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At least 109 records · Page 6Linked to original sources
PubMed1995

Micellar liquid chromatographic separation of sulfonamides in physiological samples using direct on-column injection.

A mixture of twelve sulfonamides was separated by micellar liquid chromatography (MLC) using sodium dodecyl sulfate (SDS) micelles and a hydrophilic endcapped C18 column. Retention behavior and selectivity pattern of sulfonamides in MLC were examined with the change of SDS concentration and volume fraction of an organic modifier (1-propanol). The suitable condition was found to be 0.070 M SDS and 6.0% 1-propanol for the separation of these twelve sulfonamides. Under this condition, the isocratic separation of the sulfonamides was achieved within 15 min with a relatively high column efficiency for MLC (ca. 7000 plates/25 cm column). Retention times of these twelve sulfonamides were found to be very repeatable, which is due to the highly reproducible retention behavior in MLC. The same twelve sulfonamides were successfully separated in the spiked physiological fluids (human urine and cow milk) through direct on-column injection by MLC.

Animals↗
PubMed1997

High performance liquid chromatographic analysis of selected sulfonamides in plasma.

Chromatographic conditions were elaborated to evaluate a model mixture of four sulfonamides (sulfamethoxazole, sulfamoxole, sulfisoxazole and sulfamethoxydiazine) in plasma using a reversed phase HPLC C18 column and a mobile phase composed of methanol and phosphate buffer (60:40; v/v) at pH 5.0. The detection was made using an electrochemical detection with the potential set at 1.1 V. In the case of sulfonamides deproteination of plasma with methanol was more advantageous than extraction with organic solvents. The recovery of analysed sulfonamides was in the range of 95-97%, the detection limits were 10 ng/ml of plasma.

Chromatography, High Pressure Liquid↗
PubMed2006

Asymmetric radical addition of ethers to enantiopure N-p-toluenesulfinyl aldimines, mediated by dimethylzinc-air.

Asymmetric radical addition of ethers to enantiopure aromatic N-p-toluenesulfinyl aldimines has been achieved. The requisite radicals were generated by dimethylzinc-air. Lewis acid activation of the N-p-toluenesulfinyl aldimines followed by radical addition gives a mixture of sulfinamide and sulfonamide products. Subsequent treatment of the mixture with dry m-CPBA affords the sulfonamide product in enantiomerically enriched form. [reaction: see text]

Air↗
PubMed1977

Direct spectrophotometric determination of sulfathiazole in presence of sulfadiazine and sulfamerazine.

A direct spectrophotometric method for the quantitative determination of sulfathiazole and the total pyrimidyl sulfonamide content in a mixture containing sulfadiazine and sulfamerazine is reported. This three-component system was readily reduced to the problem of a simple two-component system analysis. Based on dual isoabsorptive wavelength spectroscopy, simultaneous equations were developed that required absorbance measurements at only two selected wavelengths both isoabsorptive. The location of the isoabsorptive wavelengths was dependent on the pH of the solvent medium, and 0.1 M HCl gave the best results. The validity of the derived equations was demonstrated in a recovery study involving synthetic mixtures containing varying quantities of the three sulfonamides. The recovery was linear over a wide concentration range, and the precision of the method was about 1%.

Methods↗
PubMed1999

HPLC/atmospheric pressure chemical ionization-mass spectroscopy of eight regulated sulfonamides.

Reversed phase high performance liquid chromatography coupled with on-line atmospheric pressure chemical ionization mass spectrometry, HPLC,APCI-MS, has been applied to a mixture of eight sulfonamides. In full scan mode, extracted ion chromatograms produced minimum detectable quantities (MDQ) of 0.8 ng on column, for six of the eight regulated sulfonamides investigated. Selected ion monitoring yielded a 50 pg MDQ for sulfamerazine, sulfadiazine and sulfamethazine, while, the other compounds presented higher values. Analysis of supercritical fluid extracts of chicken liver containing sulfadimethoxine were found to be easily detected by HPLC/APCI-MS. In extracts of chicken liver spiked with 25 microg/kg(-1) (25 ppb) of sulfadimethoxine this compound could be detected in selected ion mode, while 100 pg/microl(-1) was detectable in either full scan or single ion modes. The analysis method for extracted sulfadimethoxine also demonstrated good linearity and reproducibility in both single ion and scan mode.

Animals↗
PubMed2002

Oxidative degradation of a sulfonamide-containing 5,6-dihydro-4-hydroxy-2-pyrone in aqueous/organic cosolvent mixtures.

PURPOSE: To predict the oxidative stability of a sulfonamide-containing 5,6-dihydro-4-hydroxy-2-pyrone in lipid-based delivery systems, N-(3-(1[(3alpha,6R)-4-hydroxy-2-oxo-6-phenyl-6-propyltetrahydro-2H-pyran-3-yl]propyl)phenyl)-5-(trifluoromethyl)-2-pyridinylsulfonamide (DHP) was oxidized by peroxides and peroxyl radicals in binary mixtures of water and organic cosolvents. METHODS: DHP was oxidized by hydrogen peroxide, t-butylhydroperoxide, or peroxyl radicals derived from the thermal decomposition of 2,2'-azobis(2-amidinopropane) dihydrochloride (AAPH) in 40% (v/v) organic cosolvent and 5 mM buffer at or near 40 degrees C. Interactions between DHP and ]propane sulfonic acid and imidazole) and DH- were assessed by 1H-NMR spectroscopy. The formation of CO likely involves a free radical mechanism. RESULTS: The reaction of DHP with peroxides in 40% (v/v) acetonitrile yields epimeric monohydroxylation products, R-OH and S-OH, at C-3 of the pyrone ring, and a keto-derivative (CO). Hydroxylation rates depend on the protonation state of DHP, and the nature of buffer and the organic cosolvent. Organonitriles accelerate the oxidation through formation of peroxycarboximidic acid. Peroxyl radicals do not yield significant amounts of R/S-OH or CO. CONCLUSIONS. The hydrogen peroxide-induced degradation of DHP in the presence of acetonitrile involves two reactions, hydroxylation and carbonyl formatin. Hydroxylation proceeds via nucleophilic attack by the monodeprotonated form of DHP (DH-) on peroxycarboximidic acid. The oxidation rate is slowed by ion pairing between nitrogen-containing buffers ([3-N-morpholino]propane sulfonic acid and imidazole) and DH-. The formation of CO likely involves a free radical mechanism.

Organic Chemicals↗
PubMed1999

Fast liquid chromatographic-mass spectrometric determination of pharmaceutical compounds.

We present fast LC-MS-MS analyses of multicomponent mixtures containing flavones, sulfonamides, benzodiazepines and tricyclic amines. Using a short microbore HPLC column with small particle size, five to eight compounds were partially resolved within 15 to 30 s. TurboIonSpray and atmospheric pressure chemical ionization interfaces were well suited to tolerate the higher eluent flow-rates of 1.2 to 2 ml/min. The methods were applied to biological sample matrices after clean-up using solid-phase or liquid-liquid extraction. Good precision and accuracy (average 8.9 and 97.7%, respectively) were achieved for the determination of tricyclic amines in human plasma. Benzodiazepines were determined in human urine with average precision of 9% and average accuracy of 95% for intra- and inter-assay. Detection limits in the low ng/ml range were obtained. An example for 240 injections per hour of demonstrated the feasibility of rapid LC-MS-MS analysis.

Amines↗