HPLC法测定依折麦布中有关物质

建立依折麦布有关物质的测定方法。色谱柱采用十八烷基硅烷键合相硅胶为填充剂,流动相A为磷酸盐缓冲溶液（取磷酸二氢钠一水合物2.76 g,溶解于1 000 mL纯水中,用稀氢氧化钠溶液调节pH至5.0）-乙腈（80∶20）;流动相B为乙腈-水（85∶15）。检测波长230 nm,流速1.2 mL/min。各种破坏性样品的分离度符合规定。依折麦布的相关分离度均大于1.5,符合要求。本方法迅速,准确,灵敏度高,专属性强,可用于本品有关物质的测定。     

高效液相色谱法测定维生素C泡腾片有关物质含量

目的:建立维生素C泡腾片中有关物质含量的测定方法。方法:采用高效液相色谱法,色谱柱为PerfectChrom 100 C18(250 mm×4.6 mm,5μm);流动相为磷酸盐缓冲溶液(pH2.50±0.05);流速:0.8mL/min;进样量:20μL;检测波长为245 nm。结果:维生素C质量浓度在4.0~16.0μg/mL范围内,进样量在0.0618~0.5562μg范围内与峰面积线性关系良好(r=0.9990)。结论:该方法简便准确,稳定性好,可用于维生素C泡腾片中有关物质的含量测定。     

普拉格雷含量及有关物质的测定

采用HPLC法测定了普拉格雷原料药含量和有关物质。色谱条件如下:色谱柱为C18柱(150mm×4.6mm,5μm),柱温30℃,流动相为乙腈-磷酸盐缓冲溶液(pH值5.0)(50∶50,体积比),流速1.0mL·min-1,检测波长219nm,进样量10μL。结果表明:普拉格雷在0.5~3.0μg·mL-1范围内,线性关系良好,平均加样回收率为99.95%(n=9)。此法操作简便、快速、灵敏、准确,样品处理简便易行,可用于测定普拉格雷原料药含量和有关物质。     

Characterization of spectral responses of humic substances upon UV irradiation using two-dimensional correlation spectroscopy

The spectral responses of a leaf litter derived humic substance (LLHS) and Suwannee River fulvic acid (SRFA) upon ultraviolet (UV) A irradiation were characterized using two-dimensional correlation spectroscopy (2D-COS) based on the absorption and the synchronous fluorescence spectra at different irradiation times. A 12 day irradiation on the humic substances (HS) resulted in higher reduction of the absorbance relative to the dissolved organic carbon concentration, suggesting that aromatic chromophores were preferentially oxidized and/or non UV-absorbing compounds were generated by the photobleaching. Synchronous fluorescence spectra revealed the preferential removal of fulvic-like and humic-like fluorophores and delayed response of protein-like fluorescence upon the irradiation. The spectral features at long wavelengths (>430 nm) appear to be affected by intra-molecular interactions of the individual chromophores associated with shorter wavelengths. Absorption-based 2D-COS demonstrated that there are three types of absorption bands for the two HS, which changed sequentially in the order of 290-400 nm → 200-250 nm → 250-290 nm. In addition, two or three distinctive fluorescence bands in response to the irradiation were identified from 2D-COS. The sequential orders and the associated wavelength bands were possibly explained by the irradiation wavelengths and the differences between direct and indirect photochemical reactions. The interpretation of the 2D-COS results was very consistent with the kinetic rate constants individually calculated at several discrete wavelengths. Our study demonstrated that 2D-COS could be used as a powerful tool in identifying distinctive bands of HS that have dissimilar behavior and the associated sequential orders by visualizing the spectral changes at continuous wavelengths.     

Fate of coagulant species and conformational effects during the aggregation of a model of a humic substance with Al13 polycations

A model of a humic substance (MHS) obtained from auto-oxidation of catechol and glycine, was aggregated at pH 6 and 8 with Al(13) polycations. The fate of Al(13) coagulant species upon association with MHS functional groups was studied using solid state (27)Al Magic-angle spinning (MAS) NMR and CP-MAS (13)C NMR. Electrophoretic measurements and steady-state fluorescence spectroscopy with pyrene as a fluoroprobe, were combined to investigate structural re-organization of humic material with aluminum concentration. MAS (27)Al NMR revealed that the coagulant species are Al(13) polycations or oligomers of Al(13) units at both pHs. CP MAS (13)C spectra indicated that, at low Al concentration, hydrolyzed aluminum species bind selectively to carboxylic groups at pH 6 and to phenolic moieties at pH 8. At higher coagulant concentrations, the remaining functional groups also interact with hydrolyzed Al to yield similar CP MAS (13)C spectra in the optimum concentration range. Negative values of electrophoretic mobility were obtained at optimum coagulant concentrations even though an overall charge balance was achieved between MHS anionic charge and Al(13) cationic charge at pH 6. The polarity-sensitive fluorescence of pyrene revealed that the interaction of Al(13) coagulant species with MHS functional groups induces the formation of intramolecular hydrophobic microenvironments. Such structural changes were reversed upon further addition of Al(13) polycations.     

