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961.
Pharmaceuticals are emerging contaminants in surface water and they must be measured to follow their effects on the aquatic environment. We developed a solid-phase extraction and liquid chromatography-electrospray ionization tandem mass spectrometry (SPE-LC-ESI-MS/MS) method for the determination of twenty-six pharmaceutical compounds - which belong to antihypertensive and anti-ulcer agents - from surface water samples. The selection of pharmaceuticals was based on usage frequency in Hungary. During method development Oasis HLB, SampliQ Polymer SCX and Si-SCX SPE cartridges were tested. As LC eluent ammonium formate, ammonium acetate buffers at pH 3 and 5 were investigated and for quantitation both matrix-matched and internal standard calibration was used. For matrix effect assessment post-extraction spike method was applied which can separate the extraction efficiency from ion suppression for better determination of recovery. Method detection limits (MDLs) varied between 0.2 and 10 ng/L. Precision of the method, calculated as relative standard deviation (RSD), ranged from 0.2 to 14.6% and from 1.2 to 22.4% for intra- and inter-day analysis, respectively. The method was applied to analyze Danube water samples. Measured average concentrations varied between 2 and 39 ng/L for eleven compounds and another one could be detected under LOQ. 相似文献
962.
This paper reports the use of polyurethane foam (PUF) as solid support for diffuse reflectance spectrophotometric determination of Malachite Green (MG), a well known cationic dye used as biocide in the aquaculture industry, using sodium dodecylsulfate (SDS) as a counter ion. The method was based on the formation of an ionic-pair between the dye and the anionic surfactant SDS, which was sorbed onto PUF surface, where the diffuse reflectance was measured at 635 nm. Several parameters that could affect the performance of the system were evaluated. As expected, the SDS concentration presented strong influence on the analytical signal because the PUF was able to retain only the ionic-pair. The pH influenced the analytical signal, which was more intense in the acidic/neutral range, while the ionic strength only influenced the kinetic of the MG (as MG-SDS ionic-pair) sorption. The methodology was employed in the determination of MG in river waters and a recovery test was performed to test the accuracy of the procedure. Recovery percentages between 98.7 and 107% were observed when 60 or 80 μg L(-1) of MG were added to the samples. 相似文献
963.
Victório CP Leal-Costa MV Tavares ES Kuster RM Lage CL 《Photochemistry and photobiology》2011,87(3):685-689
Phyllanthus tenellus is widely used for its antiviral, analgesic and hepatoprotective properties. Although the production of several chemical classes of secondary metabolites is influenced by UV radiation, particularly phenolic compounds, we also know that UV radiation can result in anatomical and developmental damage. However, the morphological, anatomical and phytochemical changes in response to UV-A exposure are generally understudied in the Phyllanthaceae. Therefore, we evaluated the effects of UV-A radiation on plant development and leaf anatomy, as well as the production of secondary metabolites and the contents of carotenoids and chlorophylls a and b, in P. tenellus. To accomplish this, in vitro cultures of P. tenellus were maintained for 60 days under white light (WL) and WL plus UV-A radiation. Results showed different phenotypic responses under additional UV-A, such as high phenolic metabolite production, increasing dimensions of abaxial epidermis and thickness of palisade parenchyma. Compared to plants cultured under WL, UV-A radiation caused damage to plant morphogenesis, including a reduced number of branches and shoots, consequently reducing the rate of proliferation. On the other hand, geraniin, ellagic acid and carotenoid contents increased after UV-A exposure, indicating that this light source is an important resource for inducing phenolic compounds. 相似文献
964.
Kerry J. GoodworthAnne-Cécile Hervé Evangelos StavropoulosGwénaelle Hervé Isabel Casades Alison M. HillGordon G. Weingarten Ricardo E. TasconM. Joseph Colston Helen C. Hailes 《Tetrahedron》2011,67(2):373-382
A series of large-ringed calix[6,7,8]arene analogues have been synthesised and their affect against Mycobacterium tuberculosis in vivo established. In general, when p-phenylcalixarenes and tert-butylcalixarenes were not functionalised at the lower rim, low biological activities were observed. However on going from partially to fully lower rim pegylated calixarenes the anti-mycobacterial properties improved. The addition of cyanopropoxy groups at the lower rim gave rise to low activities, whereas the addition of acetate moieties interestingly had pro-TB effects. Two upper rim sulfonated calixarenes showed promising properties. In the course of this work, a high yielding procedure to synthesise p-phenylcalix[7]arene was also established. 相似文献
965.
