摘要:

The chiral selectivities of N-(tert.-butylaminocarbonyl)-(S)-valylaminopropylsilica gel and (R)-1-(α-naphthyl)-ethyl-aminocarbonyl-glycylaminopropylsilica gel were studied using model compounds. The differences in the final energy values of molecular interactions between the model chiral phase and derivatized (R)-and (S)-amino acids, calculated by molecular.

ISSN:1082-6076    

DOI:10.1080/10826079608006312

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Modelling of the retention of solutes in micellar liquid chromatography allows the optimization of the resolution of a mixture of solutes and the determination of physico-chemical retention parameters. Both tasks imply the calculation of capacity factors, which are severely affected by the value of dead time. However, the determination of the dead time is not easy when a micellar mobile phase is used owing to the wide and variable perturbations that appear at the heads of the chromatograms. Four different criteria of determination of a reference time in the chromatograms are proposed and compared. The criteria are applied to mobile phases containing a varying concentration of surfactant and modifier, in order to observe the dependence of the reference time with the mobile phase composition. The study of the influence of the errors in the dead time on the modelling of the retention indicated that an accurate dead time is necessary to calculate retention parameters, but an excellent prediction of retention times can be achieved with a wide range of values of dead time.

ISSN:1082-6076    

DOI:10.1080/10826079608006313

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Methods for the determination of the anionic surfactant Dowfax 8390 are described. Dowfax is a complex mixture of various alkylated and sulfonated diphenyl oxides. The primary component of Dowfax is monoalkylated disulfonated diphenyl oxide (MADS). This work uses ion pairing chromatography and reverse phase chromatography. Ion pairing chromatography provides a simple and fast method for quantitation of the total concentration of Dowfax surfactant in aqueous solutions. It is shown that suppressed conductivity detection and optical detection at 210 nm have comparable sensitivity. A quantitation limit of 48.4 ppm is achieved with 400 μl injection. The separation of 11 components in Dowfax is achieved using gradient reverse phase chromatography.

ISSN:1082-6076    

DOI:10.1080/10826079608006314

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

This paper reports the results of a study performed to develop a rapid and straightforward chromatographic method for the identification and dosage of 5-hydroxymethyl-2-furaldehyde (HMF) and 2-furaldehyde (FA), which are recognized indices of deteriorative changes in commercially processed food. The method employs a Supelco microbore reversed phase column (300 × 1.0 mm I.D.), eluted isocratically with a 94:6 (v/v) water/acetonitrile mixture at flow rate of 60 μL/min. Sample is detected at 280 nm in a micro flow cell of 300 nl. Peak purity and identification is assessed by comparing the UV spectra monitored at two points through the chromatographic peak in continuous flow mode in the range from 200 to 400 nm. This method is successfully applied to the identification and quantitative determination of HMF and FA in alcoholic and non-alcoholic beverages by an internal standard method without any sample pretreatment.

ISSN:1082-6076    

DOI:10.1080/10826079608006315

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

This paper describes the direct injection analysis of the anti-cancer drug mitomycin C in biological fluid by an HPLC column switching technique. The first chromatographic column which provides for sample extraction and clean up employs a micellar mobile phase with SDS as the modifier. The second column, coupled on-line to the first, utilizes reverse-phase conditions for analysis. UV detection is employed at 365nm. Samples from cancer patients and dogs were analyzed. The drug recoveries are 95.9–100.3% with a relative standard deviation of 2.76%. A sample analysis is completed within 15 minutes.

ISSN:1082-6076    

DOI:10.1080/10826079608006316

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Dextromethorphan is a non-narcotic antitussive drug that recently attracted interest because of its anticonvulsant and neuroprotective properties. Dextromethorphan undergoes polymorphic oxidation and 5–10% of human subjects are characterised as poor metabolizers on the basis of the formation rate of its O-demethylated metabolite, dextrorphan catalysed by isozyme CYP2D6.