Composition of a protein-like fluorophore of dissolved organic matter in coastal wetland and estuarine ecosystems

This study demonstrates the compositional heterogeneity of a protein-like fluorescence emission signal (T-peak; excitation/emission maximum at 280/325 nm) of dissolved organic matter (DOM) samples collected from subtropical river and estuarine environments. Natural water samples were collected from the Florida Coastal Everglades ecosystem. The samples were ultrafiltered and excitation-emission fluorescence matrices were obtained. The T-peak intensity correlated positively with N concentration of the ultrafiltered DOM solution (UDON), although, the low correlation coefficient (r(2)=0.140, p<0.05) suggested the coexistence of proteins with other classes of compounds in the T-peak. As such, the T-peak was unbundled on size exclusion chromatography. The elution curves showed that the T-peak was composed of two compounds with distinct molecular weights (MW) with nominal MWs of about >5 x 10(4) (T(1)) and approximately 7.6 x 10(3) (T(2)) and with varying relative abundance among samples. The T(1)-peak intensity correlated strongly with [UDON] (r(2)=0.516, p<0.001), while T(2)-peak did not, which suggested that the T-peak is composed of a mixture of compounds with different chemical structures and ecological roles, namely proteinaceous materials and presumably phenolic moieties in humic-like substances. Natural source of the latter may include polyphenols leached from senescent plant materials, which are important precursors of humic substances. This idea is supported by the fact that polyphenols, such as gallic acid, an important constituent of hydrolysable tannins, and condensed tannins extracted from red mangrove (Rhizophora mangle) leaves exhibited the fluorescence peak in the close vicinity of the T-peak (260/346 and 275/313 nm, respectively). Based on this study the application of the T-peak as a proxy for [DON] in natural waters may have limitations in coastal zones with significant terrestrial DOM input.     

Influence of loosely bound extracellular polymeric substances (EPS) on the flocculation, sedimentation and dewaterability of activated sludge

Laboratory experiments on the activated sludge (AS) process were carried out to investigate the influence of microbial extracellular polymeric substances (EPS), including loosely bound EPS (LB-EPS) and tightly bound EPS (TB-EPS), on biomass flocculation, sludge settlement and dewaterability. The heat EPS extraction method was modified to include a mild step and a harsh step for extracting the LB-EPS and TB-EPS, respectively, from the sludge suspension. Six lab-scale AS reactors were used to grow AS with different carbon sources of glucose and sodium acetate, and different sludge retention times (SRTs) of 5, 10 and 20 days. The variation in the bioreactor condition produced sludge with different abundances of EPS and different flocculation and separation characteristics. The sludge that was fed on glucose had more EPS than the sludge that was fed on acetate. For any of the feeding substrates, the sludge had a nearly consistent TB-EPS value regardless of the SRT, and an LB-EPS content that decreased with the SRT. The acetate-fed sludge performed better than the glucose-fed sludge in terms of bioflocculation, sludge sedimentation and compression, and sludge dewaterability. The sludge flocculation and separation improved considerably as the SRT lengthened. The results demonstrate that the LB-EPS had a negative effect on bioflocculation and sludge-water separation. The parameters for the performance of sludge-water separation were much more closely correlated with the amount of LB-EPS than with the amount of TB-EPS. It is argued that although EPS is essential to sludge floc formation, excessive EPS in the form of LB-EPS could weaken cell attachment and the floc structure, resulting in poor bioflocculation, greater cell erosion and retarded sludge-water separation.     

广州帽峰山1号别墅

以帽峰山1号别墅为主,通过规划设计、建筑设计、室内设计、园林设计等多方面阐述岭南建筑在帽峰山的再发展。     

高分子建筑防水材料工业生产中的卫生防护(上)

对高分子建筑防水材料工业生产中的卫生危害及卫生防护进行了概貌性地评述。     

Polymeric compounds in activated sludge supernatant -- Characterisation and retention mechanisms at a full-scale municipal membrane bioreactor

In this study, for the first time a full-scale membrane bioreactor (MBR) was investigated with focus on organic compounds in activated sludge over a period of approximately 2 years. Soluble extracellular polymeric substances (EPS) in the sludge supernatant and permeate as well as bound EPS extracted from fouled membranes were determined photospectrometrically and revealed a typical composition of three main components in the order metals>humic acids>carbohydrates>proteins. Results showed an important influence on membrane fouling by soluble humic substances and carbohydrates in complexes with metal cations. It was found that Fe(2+) and Fe(3+) play a decisive role in natural organic matter (NOM) complexation and subsequent membrane blockage. The determination of molar mass distribution in supernatant and permeate by size exclusion chromatography (SEC) revealed a significant retention of macromolecular compounds by the porous membranes in the range of 10-50%.