摘要:

Three–dimensional surfaces, based on a large set of experi-mental data, have been built to investigate and describe the interrelations between different physico–chemical properties of two-phase liquid systems, the operating conditions of the planetary centrifuge, and the stationary phase retention. The wide range of alteration of interfacial tension, density, and viscosity differences between two phases has been provided by changing the composition of liquid systems containing an organic solvent, an extracting reagent, water and a mineral salt, the organic solvents, and extracting reagents of different nature being considered. A great body of data presents a possibility of estimating the contributions from all the enumerated physico-chemical properties of liquid systems to the stationary phase retention.

ISSN:1082-6076    

DOI:10.1081/JLC-100101479

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

When the Cu(II), Co(III), Ni(II), and Fe(II) chelates with 2-(5-Nitro - 2-pyridyl - 5 - [N-propyl-N-sulphopropyl)amino]phenol (Nitro-PAPS) were separated on octadecylsilane (ODS) stationary phase (Kaseisorb ODS Super and Kaseisorb LC ODS-300-5) by the addition of several quaternary ammonium salts (Q+Br-) individually to the aqueous ACN mobile phase, a correlation of these hydrophobic cation's character with the retention of the chelates was examined. The degree of the variation of the stationary phase due to the adsorption of quaternary ammonium ion (Q+) is measured by using a series of elution time of a solute, which was obtained by its successive injection. When the alkyl group of Q+is larger, the period for attaining the equilibrium becomes longer. As a concentration of Q+is higher, the period becomes longer.

ISSN:1082-6076    

DOI:10.1081/JLC-100101480

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

A rapid, accurate, and sensitive method has been developed for the quantitative determination of iodoamino acids, namely thyroxine (3,5,3′,5′-tetra-iodothyronine, (T4) and 3,5,3′-tri-iodothyronine (T3). These compounds are essential indicators in the clinical diagnosis of thyroid gland diseases.

ISSN:1082-6076    

DOI:10.1081/JLC-100101481

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

A simple reversed phase HPLC method was developed for the determination of polyamines (putrescine, cadaverine, spermidine, spermine) and other polycations (n-acetyl putrescine, histamine, n-acetilspermine, agmatine), as their benzoylated derivatives. The advantages of this method,examined in various matrixes (hypothalamus, hypophyses, ovary, and seminal plasma), are its versatility, simplicity, and short time of determination of polyamines and related substances of importance in prokaryotes and eukaryotes, even in different matrixes, using a standard HPLC equipment (UV detection at 254 nm), with good resolution, sensitivity, and reproducibility.

ISSN:1082-6076    

DOI:10.1081/JLC-100101482

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Rapid, accurate and reliable high performance liquid chromatographic methods for the determination of non-steroidal anti-inflammatory drugs epirizole and tiaramide in pharmaceutical preparations were developed using triethylamine, a modifying agent to the mobile phase. Extraction was carried out with methanol-water (1:1,v/v) after grounding tablet and granule preparations. The methods utilized reversed phase C18 column, UV monitoring at 250 nm, ethylp-hydroxybenzoate as an internal standard for epirizole, and at 295 nm, methylp-aminobenzoate as an internal standard for tiaramide. Regression analyses of three standard plots in concentration ranges of 0.05–0.4 mg/mL for epirizole and 0.18–1.44 mg/mL for tiaramide gave respective correlation coefficients >0.99998 and >0.99997. Relative standard deviations of the slopes were 0.180% and 0.888%, respectively. Percentage recoveries of these compounds for four commercially available drugs ranged between 99.06 and 103.14 and between 99.15 and 99.71 of the labeled amounts of epirizole and tiaramide, respectively. The methods were successfully applied to determine contents of epirizole and tiaramide in marketed drugs.

ISSN:1082-6076    

DOI:10.1081/JLC-100101483

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

A simple, rapid, sensitive, reproducible, and accurate HPLCprocedure employing a narrow bore reversed phase column and a diode-arraydetector is proposed for the determination of ϵ-N-2-furoylmethyl-L-lysine(furosine) in acid hydrolyzed of milk and powdered milk samples.

ISSN:1082-6076    

DOI:10.1081/JLC-100101484

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Using the results of high performance liquid chromatography (HPLC), this paper investigates the separation and inclusion of a series of weakly polar imidazole derivatives, with hydroxypropylβ -cyclodextrin (HP-β-CD) in the mobile phase over a wide range of column temperatures.These compounds are used for the treatment of onychomycosis. Gibbs Helmholtz parameters (Δ(ΔH) and Δ(ΔS)) of two adjacent imidazole peak on a chromatogram were determined from the graph of the logarithm of the separation factor,α, against the reciprocal of the temperature. A temperature dependent reversal of the elution order between a pair of imidazole derivatives was studied.

ISSN:1082-6076    

DOI:10.1081/JLC-100101485

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

The retention and separation of ten iridoid glucosides typical for the plants of genusGalium(Rubiaceae) were examined by RP-HPLC on octadecyl (ODS) column with water-methanol mobile phases. The compounds have the same basic carbon skeleton with a glucose moiety at C-1 but differ by the type, the number, and the position of the additional functional groups. In general, the retention increased with the increasing total hydrophobicity of the molecule, but was substantially affected by the different combinations of free and esterified hydroxyl and /or carboxyl groups. The water-based mobile phase, the high polarity and the bulky structure of the iridoid glucosides examined suggested that the solute-mobile phase interactions dominated in the retention mechanism. Water-methanol (85:15, v/v) was found to be a suitable mobile phase for the fractionation of the iridoid glucosides into acidic and non - acidic components on a single column.

ISSN:1082-6076    

DOI:10.1081/JLC-100101486

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Capillary liquid chromatography combined with solid phase extraction in a column packed with an anion exchanger based on MFE-Polymer (hydroxyethylmethacrylate, HEMA) containing quaternary ammonium functional groups, has been studied for multiresidual analysis of seven chlorophenoxy acid herbicides; 2,4-D, MCPA, 2,4-DP, 2,4-DB, MCPB, 2,4,5-TP, and the benzoic acid derivative Dicamba in green bean samples. The chromatographic analysis was carried out on a C18packed capillary column with gradient elution at 20°C. The chlorophenoxy acid and Dicamba have been assayed in green bean samples spiked with amounts between 0.30 and 0.08 mg.kg−1for 2,4-D and MCPA, and between 0.15 and 0.04 mg.kg−1for all the other herbicides. The recoveries obtained were between 41 and 119% (n=4 for each spiked level).

ISSN:1082-6076    

DOI:10.1081/JLC-100101487

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

High performance liquid chromatography procedures using non-porous ODS columns were developed for the assay of aspirin-caffeine-butalbital (mixture 1) and acetaminophen-caffeine-butalbital (mixture 2). The separation and quantitation of Mixture 1 were achieved on a 3.0 μm non-porous silica ODS column at ambient temperature using a mobile phase of 98:2 v/v 50 mM phosphate buffer pH 3.0-acetonitrile at a flow rate of 1.5 mL/min with detection at 220 nm. The method showed linearity for aspirin-caffeine-butalbital in the 325–6500, 40–800, and 50–1000 ng/mL ranges, respectively. Intra- and inter-day RSD values were 0.19–1.72% and 1.30–1.49% for aspirin, 0.08–1.17% and 0.06–1.09% for caffeine, and 0.09–1.55% and 0.07–2.10% for butalbital, respectively. Accuracy of intra and inter-day were in the 0.70–1.27% and 0.20–1.13% for aspirin, 0.05–0.06% and 0.004–0.09% for caffeine, and 0.02–0.09 and 0.02–0.05% for butalbital, respectively.

ISSN:1082-6076    

DOI:10.1081/JLC-100101488

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor