[Characteristics and Source Apportionment of Volatile Organic Compounds (VOCs) in the Automobile Industrial Park of Shanghai].

Volatile organic compounds (VOCs) are important precursors of ozone and fine particulate matter, and have attracted more and more research attention. There are few long-term observational studies of VOCs in automobile industry parks. From January 1 to December 31,2019, 79 kinds of VOCs were quantitatively detected by on-line gas chromatograph in an automobile industrial park in Shanghai. The composition, seasonal variation, and daily variation of VOCs were analyzed. The chemical reactivity of the atmosphere was estimated using the maximum incremental reactivity (MIR) and·OH radical loss rate. The sources of VOCs were analyzed using specific pollutant ratios and factor analysis. The results showed that the total VOCs concentration was 26.53×10-9, with alkanes, alkenes, aromatics, halo hydrocarbon, and alkynes accounting for 50.2%, 9.8%, 22.4%, 10.8%, and 6.8%, respectively. There was an obviously seasonal variation in VOCs concentrations, with the maximum occurring in winter and the minimum in summer. Ozone formation potential (OFP) was 73.2×10-9, of which alkanes accounted for 14.7%, alkenes 35.9%, and aromatics 45.2%. The·OH radical loss rate was 165.3 s-1, of which alkenes accounted for 30.4% and aromatics 48.9%. The components with the highest contributions to chemical reaction activity were m/p-xylene, ethylene, propylene, toluene, and o-xylene. By estimating toluene/benzene ratios (T/B) and ethane/acetylene ratios (E/E), the air mass at the observation site was fresh, site was close to the pollution source. The main sources of VOCs were gasoline exhaust emissions (19.4%), solvent use (30.8%), combustion processes (11.0%), diesel use (8.9%), and liquefied petroleum gas use (4.5%).

Determination of trace bismuth by flow injection-hydride generation collection-atomic absorption spectrometry.

Bismuth hydride gas was collected on-line and determined via a new flow injection-hydride generation collection-flame atomic absorption spectrometry system. The performance of the gas-liquid separator, hydride gas collection time, acidity of the sample solution, NaBH(4) concentration, and the effects of concomitant interferents were investigated to optimize the conditions of this new method. Interferences from concomitant elements were investigated, and recoveries of 94.7-105.3% for 10 ng mL(-1) Bi were obtained after the addition of 0.2% ascorbic acid-thiourea masking reagents. The sensitivity of this new method was one order of magnitude higher than the continuous flow-hydride generation-flame atomic absorption method with a detection limit of 0.25 ng mL(-1) and a precision of 2.3%. The method was evaluated by determining trace bismuth in standard biological reference material human hair GBW07601, and the results were consistent with the certified value. The proposed method was then employed to determine trace bismuth in ten colored gelatin samples; recoveries of 94.2-105.8% were obtained.

Biochemical Properties of Bound-Ca(2+) in Fibrinolytic Principle (FP) Separated from Agkistrodon acutus Venom.

It has been determined that each FP molecular contains one Ca(2+)-binding site. By the use of fluorescence probe Tb(3+), the distance between Tb(3+) and tryptophan (Trp) residue was obtained to be 0.375. Tb(3+) ion is coordinated with FP more strongly than Ca(2+) ion, and can bind to FP and replace the Ca(2+) ion in FP completely.

Fluorescence Analysis of the Fibrinolytic Principle (FP) from Agkistrodon acutus Venom.

The conformation and the properties of the fibrinolytic principle (FP) from Agkistrodon acutus venom were studied by chemical modification and fluorescence spectroscopy. Results showed that there are more than one tryptophan (Trp) residue in the FP molecule and they are located in the more hydrophobic core, could be quenched by acrylamide (Acr), a polarized quencher without electric charge. The collisional quenching constants of FP at different concentrations of Acr were calculated in terms of Stern-Volmer equation, and the fraction of the Trp quenched was obtained by the modified Stern-Volmer equation as 83%.