摘要:

Influence of the temperature of a drift tube and flow rate of nitrogen as nebulizing gas with 100% hexane and 40% hexane plus 60% (5% H2O in 2-propanol) as mobile phases on the respones of ELS detector for selected standards of ethoxylated alcohols was examined. For optimal conditions (1.5 dm3N2/min, 50°C) calibration curves for both mobile phases were created. The response of ELSD for standards not undergoing evaporation is mainly affected by the composition of the mobile phase.

ISSN:1082-6076    

DOI:10.1080/10826079608006299

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Three chelating ion-exchangers having iminodiacetic acid functional groups immobilised at the surface of different substrates (silica gel, hydrophilic and hydrophobic polymer matrices) were compared for the separation of various alkaline-earth and transition metal ions. The retention of metal ions on two commercially available Diasorb IDA silica (250 mm x 4 mm id.) and Tosoh TSK Gel Chelate 5 PW (75 x 7 mm id.) columns and column packed with poly(styrene-divinylbenzene) substrate coated with Phthalein Purple dye was investigated in maleate, tartrate and oxalate mobile phases. Metal-ion retention increased with pH and with a decrease in eluent concentration. The complexing ability of ion-exchangers decreased in the order IDA-silica > TSK Gel Chelate 5 PW > polystyrene-divinylbenzene coated with Phthalein Purple dye. The selectivity of separation was similar for IDA-silica and TSK Gel Chelate 5 PW and was slightly different for the dye coated column. The chromatographic separation of metal ions is demonstrated in oxalate and tartrate mobile phases.

ISSN:1082-6076    

DOI:10.1080/10826079608006300

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

This study describes a highly sensitive, solid-phase extraction-HPLC/MS/MS assay for cyclophosphamide in human plasma, with a minimum quantifiable level of 0.025 μg mL−1. Plasma samples (0.5 mL) were mixed with 0.01 M ammonium acetate buffer (1.5 mL, pH 4.9) and internal standard (D4 deuterated compound, 50 μL, 5 μg mL−1), and then extracted using Isolute CH(EC) cartridges (100 mg). Contaminants were washed from the cartridges with 0.01 M ammonium acetate:methanol (90:10, 1 mL), prior to the elution of the compounds of interest with 0.1 M ammonium acetate:methanol (50:50, 300 μL). An aliquot (200 μL) of the eluent was injected onto the chromatography system, which consisted of a LiChroCART 4-4 RP-select B, 5 μm cartridge precolumn, protecting a LiChrospher 60 RP-select B, 5 μm (250 x 4 mm id) cartridge analytical column.

ISSN:1082-6076    

DOI:10.1080/10826079608006301

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

A highly sensitive method for the simultaneous direct detection as well as the ratio of intracellular and extracellular nitrite (NO2−) and nitrate (NO3−) in human macrophage (M), plasma and urine has been developed. Samples were deproteinized with the organic solvent acetonirile, lyophilized and reconstituted in buffer, determination and quantification of nitric oxide (NO) stable end products NO2−and NO3−was performed utilizing an isocratic high performance liquid chromatography (HPLC) with an anion exchange column. A mobile phase of 20 mM NaCl with 1mM mono sodium phosphate-NaH2PO4at pH = 7.0 was used. Analyte anions were detected by direct UV-wavelength at 210 nm. Sensitivity in intracellular and extracellular fluids were 0.01 μmol/L for both anions with recovery rates of 99.6–99.4% for NO2−and NO3−. This method has successfully been applied to the determination of nitrite and nitrate in plasma and urine of normal human volunteers as well as in cell line U-937 macrophage cytosol/supernatant. The mean concentration of NO3−in normal plasma (n=22) was 3.1 ± 0.4 μmol/L and NO3−10.3 ± 0.3 μmol/L with ratio of NO2−:NO3−= 0.3; in normal urine (n=22) NO2−was 380 ± 61 μmol/L and NO3−1345 ± 270 μmol/L with ratio of NO2−:NO3−= 0.3; in intracellular human macrophage fluid (n=21) NO2−was 0.66 ± 0.08 mol/L/106M, and NO3−0.68 ± 0.09 mol/L/106M with ratio NO2−:NO3= 1; and in extracellular human macrophage fluid (n=21) NO2−was 0.03 ± 0.01 mol/L/106M and NO3−3.03 ± 0.33 mol/L/106M with ratio NO2−:NO3−= 0.01.

