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  • Column liquid chromatography  (6)
  • Springer  (6)
  • American Physical Society
  • Wiley
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Verlag/Herausgeber
  • Springer  (6)
  • American Physical Society
  • Wiley
Erscheinungszeitraum
  • 1
    Digitale Medien
    Digitale Medien
    An improved method for the determination of free sphingosine in serum (1994)
    Springer
    Chromatographia 39 (1994), S. 85-90 
    Details
    ISSN: 1612-1112
    Schlagwort(e): Column liquid chromatography ; Solid phase extraction ; Carbopack B ; Free sphingosine in human plasma
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary A rapid, sensitive and selective high-performance liquid chromatographic method has been developed for the determination of sphingosine in human serum. After precipitation with methanol, the samples were extracted using Carbopack B disposable columns; the sphingosine was eluted with 0.05 M hydrochloric acid in methanol-dichloromethane (20∶80, v/v) and the extract evaporated to dryness at 40°C. The sample residue was then reconstituted with methanol and reacted with o-phthaldialdehyde reagent to produce a fluorescent compound. Separation was performed using an LC-18 column with 0.05 M phosphate buffer (pH 7)-methanol-acetonitrile (15∶80∶5, v/v) as mobile phase. Fluorescence detection was performed with excitation and emission wavelengths of 340 and 455 nm, respectively. The serum extract was re-analyzed with a cyano LC column to minimize the possibility of false positive results. The possible interference of compounds having a structure similar to that of sphingosine was evaluated. The mean recovery of sphingosine was 〉94.5%. The limit of detection of the assay was 1 ng mL−1. The between-run and within-run coefficients of variation for replicate analyses were 〈4.0% and 〈3.4%, respectively. The levels of free sphingosine in the serum of 40 normal subjects (20 male and 20 female) was investigated; the average level was 81.6±41.1 ng mL−1 (mean ±S.D.) for males and 85.5±33.7 ng mL−1 for females.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02320464
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  • 2
    Digitale Medien
    Digitale Medien
    Rapid method for determination of phenylurea herbicides in milk (1994)
    Springer
    Chromatographia 38 (1994), S. 88-92 
    Details
    ISSN: 1612-1112
    Schlagwort(e): Column liquid chromatography ; Phenylurea herbicides ; Milk
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary A method has been developed for the determination of thirteen phenylurea herbicide residues in milk. It involves one-step solvent extraction of the milk with methanol by ultrasonication. The extract is cleaned up on an Amberchrom resin cartridge. Reversed-phase, gradient elution, high-performance liquid chromatography with UV detection at 242 nm is used to analyse the residues. The recovery of thirteen phenylurea pesticides is quantitative, ranging from 71.4% to 97.9% for the individual herbicides investigated at concentrations around 0.05 mg kg−1 and from 65.1% to 95.6% around 0.005 mg kg−1. The method is not associated with any of the emulsion problems common to conventional solvent extraction, which considerably reduce the sample clean-up process compared with existing methods.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02275732
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  • 3
    Digitale Medien
    Digitale Medien
    Comparative study of the use of high-performance liquid chromatography and capillary electrophoresis for determination of phenolic compounds in water samples (1996)
    Springer
    Chromatographia 43 (1996), S. 619-624 
    Details
    ISSN: 1612-1112
    Schlagwort(e): Column liquid chromatography ; Capillary electrophoresis ; Phenolic compounds ; Water samples
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary A comparative study of high-performance liquid chromatography (HPLC) and capillary zone electrophoresis (CZE) for determination of eleven EPA priority phenols in water samples is discussed. The repeatability, linearity and detection limits of both methods are compared. A solid-phase extraction method using a highly cross-linked styrene-divinylbenzene copolymer sorbent is used for the off-line preconcentration process in order to determine these compounds in water at low levels. Both methods are used to determine phenolic compounds in Ebro river and industrial waste water. Identification was achieved by comparison of the UV spectra corresponding to the different peaks, acquired with a diode-array detector, with those in a spectral library.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02292977
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  • 4
    Digitale Medien
    Digitale Medien
    Chromatographic determination of caffeine in pharmaceutical formulations using micellar mobile phases (1996)
    Springer
    Chromatographia 43 (1996), S. 149-152 
    Details
    ISSN: 1612-1112
    Schlagwort(e): Column liquid chromatography ; Caffeine ; Pharmaceutical formulations ; Micellar liquid chromatography
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary An HPLC procedure is described for the determination of caffeine in pharmaceutical preparations. A Spherisorb octadecylsilane ODS-2 C18 analytical column and spectrophotometric detection at 273 nm were used. The chromatographic behaviour of caffeine with different micellar eluents containing sodium dodecyl sulphate (SDS) is described. The determination of caffeine in pharmaceutical preparations was performed by use of a mobile phase containing 0.05 M sodium dodecylsulphate (SDS) and 1.5% propanol at pH7. At a 6.0 μg mL−1 concentration level the peak area and peak height repeatability were 2.6 and 2.4%, respectively. The application of the proposed method to the analysis of five pharmaceutical formulations, using peak heights as the dependent variable, gave recoveries between 85 and 104% of the values declared by the manufacturers. The proposed procedure for the determination of caffeine is rapid (15 min per sample), reliable and free from interferences.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02292943
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  • 5
    Digitale Medien
    Digitale Medien
    Chromatographic determination of lactulose (1987)
    Springer
    Chromatographia 23 (1987), S. 132-136 
    Details
    ISSN: 1612-1112
    Schlagwort(e): Gas chromatography ; Column liquid chromatography ; Thin-layer chromatography ; Analysis of lactulose in carbohydrate mixtures
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary Lactulose is a disaccharide with important implications in medicine, nutrition and dairy technology. It has to be determined usually as a minor component in complex matrices containing many other sugars. This paper describes the different chromatographic techniques (planar, liquid and gas chromatography) which have been proposed for the separation and quantification of lactulose in mixtures with other carbohydrates; the advantages of each technique are compared and some features where more research is necessary are outlined.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02312889
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  • 6
    Digitale Medien
    Digitale Medien
    HPLC determination of pesticides in green bean samples after SPE clean-up (1996)
    Springer
    Chromatographia 43 (1996), S. 265-270 
    Details
    ISSN: 1612-1112
    Schlagwort(e): Column liquid chromatography ; Diode array detection ; Solid-phase extraction (SPE) ; Pesticide analysis ; Multiresidue methods ; Green bean samples
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary A reversed-phase high performance liquid chromatographic (HPLC) method with an acetonitrile-methanol-water mobile phase gradient and photodiode-array detection (DAD) is described for simultaneous determination of 21 pesticides, frequently used in agriculture, of different types, namely organophosphorus, organochlorine,N-methylcarbamates, triazines and phenylureas in vegetable samples. The pesticides were extracted with acetone and then partitioned from the vegetable sample with dichloromethane. Sample clean-up was accomplished by solid-phase extraction (SPE) using both C18 and florisil SPE columns. Average recoveries from green beans ranged from 70.0 to 110.1%. Detection limits of less than 0.1 mg kg−1 were obtained.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02270992
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