ISSN:1082-6076    

DOI:10.1080/10826079608006317

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

A sensitive, reproducible and rapid HPLC assay was developed for preformulation and stability studies of a potential radioprotector, S-2-(3-methylaminopropylamino) ethyl-phosphorothioate, WR-3689. This method is based on the elution of WR3689 by high performance ion-pair reverse phase liquid chromatography using an electrochemical detector with an oxidation potential set at + 0.19 v. The detector response was found to be linear over the concentration range of 0.02–20 μg/mL with an absolute limit of quantitation of 170 pg. The coefficient of variation ranged from 0.75–6.52% for the interday reproducibility. This HPLC assay was employed to determine the stability of WR-3689 at various pH (2, 4, 7, 10 and 12) and temperatures (22 °C, 35 °C, 43 °C and 100 °C). Results of the stability studies indicated that WR-3689 is more stable in basic than in acidic aqueous solutions. For example, the half-life of WR-3689 at 45 °C was 13.8 days at pH 12 as compared to 12.7 h at pH 4. With regard to the effect of temperature, the half-life of this compound increased from 19.2 h at 43 °C to 41.8 days at 22 °C. In conclusion, the excellent reproducibility and stability indicating capacity of this assay makes it a useful method for formulation studies. The high sensitivity and specificity of this assay make it useful for pharmacokinetic studies.

ISSN:1082-6076    

DOI:10.1080/10826079608006318

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Three databases of HPLC retention indices in the 1-nitroalkane scale were recently established (IFM = Institute of Forensic Medicine, MCL = Microchemistry Laboratory, MTSS = Merck Tox Screening System). In two of them (IFM and MTSS) virtually identical chromatographic conditions were applied but different RP-columns. In the third system (MCL) a different column and different elution conditions were used. Among a total of 1149 drugs examined in all three labs, 258 drugs were common for IFM and MTSS, 179 were common for MCL and MTSS, 162 were common for IFM and MCL, and 135 drugs were common for all three databases.

ISSN:1082-6076    

DOI:10.1080/10826079608006319

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

The application of a column switching HPLC system to the analysis of the antimalarial proguanil and its two metabolites in plasma and saliva is described. The assay is based on a previously developed hydrophobic ion-pairing separation using sodium dodecylsulphate on ODS Hypersil. The use of a precolumn to concentrate and allow pre-treatment of these drugs in the two matrices is shown. This is followed by the transfer and subsequent separation of the biguanides by the analytical phase containing a high concentration of hydrophobic pairing ion. It is found that such on-line sample pre-treatment can yield comparable analytical characteristics to off-line solid phase extraction procedures if the precolumn is conditioned between sample injections. The columns can be used for large numbers of saliva assays but when plasma is the biological matrix components of the plasma cause rapid deterioration of the precolumn.

ISSN:1082-6076    

DOI:10.1080/10826079608006320

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

High performance liquid chromatography procedures have been developed for the assay of morphine-ondansetron and meperidine-ondansetron mixtures in 0.9% sodium chloride injection. The separation and quantitation of morphine-ondansetron were performed on an underviatized silica column at ambient temperature using a mobile phase of 60:40 v/v 0.01Mmonobasic potassium phosphate pH 4.0 - methanol at a flow rate of 1.0 mL/min with the detection set at 233 nm. The separation was achieved within 20 min. Morphine and ondansetron were linear in the 134–536 and 68–271 μg/mL ranges, respectivly. Accuracy and precision were in the range 0.04–4 and 0.2–1%, respectively, for the two analytes and the limits of detection for morphine and ondansetron were 210 and 110 ng/mL, respectively, based on a signal to noise ratio of 3 and a 20 μL injection. The separation and quantitation of the meperidine-ondansetron mixture were also achieved on an underivatized silica column at ambient temperature using a mobile phase of 60:40 v/v 0.01Mmonobasic potassium phosphate pH 4.0 - methanol at a flow rate of 1.0 mL/min with detection of the two analytes at 254 nm. The separation was achieved within 20 min. Meperidine and ondansetron were linear in the 556–3331 and 89–536 μg/mL ranges, respectively. Accuracy and precision were in the range 0.7–5.1 and 0.1–0.6%, respectively, for the two analytes and the limits of detection for meperidine and ondansetron were 1.73 μg/mL and 47 ng/mL, respectively, based on a signal to noise ratio of 3 and a 20 μL injection.

ISSN:1082-6076    

DOI:10.1080/10826079608006321

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor