by the hydrolysis method with an average particle size of 20 nm was characterized by X-ray diffraction. The heat capacity measurements of the prepared sample were carried out using an adiabatic calorimeter in the temperature range from 78 to 370 K. Enhancement of heat capacity was observed in the nanostructured materials as the heat capacity data were compared with those of the corresponding coarse-grained materials. The enhanced heat capacity was discussed on the basis of experiments. Differential scanning calorimetry and thermogravimetry were used to determine the thermal stability of the nanostructured alumina.

Preparation of titania-based catalysts for formaldehyde photocatalytic oxidation from TiCl4 by the sol-gel method

Titania sols were prepared by acid hydrolysis of a TiCl4 precursor instead of titanium alkoxides. The effect of acid concentration on the particle size and stability of sol was investigated. Stable titania sols with mean particle size of 14 nm could be obtained when the H+/Ti molar ratio was 0.5. The titania sols were modified with Pt, SiO2, ZrO2, WO3 and MoO3 to prepare a series of modified catalysts, which were used for the photocatalytic oxidation of formaldehyde at 37 degreesC. They showed different photocatalytic activities due to the influence of the additives. Comparing with pure TiO2, the addition of silica or zirconia increased the photocatalytic activity, while the addition of Pt and MoO3 decreased the activity, and the addition Of WO3 had little effect on the activity. It is of great significance that the conversion of formaldehyde was increased up to 94% over the SiO2-TiO2 catalyst. The increased activity was partly due to higher surface area and porosity or smaller crystallite size. A comparison of our catalyst compositions with the literature in this field suggested that the difference in activity due to the addition of a second metal oxide maybe caused by the surface chemistry of the catalysts, particularly the acidity. (C) 2001 Elsevier Science B.V. All rights reserved.