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1.
Formation of 1-aryl-4-oxo-cyclohexa(e)nonecarboxylates from the Diels–Alder cycloaddition of 2-trimethylsilyloxy-1,3-butadiene and Danishefsky diene with aryl- and pyridylacrylates and further conversion thereof to spirocycles is described. This provides an efficient method for spiro oxindoles, azaoxindoles, and dihydroisoquinolones.
2.
This paper describes the development and validation of an analytical methodology to determine 28 polybrominated diphenyl ethers (PBDEs) in European eel (Anguilla anguilla) tissues using matrix solid-phase dispersion (MSPD) and gas chromatography coupled to triple quadrupole mass spectrometry (GC-QQQ-MS/MS). A total of 28 PBDEs were targeted, including tri- to deca-brominated congeners.The robustness and effectiveness of the proposed sample preparation procedure was demonstrated in lipid-rich eel tissues. The use of batch MSPD with activated silica gel and H2SO4-impregnated silica gel, followed by H2SO4 digestion and multilayer cartridge clean-up allowed for complete lipid removal and eliminated matrix effects during GC-QQQ-MS/MS analysis. The average PBDE recoveries from eel muscle samples spiked with PBDEs at two levels were in the range 56.2-119.0%. Precision was satisfactory since relative standard deviations were lower than 19.6%, regardless of spike level, and method quantification limits ranged between 1 and 170 pg g−1 (wet weight).The method demonstrated its successful application for the analysis of eel samples from two coastal lagoons located on the western French Mediterranean coast. All samples tested positive, but for tri- to hexa-brominated congeners only and total PBDE levels observed in this study were in the range 0.08-1.80 ng g−1 wet weight. 相似文献
3.
Development of an analytical procedure for determination of selected estrogens and progestagens in water samples 总被引:1,自引:0,他引:1
An analytical procedure has been developed for determination of eight selected natural and synthetic hormonal steroids in surface water and in effluent samples. Several methodological points have been investigated and are discussed; they include the choice of the solid-phase extraction sorbent, the influence of flow rate on recovery, the breakthrough volume for a given sorbent (Env+ and Oasis HLB), sample clean up, and sample storage. As regards the latter point, it was found that when no preservative was added to effluent from a sewage-treatment plant, severe loss of steroids occurred—85% of progesterone and about 30% of both estrone and estradiol were found to be degraded in 24 h. The procedure developed was applied to samples from the Seine river estuary. Sex steroids were not detected in surface water; estrone was the most commonly detected steroid in sewage-treatment plant effluent, with levels ranging from 1.8 to 8.3 ng L–1. Synthetic estrogens (ethynylestradiol and mestranol) and progestagens (levonorgestrel and norethindrone) were never detected, whatever the sampling season. Overall, for 162 out of 168 measurements levels were below the detection limits of the developed procedure. 相似文献
4.
Analysis of hormonal steroids in fish plasma and bile by coupling solid-phase extraction to GC/MS 总被引:1,自引:0,他引:1
Budzinski H Devier MH Labadie P Togola A 《Analytical and bioanalytical chemistry》2006,386(5):1429-1439
An analytical procedure for the simultaneous determination of twelve endogenous steroids (testosterone, androstenedione, 17β-estradiol,
estrone, pregnenolone, progesterone, dihydroandrostenedione, dihydrotestosterone, 11α-ketotestosterone, 17α-hydroxyprogesterone,
17α-hydroxypregnenolone, 17α,20β-dihydroxy-4-pregnen-3-one) in plasma and bile samples by solid-phase extraction (SPE) and
gas chromatography/mass spectrometry (GC–MS) has been developed. After enzymatic hydrolysis for bile samples only, samples
were concentrated and purified using two successive SPE (C18 and NH2) cartridges. Analytes were derivatized with a mixture of N-methyl-N-(trimethylsilyl)trifluoroacetamide (MSTFA) / mercaptoethanol / ammonium iodide (NH4I) and determined by GC–MS in selective ion monitoring mode. For most of the steroids monitored, recoveries were in the range
90–120% in plasma and in the range 60–70% in bile, and the reproducibility was below 10% for the complete procedure. Limits
of detection obtained ranged from 0.1 to 0.4 ng/g in fish plasma and from 1.6 to 14 ng/g in fish bile. The developed method
was successfully applied to the determination of plasma steroids in flounders (Platichthys flesus) collected from two French estuaries. 相似文献
5.
Nacima Memi Jasmina Muminovi Huremovi 《P-Adic Numbers, Ultrametric Analysis, and Applications》2020,12(1):49-59
We establish necessary and sufficient conditions for ergodicity of uniformly differentiable functions modulo p on ℤp. This result is applied to study ergodic rational functions on ℤ3. 相似文献
6.
We prove that certain means of the quadratical partial sums of the two‐dimensional Vilenkin‐Fourier series are uniformly bounded operators from the Hardy space to the space for We also prove that the sequence in the denominator cannot be improved. 相似文献
7.
Sebastián N. Jäger Exequiel O. J. Porta Guillermo R. Labadie 《Molecular diversity》2016,20(2):407-419
A diversity-oriented approach for the synthesis of various structurally different prenylated alcohols from readily accessible and common precursors was developed. With varying approaches, this article describes some successful examples of a Friedel–Crafts alkylation using methoxyphenols and different prenyl alcohols (geraniol and (E,E)-farnesol). We demonstrated that just by varying the stoichiometry of the Lewis acid used, the course of the reaction can be shifted to produce the alkylated or the cyclized product. Eighteen unique products were obtained with good isolated yields by direct alkylation with or without a consecutive \(\pi \)-cationic cyclization. 相似文献
8.
Bhattacharyya S Fan L Vo L Labadie J 《Combinatorial chemistry & high throughput screening》2000,3(2):117-124
Amine libraries and their derivatives are important targets for high throughput synthesis because of their versatility as medicinal agents and agrochemicals. As a part of our efforts towards automated chemical library synthesis, a titanium(IV) isopropoxide mediated solution phase reductive amination protocol was successfully translated to automation on the Trident(TM) library synthesizer of Argonaut Technologies. An array of 24 secondary amines was prepared in high yield and purity from 4 primary amines and 6 carbonyl compounds. These secondary amines were further utilized in a split synthesis to generate libraries of ureas, amides and sulfonamides in solution phase on the Trident(TM). The automated runs included 192 reactions to synthesize 96 ureas in duplicate and 96 reactions to synthesize 48 amides and 48 sulfonamides. A number of polymer-assisted solution phase protocols were employed for parallel work-up and purification of the products in each step. 相似文献
9.
10.
Sukanta Bhattacharyya Sunil RanaOwen W Gooding Jeff Labadie 《Tetrahedron letters》2003,44(27):4957-4960
A novel polymer-supported triacetoxyborohydride reagent for reductive amination of aldehydes and ketones is reported. The bound reagent was found to be shelf-stable and provided broad scope and reactivity in reductive amination reactions under mild reaction conditions. Streamlined protocols for its application in reductive amination reactions using both primary and secondary amines are described. 相似文献