Interest in the synthesis of the C(23)-C(40) fragment 2 of tetrafibricin prompted us to develop a new method for the synthesis of 1,5-syn-(E)-diols. Toward this end, the kinetically controlled hydroboration of allenes 6, 33, ent-39, 42, and 45 with the Soderquist borane 25R were studied. Tetrabutylammonium allenyltrifluoroborate 45 gave superior results and was utilized in a double allylboration sequence with two different aldehydes to provide the targeted 1,5-syn-(E)-diols in generally high yields (72-98%), and with high enantioselectivity (>95% ee), diastereoselectivity (dr >20:1), and (E)/(Z) selectivity (>20:1). This new method was applied to the synthesis of the C(23)-C(40) fragment 2 of tetrafibricin. 相似文献
966.
967.
Željko Grahek Astrid Gojmerac Ivšić Nikolina Krljan Marijana Nodilo 《Journal of Radioanalytical and Nuclear Chemistry》2011,289(2):437-449
This paper describes the procedures of isolating strontium from wine and soil samples which enable creating of procedure for
rapid determination of 90Sr. The method of determination of 90Sr includes binding of Sr on the cationic exchanger IR-120 from the sample and simultaneous elution from the cation column
and binding on the Sr column, separation of Sr on Sr resin with HNO3 even in presence of alcohols and subsequent Cherenkov counting. Sr can be efficiently bind on Sr resin and separated from
the other elements with lower acid concentrations in the presence of a low portion of alcohol, or even from a wine sample
without the loss of Sr resin capacity. The binding strength of Sr on Sr resin decreases with the rising of HNO3 concentration (1–5 M) in the presence of 13% of ethanol or methanol, and with the rising of the alcohol portion in constant
concentration of HNO3. Application of cation exchanger for Sr binding in phase of sample preparation decreases Sr column loading and improve Sr
recovery. The method allows the determination of 90Sr activities in wine and soil sample lower than 10 mBq in reasonable time. 相似文献
968.
Lallana E Riguera R Fernandez-Megia E 《Angewandte Chemie (International ed. in English)》2011,50(38):8794-8804
The Cu(I)-catalyzed azide-alkyne cycloaddition (CuAAC) has been established as a powerful coupling technology for the conjugation of proteins, nucleic acids, and polysaccharides. Nevertheless, several shortcomings related to the presence of Cu, mainly oxidative degradation by reactive oxygen species and sample contamination by Cu, have been pointed out. This Minireview discusses key aspects found in the development of the efficient and benign functionalization of biomacromolecules through CuAAC, as well as the Cu-free strain-promoted azide-alkyne cycloaddition (SPAAC). 相似文献
969.
Regina Cisternas Eduardo Mu?oz Rodrigo Henr��quez Ricardo C��rdova Heike Kahlert Ulrich Hasse Fritz Scholz 《Journal of Solid State Electrochemistry》2011,15(11-12):2461-2468
Prussian blue (PB) can be deposited from colloidal solutions (5.4?×?10?3?molPB?L?1, 0.01?mol?L?1 KNO3) on glassy carbon, either by potential cycling or potentiostatically, provided that the deposition potential is more positive than ?0.2?V vs. Hg/Hg2Cl2. Depending on the deposition potential, the PB particles form either a single layer of Everitt??s salt, of PB, or multilayers of Berlin green. Also depending on the electrode potential, the deposition was accompanied by currents which were either only of capacitive nature, or represent the sum of capacitive and faradaic currents. The currents were always limited by the diffusion of the colloidal particles to the electrode surface, i.e., they obeyed the Cottrell equation. The PB layers were characterized by in situ atomic force microscopy. 相似文献
970.
Sen SS Hey J Eckhardt M Herbst-Irmer R Maedl E Mata RA Roesky HW Scheer M Stalke D 《Angewandte Chemie (International ed. in English)》2011,50(52):12510-12513
Don't count on counterions: The cyclic five-membered CSi(3)P cation 1 is synthesized in the reaction of benzamidinato-stabilized chlorosilylene and methyl phosphaalkyne. The presence of four π?electrons in 1 means it can be considered as a formal, heavier analogue of the cyclopentadienyl cation. Surprisingly the small counteranion (Cl(-)) does not contribute to the ring stability. 相似文献