摘要:

Size exclusion chromatography of several polystyrene (PS) standards of a narrow molecular weight (MW) distribution was performed with an on-line light scattering detector (MALLS) using Shodex SEC column KF 806L packed with PS gel packings. Tetrahydrofuran was used as the mobile phase and the flow rate was 1.0 mL/min. Mechanical degradation of the sample PS was not observed even the PS sample having MW four million daltons. MW averages obtained after elution were comparable to those of vendor's values. Peak width of RI (refractometer) chromatograms increased with increasing sample concentrations and polymer components composed of the chromatograms had approximately the same MW except both ends of the chromatograms. This observation is attributed to the overloading effect and the preferable sample concentration should be as low as possible. The breakthrough volume was independent on the sample concentration, although the peak retention volume increased with the sample concentration. The decrease in molecular size with increasing sample concentration was not observed and therefore, the increase in the peak retention volume with increasing sample concentration is considered to be attributed to the overloading effect, not to the decrease in the hydrodynamic volume.

ISSN:1082-6076    

DOI:10.1080/10826079608001219

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

A simple high performance liquid chromatographic (HPLC) procedure for the simultaneous determination of fentanyl and its wo major metabolites in biological samples was used in blood samples from 6 preterm sick newborn infants. A 8 mm x 100 mm, 4 μm cyano column, 0.05 m phosphate buffer adjusted at pH 3.2 and acetonitrile (50:50 V/V) as mobile phase, were used at a flow rate 2.5 ml/min. Each run was completed within 10 minutes. The detection limits for the analysis were 0.10 ng, 0.15 ng and 0.10 ng for norfentanyl, fentanyl and despropiofentanyl, respectively, with 50 μl injection for all the compounds at a signal-to-noise ratio of 3. The respective retention times were 4.62±0.10, 6.20±0.76 and 6.71±0.73 minutes for norfentanyl, fentanyl and despropiofentanyl. Microassay is simple, rapid and precise. This assay may be used for the therapeutic drug monitoring in newborn babies.

ISSN:1082-6076    

DOI:10.1080/10826079608001220

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Twenty-two sulphonamides and the three commonly used dihydrofolate reductase inhibitors have been subjected to an investigation of retention behaviour on a silica based reversed phase. Effects of variation in the percentage of methanol and the pH have been determined isocratically and the methanol gradients developed have been modified by variations in the concentration of the phosphate buffer. Significant variations in retention behaviour were observed such that the majority of combinations of drugs could be screened for. No set of conditions studied gave rise to a total separation of all drugs, but around twenty drugs were commonly resolved.

ISSN:1082-6076    

DOI:10.1080/10826079608001221

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Nadolol (SQ 11725) is a β-adrenergic blocker which has two chiral centers, this allows for the presence of two racemates known as racemate A (SQ 12181) and racemate B (12182) and a total of four enantiomers. A simple isocratic HPLC method is developed for the separation of nadolol racemate A (SQ 12181) to its corresponding enantiomers RSR-nadolol (SQ 12148) and SRS-nadolol (SQ 12150) and racemate B (SQ 12182) to its corresponding enantiomers RRS-nadolol (SQ 12149) and SSR-nadolol (SQ 12151). Hexane with different percentage of ethanol containing 0.4% diethylamine is used as a mobile phase.

ISSN:1082-6076    

DOI:10.1080/10826079608001222

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Methyl anthranilate fortified blueberries were extracted with methanol, cleaned up by solid phase extraction and analyzed by reverse phase high performance liquid chromatography. Methyl anthranilate was quantified by UV absorbance and fluorescence detection. Recoveries of 70 ± 13% and 14% were obtained for blueberry samples fortified with methyl anthranilate at 5 and 0.15 ppm respectively. The method limits of detection for ultraviolet and fluorescence detection were 0.04 and 0.009 μg methyl anthranilate/g, respectively.

ISSN:1082-6076    

DOI:10.1080/10826079608001223

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

A liquid chromatographic method incorporating column-switching for the separation and determination of chlorthalidone enantiomers in urine is described. Untreated urine samples (50 μL) were directly introduced into a 20 mm x 2.1 mm I. D. precolumn packed with a Hypersil ODS-C18, 30 μm, stationary phase. Polar urinary compounds were removed by flushing the precolumn with 4 mL of water (pumped at a flow rate of 1 mL/min), and the racemic analyte was then transferred to a LiChroCART ChiraDex, 5 μm, 250 mm x 4 mm I. D. column, where the enantiomers were separated by means of a methanol/0.05 M acetate buffer adjusted to pH 4 mobile-phase (40:60, v/v), and quantified at 230 nm. The system shows good linearity and reproducibility in the 0.25 - 5.0 μg/mL, thus covering therapeutic levels of chlorthalidone in urine. The usefulness of the described procedure has been tested by analyzing urine samples obtained after drug administration.

ISSN:1082-6076    

DOI:10.1080/10826079608001224

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

The new prototype of the cross-axis coil planet centrifuge (X-axis CPC) fabricated in our laboratory provides various improvements over the original unit such as ambient temperature control, good visibility of the rotary frame and substantial reduction of the torque by a round transparent case, direct motor shaft coupling to the rotary frame to stabilize the system, and ease of belt tension adjustment using idler pulleys. The capability of the system was demonstrated in the separation of stable proteins with a polymer phase system using a pair of eccentric coil assembly separation columns. Cytochrome C, myoglobin and trypsinogen were well resolved and eluted in 5.5 h at a partition efficiency of 200 theoretical plates. The method provides a gentle environment for proteins without causing their deactivation or loss.

ISSN:1082-6076    

DOI:10.1080/10826079608001225

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Although the renewable, needle bio-mass ofTaxusxmediaHicksii was proposed as the future source for paclitaxel in 1990, no details for the actual isolation of paclitaxel and other taxanes have been published, other than testing the extracts by HPLC analysis. Compared to the bark, the needle source poses additional problems, eg. chlorophylls, waxes and co-eluting taxanes, and thus, there is a need for an efficient method.

ISSN:1082-6076    

DOI:10.1080/10826079608001226

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

A thorough analysis of a new commercially available pepsin chiral stationary phase (CSP) has been completed using seproxetine (S-norfluoxetine) hydrochloride bulk drug substance and R-norfluoxetine hydrochloride as the test analytes. Chromatographic properties of this new Ultron ES-Pepsin column were investigated by varying key mobile phase parameters (pH, flow rate, buffer strength and organic concentration), column temperature and sample loading. After observing and plotting changes in retention, resolution and theoretical plates based on corresponding variation in these parameters, it is possible to choose conditions for the separation that are optimum and robust. The subsequent method validation demonstrated acceptable precision, linearity, recovery, selectivity, limit of detection and ruggedness for the determination of R-norfluoxetine in seproxetine hydrochloride bulk drug substance.

ISSN:1082-6076    

DOI:10.1080/10826079608001227

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

We describe an HPLC procedure for the separation of dansyl (Dns)-derivatives of all common amino acids present in polypeptide hydrolyzates. A linear gradient of solvent B [methanol: water, 70:30, (v/v)] in solvent A [30 mM sodium phosphate buffer, pH 7.4, containing 5 mL methanol and 6.5 mL tetrahydrofuran (THF)], from 0 to 100% B in 30 min, at 1.0 mL/min and 25°C, was used to elute the Dns-amino acids from a 4 μm NovaPak C18column with good resolution. The Dns-amino acids were detected fluorometrically at 338 nm wavelength excitation and 455 nm emission.

ISSN:1082-6076    

DOI:10.1080/10826079608001228

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor