A sensitive and selective high performance liquid chromatography-peroxyoxalate chemiluminescence (PO-CL) method has been developed
for the simultaneous determination of chlorpheniramine (CPA) and monodesmethyl chlorpheniramine (MDCPA) in human serum. The
method combines fluorescent labeling with 4-(4,5-diphenyl-1H-imidazole-2-yl)phenyl boronic acid using Suzuki coupling reaction with PO-CL detection. CPA and MDCPA were extracted from
human serum by liquid–liquid extraction with n-hexane. Excess labeling reagent, which interfered with trace level determination of analytes, was removed by solid-phase
extraction using a C18 cartridge. Separation of derivatives of both analytes was achieved isocratically on a silica column
with a mixture of acetonitrile and 60 mM imidazole-HNO3 buffer (pH 7.2; 85:15, v/v) containing 0.015% triethylamine. The proposed method exhibited a good linearity with a correlation coefficient of 0.999
for CPA and MDCPA within the concentration range of 0.5–100 ng/mL. The limits of detection (S/N = 3) were 0.14 and 0.16 ng/mL
for CPA and MDCPA, respectively. Using the proposed method, CPA could be selectively determined in human serum after oral
administration. 相似文献
Efficient couplings using equimolar quantities of each coupling partner and multiple C? H bond arylation reactions are achieved with an Ir‐based catalytic system for the C? H bond arylation of electron‐rich heteroarenes with iodoarenes to construct extended π‐systems. The dramatic ligand effect on reaction efficiency leads to the discovery that Crabtree's catalyst (see scheme) is the optimal catalyst precursor.
It is shown for a model system consisting of spherical particles confined in cylindrical pores that the first ten close-packed phases are in one-to-one correspondence with the first ten ways of folding a triangular lattice, each being characterized by a roll-up vector like the single-walled carbon nanotube. Phase diagrams in pressure-diameter and temperature-diameter planes are obtained by inherent-structure calculation and molecular dynamics simulation. The phase boundaries dividing two adjacent phases are infinitely sharp in the low-temperature limit but are blurred as temperature is increased. Existence of such phase boundaries explains rich, diameter-sensitive phase behavior unique for cylindrically confined systems. 相似文献
[Structure: see text] The AuCl-catalyzed benzannulation of o-alkynyl(oxo)benzenes with benzenediazonium 2-carboxylate proceeds under mild conditions and a variety of anthracene derivatives, having a ketone group at the 9-position, are produced in good to high yields. The reaction proceeds most probably through the [4+2] cycloaddition between benzyne and benzopyrylium auric ate complex, which would be generated by the gold-induced electrophilic cyclization of o-alkynyl(oxo)benzenes. 相似文献
We developed a fluorous scavenging–derivatization method for reagent peak-free liquid chromatography (LC)–fluorescence analysis
of carboxylic acids. In this method, carboxylic acids were fluorescently derivatized with 1-pyrenemethylamine in the presence
of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide and 1-hydroxy-1H-benzotriazole. Residual excess unreacted reagent was tagged with 2-(perfluorooctyl)ethyl isocyanate and could be selectively
removed by microfluorous solid-phase extraction before LC analysis. With use of this method, eight fluorescent derivatives
of linear aliphatic carboxylic acids (C1–C8) can be separated within 30 min by reversed-phase LC with gradient elution. In the chromatogram obtained, the fluorous-tagged
unreacted reagent peak is greatly decreased after microfluorous solid-phase extraction and does not interfere with the quantification
of each acid. With use of microfluorous solid-phase extraction with 80% (v/v) aqueous methanol elution, over 99.9% of the
unreacted fluorescent reagent was removed. The detection limits (signal-to-noise ratio of 3) for the carboxylic acids examined
are 2.3–8.0 fmol per 10-μL injection. We also applied this method successfully to the analysis of highly polar carboxylic
acids such as α-keto acids and tricarboxylic acid cycle metabolites. 相似文献
Synthesis of beauveriolide III (1b), which is an inhibitor of lipid droplet accumulation in macrophages, was achieved by solid-phase assembly of linear depsipeptide using a 2-chlorotrityl linker followed by solution-phase cyclization. On the basis of this strategy, a combinatorial library of beauveriolide analogues was carried out by radio frequency-encoded combinatorial chemistry. After automated purification using preparative reversed-phase HPLC, the library was tested for inhibitory activity of CE synthesis in macrophages to determine structure-activity relationships of beauveriolides. Among them, we found that diphenyl derivative 7{9,1} is 10 times more potent than 1b. 相似文献
The synthesis and functional analysis of KL001 derivatives, which are modulators of the mammalian circadian clock, are described. By using cutting‐edge C H activation chemistry, a focused library of KL001 derivatives was rapidly constructed, which enabled the identification of the critical sites on KL001 derivatives that induce a rhythm‐changing activity along with the components that trigger opposite modes of action. The first period‐shortening molecules that target the cryptochrome (CRY) were thus discovered. Detailed studies on the effects of these compounds on CRY stability implicate the existence of an as yet undiscovered regulatory mechanism. 相似文献
A liquid chromatographic (LC) determination of catecholamines and indoleamines is described. This is based on intramolecular excimer-forming fluorescence derivatization with 4-(1-pyrene)butanoyl chloride, followed by reversed-phase LC. The analytes, containing an amino moiety and phenolic hydroxyl moieties in a molecule, were converted to the corresponding polypyrene-labeled derivatives by one-step derivatization. They afforded intramolecular excimer fluorescence, which can clearly be discriminated from the normal fluorescence emitted from reagent blanks. The detection limits (S/N = 3) for catecholamines and indoleamines were femto-mole levels per 20-microL injection. Furthermore, this method was applied to a urine assay. 相似文献
[reaction: see text] The iron-catalyzed cross-coupling reaction of alkenyl sulfides with Grignard reagents is described. While the cross-coupling proceeds efficiently at alkenyl-S bonds, almost no cross-coupling takes place at aryl-S bonds, attesting to a unique selectivity of iron catalysis. The beneficial effect of potentially coordinating 2-pyrimidyl group on sulfur is also described. 相似文献