流动注射分光光度法测定水体总磷

提出了一种单通道紫外消解流动注射比色分析法，能快速测定水样中总磷。实验采用了微量恒流混合泵、新型的细长型高灵敏度流通池及紫外消解器、液流分配阀、恒流瓶等FIA装置，并使用工业编程控制器和智能触摸屏进行控制和计算，使操作更为方便。此法分析时间短，测量范围宽，精度高，适合于各种水体的测定。     

Synthesis,Conformation, and Metabolism of a Selenium Bilirubin

Summary. A symmetrical C(10)-selena-bilirubin analog, 8,12-bis(2-carboxyethyl)-7,13-dimethyl-2,3,17,18-tetraethyl-10-selenabiladiene-ac-1,19(21H,24H)-dione was synthesized from 8-(2-carboxyethyl)-2,3-diethyl-7-methyl-(10H)-dipyrrin-1-one in one step by reaction with diselenyl dichloride. The selena-rubin exhibited UV-vis and NMR spectroscopic properties similar to those of the parent mesobilirubin, and like bilirubin and mesobilirubin, it adopts an intramolecularly hydrogen-bonded conformation, shaped like a ridge-tile but with a steeper pitch. The longer C–Se bond lengths (2.2Å) and smaller bond angles at C–Se–C (88°), as compared to C–CH₂–C (1.5Å, 106°), lead to an interplanar angle between the two dipyrrinones of only 72°, which is considerably less than that of bilirubin (100°) and close to that (74°) of its 10-thia-rubin analog. Despite the conformational distortion, the sensitivity of Se toward oxidation and the typically weak C–Se bond, the selena-rubin is metabolized in normal rats, like bilirubin, to acyl glucuronides, which are secreted into bile. In mutant (Gunn) rats lacking bilirubin glucuronosyl transferase (UGT1A1), glucuronide or other metabolites of the selena-rubin were not detected in bile, demonstrating the importance of hepatic glucuronidation for its biliary excretion.     

Bibliometric Analysis of the <Emphasis Type="Italic">Journal of Structural Chemistry</Emphasis>

Bibliometric analysis has been carried out for the Journal of Structural Chemistry (JSC) published since 1960 by the Siberian Branch of the Russian Academy of Sciences. All JSC publications which appeared between 1960 and 2002 have been chosen online from the Chemical Abstracts and Science Citation Index databases of the STN International net and analyzed according to topics, authors, affiliations, and other criteria. JSC authors and publications with the largest numbers of citations have been identified. The impact factor has been determined for JSC 2002.Original Russian Text Copyright © 2004 by V. M. Buznik, I. V. Zibareva, V. N. Piottukh-Peletskii, and N. I. Sorokin__________Translated from Zhurnal Strukturnoi Khimii, Vol. 45, No. 6, pp. 1142–1153, November–December, 2004.     

Fluorescence Analysis in Microarray Technology

Fluorescence has been the preferred choice for data quantification in biomedical microarray formats since their earliest days. As much as the formats have grown and evolved over the years, the methods in optical analysis have become ever more sophisticated and complex in order to produce more and better output. This review will provide an insight into the most common methods and the state-of-the-art of all areas in microarray fluorescence analysis. Starting with an overview on microarray formats with a focus on their demands on the readout, the most common and useful organic fluorescent stains are discussed before proceeding on to other approaches; the use of semiconductor nanocrystals (quantum dots), polymer and silica nanoparticles and fluorescent proteins. Ways to enhance the intrinsically low signal on biochips have become increasingly important as they offer a sound approach towards the detection of low concentration sample content. The three main categories are presented: amplification using DNA, enzymes, and dendrimers. As much diversity as on the microarrays themselves can be found at the detection device. Standard optical microarray detectors, and non-standard methods using fluorescence anisotropy, fluorescence lifetime imaging (FLIM) and fluorescence resonance energy transfer (FRET), and their advantages and disadvantages are discussed.     

Synthese und Konfigurationszuordnung von potentiell antimikrobiellen 5,6-Dihydroxyisobenzofuranonen

Summary Oxidation of isobenzofuranone1 yielded in a diastereoselective reaction epoxide2. Acidolysis of2 resulted in a mixture oftrans-glycols6 a (88%) and7 a (4%), which were separated by crystallization. The relative configuration of6 a and7 a at the chiral centers 3 a, 5, 6, and 7 a was determined by¹H-NMR-spectroscopy and X-ray analysis of O-acetylated and 7 a-methylated derivatives.

     

Developing a sequential injection-square wave voltammetry (SI-SWV) method for determination of atrazine using a hanging mercury drop electrode

This paper describes the development of a sequential injection analysis method to automate the determination of atrazine by square wave voltammetry exploiting the concept of monosegmented flow analysis to perform in-line sample conditioning and standard addition. To perform these tasks, an 800 μL monosegment is formed, composed by 400 μL of sample and 400 μL of buffer/standard solution. To obtain an efficient homogenization, the sample solution is divided in five zones intercalated by four zones of the Britton-Robinson buffer (pH 2.0) in presence of appropriate concentration of NaNO₃ and varying atrazine standard concentrations. This mixture zone is isolated from the carrier solution by two 100 μL air bubbles. After homogenization in an auxiliary reaction coil the mixture zone is injected toward the flow cell, which is adapted to the capillary of a hanging drop mercury electrode, at a flow rate of 50 μL s⁻¹. After a suitable delay time, the potential is scanned from −0.5 to −1.2 V versus Ag/AgCl using a frequency of 300 Hz and pulse height of 25 mV. The linear dynamic range is observed for atrazine concentrations between 1.16 × 10⁻⁷ and 2.32 × 10⁻⁶ mol L⁻¹, obeying the linear equation i_p = (−6.91 ± 0.07) × 10⁸[atrazine] + (4 ± 8), with r² = 0.9996, for which the slope is given in nA L mol⁻¹. The detection and quantification limits of the method are 2.1 × 10⁻⁸ and 7.0 × 10⁻⁸ mol L⁻¹, respectively. The sampling frequency is 37 h⁻¹, when the standard addition protocol is followed. This frequency can be increased to 42 h⁻¹ if the protocol to obtain in-line calibration curve is used for quantification. The method was applied for determination of atrazine in spiked river water samples and its accuracy was evaluated by comparison with the batch standard addition approach, which revealed that there is no evidence of statistically significant differences between the two methods.     

Selenium speciation in foods: Preliminary results on potatoes

The present paper deals with the speciation of selenium in potatoes (enriched or not in selenium). The study was carried out by using differential pulse cathodic stripping voltammetry (DPCSV) for quantifying selenium. Results obtained provide evidence that the selenium content in the protein fraction is rather independent from the selenium added to the plants during their growth. On the contrary, the amount of Se in the non-protein fraction (water and starch) in Se-enriched sample is significantly higher than in non-enriched one, suggesting that it is the main selenium-storing site. In this fraction the Se(VI)/Se(IV) ratio seems independent from selenium application but it may be related to the redox conditions. The accumulation of selenium in the non-protein fraction is tentatively ascribed to the “Se–starch interaction” that should be able to modulate both the Se absorption into proteins and, possibly, its toxic effect for the plant itself.     

Use of short columns and high flow rates for rapid gradient reversed-phase chromatography

Summary Rapid analyses were performed using reversed-phase liquid chromatography with short (20–100 mm) columns swept by fast yet shallow gradients, and the results compared with those obtained with 150 mm columns and slow gradients. The resolution losses incurred with shorter columns were minimised by employing elevated flow rates, to ensure that comparable mean retention factors were experienced by individual analytes during gradients run on different columns. This conserves gradient steepness. High quality performance was obtained with turn-around times of 5–10 minutes. An overall 5-fold enhancement in the rate of information generation was obtained. The relevance of instrumental parameters and of column and packing dimensions, upon the potential for improved performance is discussed. Some implications for the rapidly developing technique of capillary electrochromatography are briefly indicated.