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  • 1995-1999  (144)
  • 1990-1994  (178)
  • 1900-1904
  • Column liquid chromatography  (322)
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 29 (1990), S. 419-428 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Acceptor-Donor complexes ; Selectivity enhancement ; Physical properties/retention correlation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The paper describes the retention changes observed when an organic acceptor is added to the mobile phase of a liquid chromatography system. The capacity factor decrease depends on the donor character of the solute. Correlations with ionization potentials, HOMO energies and half wave oxidation potentials demonstrate the role of the organic acceptor. According monstrate the role of the organic acceptor. According to the chromatographic properties of the acceptor which is either unretained (TCNE) or slightly retained (TNF) different retention mechanisms are proposed.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Doxycycline in serum ; Pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Several methods have been described for the analysis of doxycycline in serum which require at least 0.5 mL sample. The assay presented here requires small amounts of serum (0.1 mL) and shows good sensitivity. A Ultrabase C-18 column and mobile phase consisting of acetonitrile-bidistilled water (28∶72) were used, flow rate 1 mL min−1 and monitored at 350 nm. Linearity proved satisfactory between 0.025 and 2.5 μg mL−1 of serum. This assay for doxycycline showed good precision (coefficient of variation 〈6%) and allowed quantitation of serum levels as low as 25 ng mL−1 using 100 μL samples.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Flurazolidone and other nitro-pharmaceuticals ; Quantitative analysis ; Stability tests
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A simple, rapid and precise stability-indicating high performance liquid chromatographic assay for the determination of furazolidone (I), nitrofurazone (II), nitrofurantoin (III), niridazole (IV) and nifuroxime (V) in pure form and in pharmaceutical preparations has been devloped. Reversed phase chromatography was conducted using a Lichrosorb R.P. 18 column (250×4 mm), with methanol-water-buffer pH3 (40∶55∶5) eluent and detection at 365, 375, 367, 368 and 340 nm respectively. Calibration graphs were linear over the concentration ranges 3–18, 1–10, 1–10, 3–18 and 3–18 μm·ml−1. Reoveries from bulk drugs were 99.94–100.00 with a relative standard deviation of 1.02–1.61. Sunlight degradation of most of the studied drugs to 5-nitrofuraldehyde was observed. Accelerated stability studies have been carried out on each drug by exposure to sunlight for different time periods. Graphs of log of the remaining concentration (Log. C) against time indicated that photodecomposition of the nitrocompounds is a first order reaction. The proposed method was applied to some representative dosage forms and the results obtained were in good agreement with those obtained by the official methods.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Urine clean-up ; Arsenic speciation ; Microwave assisted oxidation ; Atomic absorption spectrometry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary An effective clean-up method based on the precipitation of most high molecular mass inorganic salts and organic compounds in ethanol at −15°C has been developed for the determination of arsenite, arsenate, monomethylarsonate (MMA), dimethylarsinate (DMA), arsenobetaine (AsB) and arsenocholine (AsC) in urine. Analyte recovery was close to 100%. The six species were separated on an anionic HPLC column and determined by microwave-assisted oxidation-hydride generation-atomic absorption spectrometry. The detection limits and relative standard deviation of the whole procedure were within the 8–15 μg L−1 and 2.5–5.3% ranges, respectively, which allows application to the analysis of urine of people exposed to arsenic.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Arsenic compounds ; Polymeric styrene divinylbenzene phase ; Ion-pairing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The resolving power of an ion-pair reversed-phase liquid chromatography method, on a polymeric stationary phase (PRP-1) with an alkaline aqueous mobile phase (pH=9) containing tetrabutylammonium cation as ion-pairing agent, is compared with a traditional ion-pairing system using an octadecyl-modified silica column and a neutral aqueous mobile phase (pH=7.3). This chromatographic system (PRP-1 column) provides a rapid means for the determination of two of the most important arsenic species, arsenobetaine and arsenite. Addition of methanol (5%) to the aqueous mobile phase allows the differentation of arsenobetaine from the system peak when using UV detection.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Flow injection analysis ; Combined flow injection/HPLC ; Carbamate pesticides
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary An integrated flow injection (FI)/HPLC system for the total and individual determination of carbamate pesticides (propoxur, carbofuran and carbaryl) is proposed. The determination is based on the alkaline hydrolysis of the analytes and subsequent coupling with diazotized sulphanilic acid to yield the monitored dyes with or without a prior separation step by HPLC in a C18 column. The calibration curves obtained are linear in the μg/ml range and r.s.d. values are between 0.5 and 3.7% in all instances. Injection of the sample into the FI manifold allows the total pesticide content in the sample to be screened. The manifold thus acts as a post-column reactor/detector of the chromatograph for samples with high overall carbamate content, which are also injected into the HPLC instrument. The performance was checked with contaminated water samples.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Flow injection analysis ; Combined methods ; Transition metal ions ; Aqueous samples
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary An automatic method based on the combination of a flow injection (FI) manifold with a liquid chromatograph has been developed for the enrichment and determination of transition metal ions in water samples. Alternatively, the FI configuration can be used as a screening system for the determination of the total concentration of heavy metals. Two-parameter expressions for calibration graphs involving preconcentration time and concentration of the analytes were established for both the FIA and the integrated FIA/HPLC methods. The preconcentration time depends on the concentration level of the analytes in the samples. The method is linear in the range 2–200 ng/ml, with r.s.d. values between 1.5 and 5.0. It has been applied to the determination of copper, lead, zinc, nickel, cobalt, cadmium and manganese in synthetic water samples.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Pre-column derivatisation ; Morpholine and degradation products ; Boiler feed water
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Morpholine and its amine-type thermal degradation products present in boiler feed water and steam condensate were derivatised with N-succinimidyl-p-nitrophenylacetate. These pre-column derivatives were determined by high-performance liquid chromatography with UV detection at 280 nm. The analytical column was Supelco-sil-ODS with an isocratic mobile phase. Morpholine and its breakdown products were monitored in the range 0.01–10 μg ml−1 with a relative standard deviation of 0.4–3.0%. Chromatographic analysis of boiler feed water and steam condensate samples collected from a boiler servicing a petroleum refinery is described.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Micellar liquid phases ; Octanol-water partition coefficient ; Benzene and naphthalene derivatives
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary It is shown that the logarithm of the capacity factor (log k′) for fifteen benzene and naphthalene derivatives in micellar liquid chromatography with forty nine different mobile phases generally correlates better with the logarithm of the octanol-water partition coefficient (log Pow) than the capacity factor (k′). Optimum conditions are established to obtain the best linear correlations of log k′-log Pow.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Aminopropyl-silica sorbent ; Continuous cleanup/preconcentration ; Hydroxyvitamin D3 metabolites ; Flow injection analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A new procedure for continuous cleanup and concentration of hydroxyvitamin D3 metabolites prior to their separation by HPLC and UV-detection is reported. The process is based on the use of aminopropyl-silica as solid-phase sorbent as an alternative to the use of nonpolar sorbents. The improvement thus achieved has been tested by comparing the results with those obtained using octadecyl-C18 as non-polar sorbent. The comparison has been based on the calibration graphs (linear range, detection and quantitation limits), precision and multiple standard addition method.
    Type of Medium: Electronic Resource
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