ISSN:1082-6076    

DOI:10.1080/10826079608006302

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

A β-cyclodextrin bonded stationary phase is used for the liquid chromatographic separation of cephalosporins. A complete separation of nine cephalosporins with methanol and tetraethylammonium acetate (TEAA) buffer solution has been demonstrated. It is also found that a 100% of TEAA buffer solution is suitable for the separation of cephalosporins containing a hydrophilic α-amino moiety.

ISSN:1082-6076    

DOI:10.1080/10826079608006303

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

A liquid chromatographic (HPLC) method has been developed to detect chloramphenicol (CAP) in fatty liver. After addition of water, samples were defatted with hexane partition and CAP was extracted by ethyl acetate. A solid-phase extraction protocol was used to recover CAP from the fatty liver extract. CAP was analyzed using a mobile phase of acetonitrile-0.005 M phosphate buffer, pH 7.9 (19:81), an ultraviolet detection wavelength of 278 nm and confirmation by scanning. The column used was a Nova-Pak C18(150 x 3.9 mm). The limit of detection was < 1 ng/g in fatty liver and the mean recovery of CAP was found to be 71% over the concentration range 5–20 ng/g. The analyte identity can be confirmed by the use of scanning detection and by LC/MS method for concentrations less than 10 ng/g.

ISSN:1082-6076    

DOI:10.1080/10826079608006304

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

A simple and reproducible method for the simultaneous determination of the antimicrobial agent pefloxacin and the anti-inflammatory drug fenbufen with its metabolite felbinac in human plasma is described. It involves a two steps liquid-liquid extraction and separation using an Adsorbosphere SAX column with ultraviolet detection at 280 nm. 2-[4-(2′-furoyl)phenyl]propionic acid is used as internal standard. The coefficients of variation are less than 5%. The lower limits of detection are 0.1, 0.3 and 0.1 μg/mL for pefloxacin, fenbufen and felbinac, respectively. This method was found to be applicable to pharmacokinetic and pharmacodynamic studies of each drug after the concomitant administration of pefloxacin and fenbufen.

ISSN:1082-6076    

DOI:10.1080/10826079608006305

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

A sensitive and selective high performance liquid chromatographic assay using UV-detection was developed for the analysis of 403U76, a structurally novel serotonin reuptake inhibitor, and two demethylated metabolites, 515U88 and 336U76 in rat plasma. The compounds were isolated from plasma by liquid extraction followed by back extraction into 0.1N HCl. Extracts were chromatographed on an Apex I phenyl HPLC column cartridge (4.6 mm x 12.5 cm) using a mobile phase of 74% buffer (0.005M PIC-B5 low UV adjusted to pH 2.5 with 85% phosphoric acid) and 26% acetonitrile. The compounds of interest were detected at 210 nm with a lower limit of detection of 5 ng/mL. Overall precision of the assay for 403U76, 515U88, and 336U76, expressed as percent deviation of measured values from true values and percent coefficient of variation, respectively, were ⩽ 9.7 % at plasma concentrations between 5 and 500 ng/mL. This assay has been successfully used to analyze plasma samples from preclinical pharmacokinetic and disposition studies in rats.

ISSN:1082-6076    

DOI:10.1080/10826079608006306

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

A simple high performance liquid chromatographic method was developed to study the pharmacokinetics of dihydro-5,6-dehydrokawain (DDK) in the rat plasma. After addition of an internal standard (osthole), plasma was deproteinized by acetonitrile for sample clean-up. The drugs were separated on a reverse phase column and detected by UV detection at a wavelength 281 nm.

ISSN:1082-6076    

DOI:10.1080/10826079608006307

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

The separation of different types of surfactants of all four groups - anionics, nonionics, cationics and amphoterics, has been achieved by single development on silica plates. Ethanol and a mixture of ethanol with water have been used as the developer instead of various mixtures of much more toxic solvents (chloroform, benzene etc.). A new mode of detection with water has been applied among known agents of detection such as UV light (254 nm and 366 nm) and iodine. Anionic surfactants have shown characteristic white spots with gas bubbles after development with ethanol and detection with water. As auxiliary methods in classification of surfactants by charge type colour reactions, obtained by indicator dyes such as methylene blue, KJ3, and bromphenol blue, have been used as simple detection tests. The reliability of the recommended TLC method has been tested on 28 different surfactants, for which the RFvalues, forms and colours of spots, and gas bubbles have been determined.

ISSN:1082-6076    

DOI:10.1080/10826079608006308

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor