摘要:

On-column enantiomerization is a well documented and practically important special case of the occurrence of a reversible reaction in a chromatographic reactor. The present paper explains the possibility to obtain enantiomerization rate constants from liquid chromatographic data using analytical equations derived for multi-step consecutive reactions. The results are compared with results from a finite difference method, and the application to experimental data is demonstrated.

ISSN:1082-6076    

DOI:10.1080/10826079808006610

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

A sensitive high-performance chromatographic method for the detection of amino acids and oligopeptides with pre-column fluorescence derivatization has been developed. Glycine, glycylglycine, triglycine, glutathion, glutamic acid, and cysteine were separated on a reversed-phase C18column with methanol-water-triethylamine as eluent; the derivatization and the chromatographic conditions were optimized. The six derivatives were eluted in 20 min with good reproducibility. The relative standard deviations (n=6) at an analytical concentration of 2 × 10−6M are less than 4.5%. The detection limits (signal-to-noise ratio=3) for the six derivatives are in the range of 15 46 fmol.

ISSN:1082-6076    

DOI:10.1080/10826079808006611

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

The chromatographic behavior of a group of polycyclic aromatic hydrocarbons in micellar liquid chromatography with a C1column and hexadecyltrimethylammonium bromide and n-propanol or n-butanol as hybrid mobile phases is studied. Four equations, proposed in the literature, correlating the retention parameter (e.g., Log k' or 1/k'), surfactant concentration, and alcohol percentage were checked.

ISSN:1082-6076    

DOI:10.1080/10826079808006612

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

A high performance liquid chromatrographic method has been developed for the analysis of dapsone and the five possible mono- and diglucosylamines formed by the reaction of dapsone with glucose. The identity of these glucosylamines has been elucidated by chemical interconversion, by spectroscopic means, and by assessment of their relative abundances at equilibrium. A novel method has been developed to enable the mono- and diglucosylamines to be quantitated using dapsone as an external standard.

ISSN:1082-6076    

DOI:10.1080/10826079808006613

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

The paper describes a new sensitive and selective thin layer chromatographic method for the detection of some organophosphorous pesticides. Fifteen organophosphorous pesticides have been separated on thin layer using different stationary phases prepared at the “Raluca Ripan” Institute of Chemistry Cluj-Napoca, Roumania (silica gel R, amino bonded silica gel R) and some mixtures with different polarities as mobile phase (petroleum ether + chloroform + ethyl acetate 65:30:5, v/v).

ISSN:1082-6076    

DOI:10.1080/10826079808006614

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

A HPLC method was developed to determine racemic thalidomide in plasma on a avidin protein column using solid phase extraction. The enantiomers were separated isocratically using a mobile phase of 2:98 v/v 2-propanol: phosphate buffer (0.1M, pH 4) at a flow rate of 0.6 mL/min at ambient temperature with detection at 300 nm. The chromatographic run time was less than 13 min. Calibration curves were prepared for each enantiomer in the range 100–5000ng/mL. The correlation coefficients for each enantiomer were greater than 0.999. The method is sensitive and can be used to measure plasma blood levels (100–1000ng/mL) of each enantiomer. The % RSD for quality control samples for both enantiomers were less than 10%. A C-18 SPE cartridge was used to extract the drug from plasma and recoveries of the enantiomers were greater than 95%. The limits of quantitation and detection were 100ng/mL and 50 ng/mL (s/n <3), respectively, for each enantiomer. Two of the commercially available metabolites of thalidomide were found not to interfere with the assay procedure.

ISSN:1082-6076    

DOI:10.1080/10826079808006615

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

An HPLC method was developed and subsequently validated for the quantitation of tobramycin and its related substances in an ophthalmic suspension. Current USP methodology for the assay of tobramycin involves pre-column derivatization with 2,4-dinitrofluorobenzene. The USP assay method was modified to encompass the determination of two known impurities (neamine and kanamycin) and a degradation product (nebramine). The method development involved evaluation of several factors including derivatization parameters (time, temperature, and acid concentration), mobile phase composition, column choice and temperature, wavelength evaluation, and response factors.

ISSN:1082-6076    

DOI:10.1080/10826079808006616

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Deslorelin is a nonapeptide drug used for precocious puberty in young women. A reversed phase HPLC procedure was developed for the analysis of deslorelin and benzyl alcohol in a parenteral solution dosage form. Both the nonapeptide drug (deslorelin) and the preservative (benzyl alcohol) were determined from a single injection. The separation and quantitation were achieved on a C18column at ambient temperature using a mobile phase of 70:30 v/v aqueous phase:acetonitrile containing sodium hexylsulfonate and triethylamine at pH 3. The wavelengths for spectrophotometric detection were 275 nm for deslorelin and 254 nm for benzyl alcohol. The method showed linearity, precision and accuracy for deslorelin (2.93–550 mg/mL) and benzyl alcohol (0.059–11 mL/mL) over a large concentation range (0.6%–110% of the label concentration). The lower limits of quantitation for deslorelin and benzyl alcohol were 2.93 g/mL and 0.059 l/mL respectively.

ISSN:1082-6076    

DOI:10.1080/10826079808006617

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Solid phase extraction technique has been evaluated for the treatment of urine samples in the analysis of cephalosporins before injection into an HP-Hypersil ODS-C18column. Cephalexin, cefotaxime, cefazolin, cefuroxime, and cefoxitin were tested with seven different reversed-phase extraction column cartridges and the obtained urine extracts were not clean. However, 3M Empore extraction disk cartridges packed with octadecyl (C18) bonded silica provided clean extracts with a single extraction. The recoveriés of the five cephalosporins ranged from 56 to 60 % in the 1.25–500 g/mL concentration range. The assay was accurate, precise, and adequate for testing the drug content in urine samples. The detection limit found for the five drugs was 0.25 g/mL after an injection of 10 L. The reliability of this study was tested by analyzing a urine sample containing cefuroxime after a minimum single dose administration (250 mg).

ISSN:1082-6076    

DOI:10.1080/10826079808006618

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Solid phase extraction (SPE) is an efficient pretreatment method to separate a compound of interest in complicated matrix such as body fluid, food, or in soil. Ultrafiltration is also a suitable pretreatment method to remove higher molecular weight compounds such as protein in body fluid. The latter method is also useful for differential analysis of free type from protein-bound type compound in body fluid. Free type compound after ultrafiltration will exist in filtrate. Previously ultrafiltration and SPE were carried out off-line and the former was done manually, which was troublesome for routine analysis. In this paper these pretreatment methods were successfully on-line combined and controlled by computer first by the author. Unfortunately this kind of equipment is not currently available in the market yet due to patent restriction.

ISSN:1082-6076    

DOI:10.1080/10826079808006619

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor